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by Jinyi Yang; Xiaohui Fan; Xue-Bing Wu; Feige Wang; Fuyan Bian; Qian Yang; Ian D. McGreer; Weimin Yi; Linhua Jiang; Richard Green; Minghao Yue; Shu Wang; Zefeng Li; Jiani Ding; Simon Dye; Andy Lawrence
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We present initial results from the first systematic survey of luminous $z\sim 5.5$ quasars. Quasars at $z \sim$ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution and the early super-massive black hole growth. However, it has been very challenging to select quasars at redshifts 5.3 $\le z \le$ 5.7 using conventional color selections, due to their similar optical colors to late-type stars, especially M dwarfs, resulting in a...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.03526
Arxiv.org
by Ningyu Tang; Di Li; Carl Heiles; Nannan Yue; J. R. Dawson; Paul F. Goldsmith; Marko Krčo; N. M. McClure-Griffiths; Shen Wang; Pei Zuo; Jorge L. Pineda; Jun-Jie Wang
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We have obtained OH spectra of four transitions in the $^2\Pi_{3/2}$ ground state, at 1612, 1665, 1667, and 1720 MHz, toward 51 sightlines that were observed in the Herschel project Galactic Observations of Terahertz C+. The observations cover the longitude range of (32$^\circ$, 64$^\circ$) and (189$^\circ$, 207$^\circ$) in the northern Galactic plane. All of the diffuse OH emissions conform to the so-called 'Sum Rule' of the four brightness temperatures, indicating optically thin emission...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.05864
Arxiv.org
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Context: In a series of papers, we study the major merger of two disk galaxies in order to establish whether or not such a merger can produce a disc galaxy. Aims: Our aim here is to describe in detail the technical aspects of our numerical experiments. Methods: We discuss the initial conditions of our major merger, which consist of two protogalaxies on a collision orbit. We show that such merger simulations can produce a non-realistic central mass concentration, and we propose simple,...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.02685
Arxiv.org
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Observations of stars in the the solar vicinity show a clear tendency for old stars to have larger velocity dispersions. This relation is called the age-velocity dispersion relation (AVR) and it is believed to provide insight into the heating history of the Milky Way galaxy. Here, in order to investigate the origin of the AVR, we performed smoothed particle hydrodynamic simulations of the self-gravitating multiphase gas disks in the static disk-halo potentials. Star formation from cold and...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.03668
Arxiv.org
by Els Peeters; Charles W. Bauschlicher,; Louis J. Allamandola; Alexander G. G. M. Tielens; Alessandra Ricca; Mark G. Wolfire
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We present 5-20 micron spectral maps of the reflection nebula NGC2023 obtained with the Infrared Spectrograph SL and SH modes on board the Spitzer Space Telescope which reveal emission from polycyclic aromatic hydrocarbons (PAHs), C60, and H2 superposed on a dust continuum. We show that several PAH emission bands correlate with each other and exhibit distinct spatial distributions revealing a spatial sequence with distance from the illuminating star. We explore the distinct morphology of the...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.06585
Arxiv.org
by Matteo Bonato; Anna Sajina; Gianfranco De Zotti; Jed McKinney; Ivano Baronchelli; Mattia Negrello; Danilo Marchesini; Eric Roebuck; Heath Shipley; Noah Kurinsky; Alexandra Pope; Alberto Noriega-Crespo; Lin Yan; Allison Kirkpatrick
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The James Webb Space Telescope's Medium Resolution Spectrometer (MRS), will offer nearly 2 orders of magnitude improvement in sensitivity and >3X improvement in spectral resolution over our previous space-based mid-IR spectrometer, the Spitzer IRS. In this paper, we make predictions for spectroscopic pointed observations and serendipitous detections with the MRS. Specifically, pointed observations of Herschel sources require only a few minutes on source integration for detections of several...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.07239
Arxiv.org
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A set of Smoothed Particle Hydrodynamics simulations of the influence of photoionising radiation and stellar winds on a series of 10$^{4}$M$_{\odot}$ turbulent molecular clouds with initial virial ratios of 0.7, 1.1, 1.5, 1.9 and 2.3 and initial mean densities of 136, 1135 and 9096\,cm$^{-3}$ are presented. Reductions in star formation efficiency rates are found to be modest, in the range $30\%-50\%$ and to not vary greatly across the parameter space. In no case was star formation entirely...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.03653
Arxiv.org
by Luming Sun; Hongyan Zhou; Tuo Ji; Peng Jiang; Bo Liu; Wenjuan Liu; Xiang Pan; Xiheng Shi; Jianguo Wang; Tinggui Wang; Chenwei Yang; Shaohua Zhang; Lauren P. Miller
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In this paper we present an analysis of absorption line variability in mini-BAL quasar LBQS 1206+1052. The SDSS spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of $\sim$700 km s$^{-1}$ and $\sim$1400 km s$^{-1}$ relative to the quasar rest-frame. The former component shows rare Balmer absorption, which is an indicator of high density absorbing gas, thus the quasar is worth follow-up spectroscopic observations. Our follow-up optical...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.02686
Arxiv.org
by M. Glowacki; J. R. Allison; E. M. Sadler; V. A. Moss; S. J. Curran; A. Musaeva; C. Deng; R. Parry; M. C. Sligo
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HI absorption studies yield information on both AGN feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for HI absorption in a sample of 66 compact radio sources at 0.040 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.07036
Arxiv.org
by Jayant Murthy; M. S. Akshaya; S. Ravichandran; R. C. Henry; James Overduin
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We have used GALEX data of the North and South Galactic poles to separate the Galactic and extragalactic components of the diffuse ultraviolet background. We find, consistent with previous observations, an FUV (1531 \AA) offset of $261 \pm 16$ and $263 \pm 16$ photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ \AA $^{-1}$ in the NGP and the SGP, respectively. The corresponding offsets for the NUV (2361 \AA) are $475 \pm 15$ and $535 \pm 19$ photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ \AA $^{-1}$ in the NGP and the...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.07644
Arxiv.org
by Maximilian Eisenreich; Thorsten Naab; Ena Choi; Jeremiah P. Ostriker; Eric Emsellem
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We present three-dimensional hydrodynamical simulations showing the effect of kinetic and radiative AGN feedback on a model galaxy representing a massive quiescent low-redshift early-type galaxy of $M_* = 8.41\times 10^{10} M_\odot$, harbouring a $M_\mathrm{BH} = 4\times 10^8 M_\odot $ black hole surrounded by a cooling gaseous halo. We show that, for a total baryon fraction of $\sim 20\%$ of the cosmological value, feedback from the AGN can keep the galaxy quiescent for about 4.35 Gyr and with...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.06965
Arxiv.org
by Stefano Zibetti; Anna R. Gallazzi; Y. Ascasibar; S. Charlot; L. Galbany; R. Garcia Benito; C. Kehrig; A. de Lorenzo-Caceres; M. Lyubenova; R. A. Marino; I. Marquez; S. F. Sanchez; G. van de Ven; C. J. Walcher; L. Wisotzki
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Galaxies in the local Universe are known to follow bimodal distributions in the global stellar populations properties. We analyze the distribution of the local average stellar-population ages of 654,053 sub-galactic regions resolved on ~1-kpc scales in a volume-corrected sample of 394 galaxies, drawn from the CALIFA-DR3 integral-field-spectroscopy survey and complemented by SDSS imaging. We find a bimodal local-age distribution, with an old and a young peak primarily due to regions in...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.06570
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Galaxy mass assembly is an end product of structure formation in the $\Lambda$CDM cosmology. As an extension of Lee \& Yi (2013), we investigate the assembly history of stellar components in galaxies as a function of halo environments and stellar mass using semi-analytic approaches. In our fiducial model, halo mass intrinsically determines the formation and assembly of the stellar mass. Overall, the ex situ fraction slowly increases in central galaxies with increasing halo mass but sharply...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.07527
Arxiv.org
by Thiem Hoang; Jungyeon Cho; A. Lazarian
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We study the alignment of irregular dust grains by mechanical torques due to the drift of grains through the ambient gas. We first calculate mechanical torques (MATs) resulting from specular reflection of gas atoms for seven irregular shapes: one shape of mirror symmetry, three highly irregular shapes (HIS), and three weakly irregular shapes (WIS). We find that the grain with mirror symmetry experiences negligible MATs due to its mirror-symmetry geometry. Three highly irregular shapes can...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1704.02256
Arxiv.org
by Bing-Ru Wang; Lei Qian; Di Li; Zhi-Chen Pan
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We estimated the ortho-{\rm{H$_2$O}} abundances of G267.9--1.1, G268.4--0.9, G333.1--0.4 and G336.5--1.5, four of the brightest ortho-{\rm{H$_2$O}} sources in the southern sky observed by the Submillimeter Wave Astronomy Satellite (ortho-{\rm{H$_2$O}} 1$_{10}$ -- 1$_{01}$ line, 556.936~GHz). The typical molecular clumps in our sample have H$_2$ column densities of $10 ^{22}$ to $10 ^{23}${\,}cm$^{-2}$ and ortho-{\rm{H$_2$O}} abundances of 10$^{-10}$. Compared with previous studies, the...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1704.08431
Arxiv.org
by R. Herrera-Camus; A. Bolatto; M. Wolfire; E. Ostriker; B. Draine; A. Leroy; K. Sandstrom; L. Hunt; R. Kennicutt; D. Calzetti; J. D. Smith; K. Croxall; M. Galametz; I. de Looze; D. Dale; A. Crocker; B. Groves
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Dynamic and thermal processes regulate the structure of the multi-phase interstellar medium (ISM), and ultimately establish how galaxies evolve through star formation. Thus, to constrain ISM models and better understand the interplay of these processes, it is of great interest to measure the thermal pressure ($P_{\rm th}$) of the diffuse, neutral gas. By combining [C II] 158 $\mu$m, HI, and CO data from 31 galaxies selected from the Herschel KINGFISH sample, we have measured thermal pressures...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.01438
Arxiv.org
by Gabriele Pezzulli; Filippo Fraternali; James Binney
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Massive and diffuse haloes of hot gas (coronae) are important intermediaries between cosmology and galaxy evolution, storing mass and angular momentum acquired from the cosmic web until eventual accretion on to star-forming discs. We introduce a method to reconstruct the rotation of a galactic corona, based on its angular momentum distribution (AMD). This allows us to investigate in what conditions the angular momentum acquired from tidal torques can be transferred to star forming discs and...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.01442
Arxiv.org
by Kareem El-Badry; Daniel R. Weisz; Eliot Quataert
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We use Monte Carlo simulations to explore the statistical challenges of constraining the characteristic mass ($m_c$) and width ($\sigma$) of a lognormal sub-solar initial mass function (IMF) in Local Group dwarf galaxies using direct star counts. For a typical Milky Way (MW) satellite ($M_{V} = -8$), jointly constraining $m_c$ and $\sigma$ to a precision of $\lesssim 20\%$ requires that observations be complete to $\lesssim 0.2 M_{\odot}$, if the IMF is similar to the MW IMF. A similar...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.02347
Arxiv.org
by Chien-Hsiu Lee
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M31, our closest neighboring galaxy, is a stepping stone to studies of stellar evolution, star formation, galaxy evolution, and cosmology. However, due to the difficulties of performing photometry in such crowded fields and the lack of wide cameras to encompass the entire galaxy, there has not been a complete census of the stellar contents of M31. The advent of wide-field camera provides us a unique opportunity to have a complete view of our neighboring galaxy, enabling an inventory of its...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.02507
Arxiv.org
by Aa. Sandqvist; Å. Hjalmarson; U. Frisk; S. Lundin; L. Nordh; M. Olberg; G. Olofsson
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Context. The Odin satellite is now into its sixteenth year of operation, much surpassing its design life of two years. One of the sources which Odin has observed in great detail is the Sgr A Complex in the centre of the Milky Way. Aims. To study the presence of NH3 in the Galactic Centre and spiral arms. Methods. Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the Sgr A +50 km/s Cloud and Circumnuclear Disk (CND). Results. Significant NH3 emission has been...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.02536
Arxiv.org
by Anna Ferré-Mateu; Ignacio Trujillo; Ignacio Martín-Navarro; Alexandre Vazdekis; Mar Mezcua; Marc Balcells; Lilian Domínguez
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We confirm two new local massive relic galaxies, i.e. untouched survivors of the early universe massive population: Mrk1216 and PGC032873. Both show early and peaked formation events within very short timescales ( 2 massive population, setting them apart of the typical z~0 massive early-type galaxies. We find that there seems to exist a "degree of relic" that is related on how far into the path to become one of these typical z~0 massive galaxies the compact relic has undergone. This...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.05197
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We study the limits of the spatial and velocity resolution of radio interferometry to infer the mass of supermassive black holes (SMBHs) in galactic centres using the kinematics of circum-nuclear molecular gas, by considering the shapes of the galaxy surface brightness profile, signal-to-noise ratios (S/Ns) of the position-velocity diagram (PVD) and systematic errors due to the spatial and velocity structure of the molecular gas. We argue that for fixed galaxy stellar mass and SMBH mass, the...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.05683
Arxiv.org
by Smitha Subramanian; Stefano Rubele; Ning-Chen Sun; Léo Girardi; Richard de Grijs; Jacco Th. van Loon; Maria-Rosa L. Cioni; Andrés E. Piatti; Kenji Bekki; Jim Emerson; Valentin D. Ivanov; Leandro Kerber; Marcella Marconi; Vincenzo Ripepi; Benjamin L. Tatton
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We study the luminosity function of intermediate-age red-clump stars using deep, near-infrared photometric data covering $\sim$ 20 deg$^2$ located throughout the central part of the Small Magellanic Cloud (SMC), comprising the main body and the galaxy's eastern wing, based on observations obtained with the VISTA Survey of the Magellanic Clouds (VMC). We identified regions which show a foreground population ($\sim$11.8 $\pm$ 2.0 kpc in front of the main body) in the form of a distance bimodality...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.05722
Arxiv.org
by Peeter Tenjes; Taavi Tuvikene; Antti Tamm; Rain Kipper; Elmo Tempel
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Aims: Density waves are often considered as the triggering mechanism of star formation in spiral galaxies. Our aim is to study relations between different star formation tracers (stellar UV and near-IR radiation and emission from HI, CO and cold dust) in the spiral arms of M31, to calculate stability conditions in the galaxy disc and to draw conclusions about possible star formation triggering mechanisms. Methods: We select fourteen spiral arm segments from the de-projected data maps and...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.05815
Arxiv.org
by B. W. Meyers; N. Hurley-Walker; P. J. Hancock; T. M. O. Franzen; E. Carretti; L. Staveley-Smith; B. M. Gaensler; M. Haverkorn; S. Poppi
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The S-band Polarisation All-Sky Survey (S-PASS) has observed the entire southern sky using the 64-metre Parkes radio telescope at 2.3GHz with an effective bandwidth of 184MHz. The surveyed sky area covers all declinations $\delta\leq 0^\circ$. To analyse compact sources the survey data have been re-processed to produce a set of 107 Stokes $I$ maps with 10.75arcmin resolution and the large scale emission contribution filtered out. In this paper we use these Stokes $I$ images to create a total...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.08887
Arxiv.org
by Miroslava Dessauges-Zavadsky; Daniel Schaerer; Antonio Cava; Lucio Mayer; Valentina Tamburello
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We analyse stellar masses of clumps drawn from a compilation of star-forming galaxies at 1.1
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.00055
Arxiv.org
by David Neufeld; Paul F. Goldsmith; Claudia Comito; Anika Schmiedeke
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We report the results of a sensitive search for the 443.952902 GHz $J=1-0$ transition of the LiH molecule toward two interstellar clouds in the Milky Way, W49N and Sgr B2 (Main), that has been carried out using the Atacama Pathfinder Experiment (APEX) telescope. The results obtained toward W49N place an upper limit of $1.9 \times 10^{-11}\, (3\sigma)$ on the LiH abundance, $N({\rm LiH})/N({\rm H}_2)$, in a foreground, diffuse molecular cloud along the sight-line to W49N, corresponding to 0.5%...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.03296
Arxiv.org
by Shany Danieli; Pieter van Dokkum; Allison Merritt; Roberto Abraham; Jielai Zhang; I. D. Karachentsev; L. N. Makarova
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We obtained follow-up HST observations of the seven low surface brightness galaxies discovered with the Dragonfly Telephoto Array in the field of the massive spiral galaxy M101. Out of the seven galaxies, only three were resolved into stars and are potentially associated with the M101 group at $D=7\text{ Mpc}$. Based on HST ACS photometry in the broad F606W and F814W filters, we use a maximum likelihood algorithm to locate the Tip of the Red Giant Branch (TRGB) in galaxy color-magnitude...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.04727
Arxiv.org
by S. J. Curran; M. T. Whiting; J. R. Allison; A. Tanna E. M. Sadler; R. Athreya
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We report on a survey for associated HI 21-cm and OH 18-cm absorption with the Giant Metrewave Radio Telescope at redshifts z = 0.2-0.4. Although the low redshift selection ensures that our targets are below the critical ultra-violet luminosity, which is hypothesised to ionise all of the neutral gas in the host galaxy, we do not obtain any detections in the six sources searched. Analysing these in context of the previous surveys, in addition to the anti-correlation with the ultra-violet...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.04788
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We present 2.5-square-degree C$_{2}$H N=1-0 and N$_2$H$^+$ J=1-0 maps of the $\rho$ Ophiuchi molecular cloud complex. These are the first large-scale maps of the $\rho$ Ophiuchi molecular cloud complex with these two tracers. The C$_{2}$H emission is spatially more extended than the N$_2$H$^+$ emission. One faint N$_2$H$^+$ clump Oph-M and one C$_{2}$H ring Oph-RingSW are identified for the first time. The observed C$_{2}$H to N$_{2}$H$^{+}$ abundance ratio ([C$_{2}$H]/[N$_{2}$H$^{+}$]) varies...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.04857
Arxiv.org
by R. Canameras; N. P. H. Nesvadba; R. Kneissl; M. Limousin; R. Gavazzi; D. Scott; H. Dole; B. Frye; S. Koenig; E. Le Floc'h; I. Oteo
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We study the properties of the foreground galaxy of the Ruby, the brightest gravitationally lensed high-redshift galaxy on the sub-millimeter sky as probed by the Planck satellite, and part of our sample of Planck's Dusty GEMS. The Ruby consists of an Einstein ring of 1.4" diameter at z = 3.005 observed with ALMA at 0.1" resolution, centered on a faint, red, massive lensing galaxy seen with HST/WFC3, which itself has an exceptionally high redshift, z = 1.525 $\pm$ 0.001, as confirmed...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.02984
Arxiv.org
by Sarah Pearson; Adrian M. Price-Whelan; Kathryn V. Johnston
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Recent Pan-STARRS data show that the leading arm from the globular cluster Palomar 5 (Pal 5) appears shorter than the trailing arm, while simulations of Pal 5 predict similar angular extents. We demonstrate that including the spinning Galactic bar with appropriate pattern speeds in the dynamical modeling of Pal 5 can reproduce the Pan-STARRS data. As the bar sweeps by, some stream stars experience a difference in net torques near pericenter. This leads to the formation of apparent gaps along...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.04627
Arxiv.org
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We investigate the relation between star formation rate (SFR) and stellar mass ($M_*$) in sub-galactic ($\sim 1$kpc) scale of 93 local ($0.0110^{10.5}M_{\odot}$) spiral galaxies. To derive spatially-resolved SFR and stellar mass, we perform so-called pixel-to-pixel SED fitting, which fits an observed spatially-resolved multiband SED with a library of model SEDs using Bayesian statistics approach. We use 2 bands (FUV and NUV) and 5 bands ($u$, $g$, $r$, $i$, and $z$) imaging data from Galaxy...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1704.04571
Arxiv.org
by Preetish K. Mishra; Yogesh Wadadekar; Sudhanshu Barway
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We examine the dependence of the fraction of galaxies containing pseudo bulges on environment for a flux limited sample of $\sim$5000 SDSS galaxies. We have separated bulges into classical and pseudo bulge categories based on their position on the Kormendy diagram. Pseudo bulges are thought to be formed by internal processes and are a result of secular evolution in galaxies. We attempt to understand the dependence of secular evolution on environment and morphology. Dividing our sample of...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1701.07641
Arxiv.org
by E. V. Polyachenko; P. Berczik; A. Just
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Many barred galaxies, possibly including the Milky Way, have cusps in the centres. There is a widespread belief, however, that usual bar instability taking place in bulgeless galaxy models is impossible for the cuspy models, because of the presence of the inner Lindblad resonance for any pattern speed. At the same time there are numerical evidences that the bar instability can form a bar. We analyse this discrepancy, by accurate and diverse N-body simulations and using the calculation of normal...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.01646
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We present a modification of the method for reconstructing the stellar velocity ellipsoid (SVE) in disc galaxies. Our version does not need any parametrization of the velocity dispersion profiles and uses only one assumption that the ratio $\sigma_z/\sigma_R$ remains constant along the profile or along several pieces of the profile. The method was tested on two galaxies from the sample of other authors and for the first time was applied to three lenticular galaxies NGC~1167, NGC~3245 and...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1702.07687
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by Mario Romero; Yago Ascasibar
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This work introduces a new interpretation of the gravitational N-body problem, based on the one-point probability density {\Psi} of finding a particle at a given loca- tion of phase space (x, v) at time t and the associated expected phase-space $\bar{f}$(x, v, t) = M {\Psi}(x, v, t), where M is the total mass of the system. At variance with the traditional paradigm, we consider that the problem is inherently stochastic, and therefore $\bar{f}$ corresponds to a weighted average over all possible...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.05313
Arxiv.org
by C. R. O'Dell; W. Kollatschny; G. J. Ferland
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The common assumption that Theta-1-Ori C is the dominant ionizing source for the Orion Nebula is critically examined. This assumption underlies much of the existing analysis of the nebula. In this paper we establish through comparison of the relative strengths of emission lines with expectations from Cloudy models and through the direction of the bright edges of proplyds that Theta-2-Ori-A, which lies beyond the Bright Bar, also plays an important role. Theta-1-Ori-C does dominate ionization in...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.06191
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by Dana Simard; Ue-Li Pen
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Recent observations of scintillating pulsars' dynamic and secondary spectra show evidence for collinear compact ionized structures in the interstellar medium. One proposed explanation for these structures is that they are the crests of Alfv\'en waves propagating along current sheets closely aligned to our line-of-sight to the pulsar. Using geometric optics, we develop a simple model of these folded current sheets that makes observable predictions for how the secondary spectrum of the pulsar...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1703.06855
Arxiv.org
by Eugenio Carretta; Angela Bragaglia; Sara Lucatello; Valentina D'Orazi; Raffaele G. Gratton; Paolo Donati; Antonio Sollima; Chris Sneden
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As part of our on-going project on the homogeneous chemical characterization of multiple stellar populations in globular clusters (GCs), we studied NGC 5634, associated to the Sagittarius dwarf spheroidal galaxy, using high-resolution spectroscopy of red giant stars collected with FLAMES@VLT. We present here the radial velocity distribution of the 45 observed stars, 43 of which are member, the detailed chemical abundance of 22 species for the seven stars observed with UVES-FLAMES, and the...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.03116
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by Baitian Tang; Guy Worthey
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Spectral absorption features can be used to constrain the stellar initial mass function (IMF) in the integrated light of galaxies. Spectral indices used at low redshift are in the far red, and therefore increasingly hard to detect at higher and higher redshifts as they pass out of atmospheric transmission and CCD detector wavelength windows. We employ IMF-sensitive indices at bluer wavelengths. We stack spectra of red, quiescent galaxies around $z=0.4$, from the DEEP2 Galaxy Redshift Survey....
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1701.03683
Arxiv.org
by O. V. Melnyk; V. E. Karachentseva; I. D. Karachentsev
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We examine the star formation properties of galaxies with very thin disks selected from the Revised Flat Galaxy Catalog (RFGC). The sample contains 333 ultra-flat galaxies (UFG) at high Galactic latitudes, $|b|>10^{\circ}$, with a blue major angular diameter of $a\geq 1.2^{\prime}$, blue and red apparent axial ratios of $(a/b)_b > 10$, $(a/b)_r > 8.5$ and radial velocities within 10000~km s$^{-1}$. As a control sample for them we use a population of 722 more thick RFGC galaxies with...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1702.00266
Arxiv.org
by Clotilde Laigle; Christophe Pichon; Stephane Arnouts; Henry Joy McCracken; Yohan Dubois; Julien Devriendt; Adrianne Slyz; Damien Le Borgne; Aurelien Benoit-Levy; Ho Seong Hwang; Olivier Ilbert; Katarina Kraljic; Nicola Malavasi; Changbom Park; Didier Vibert
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The variations of galaxy stellar masses and colour-types with the distance to projected cosmic filaments are quantified using the precise photometric redshifts of the COSMOS2015 catalogue extracted from COSMOS field (2 deg$^{2}$). Realistic mock catalogues are also extracted from the lightcone of the cosmological hydrodynamical simulation Horizon-AGN. They show that the photometric redshift accuracy of the observed catalogue ($\sigma_z 10^{10}{\rm M}_{\odot}$ and $z
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1702.08810
Arxiv.org
by Dante Minniti; Tali Palma; Istvan Dékány; Maren Hempel; Marina Rejkuba; Joyce Pullen; Javier Alonso-García; Rodolfo Barbá; Beatriz Barbuy; Eduardo Bica; Charles Bonatto; Jura Borissova; Marcio Catelan; Julio A. Carballo-Bello; Andre Nicolas Chene; Juan J. Clariá; Roger E. Cohen; Rodrigo Contreras-Ramos; Bruno Dias; Jim Emerson; Dirk Froebrich; Anne S. M. Buckner; Douglas Geisler; Oscar A. Gonzalez; Felipe Gran; Gergely Hagdu; Mike Irwin; Valentin D. Ivanov; Radostin Kurtev; Philip W....
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We use deep multi-epoch near-IR images of the VISTA Variables in the V\'ia L\'actea (VVV) Survey to search for RR Lyrae stars towards the Southern Galactic plane. Here we report the discovery of a group of RR Lyrae stars close together in VVV tile d025. Inspection of the VVV images and PSF photometry reveals that most of these stars are likely to belong to a globular cluster, that matches the position of the previously known star cluster FSR\,1716. The stellar density map of the field yields a...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.02033
Arxiv.org
by Judith Ineson; Judith H. Croston; Martin J. Hardcastle; Beatriz Mingo
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We report the first large, systematic study of the dynamics and energetics of a representative sample of FRII radio galaxies with well-characterized group/cluster environments. We used X-ray inverse-Compton and radio synchrotron measurements to determine the internal radio-lobe conditions, and these were compared with external pressures acting on the lobes, determined from measurements of the thermal X-ray emission of the group/cluster. Consistent with previous work, we found that FRII radio...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1701.05612
Arxiv.org
by Anupam Bhardwaj; Lucas M. Macri; Marina Rejkuba; Shashi M. Kanbur; Chow-Choong Ngeow; Harinder P. Singh
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We present time-series observations of Population \rom{2} Cepheids in the Large Magellanic Cloud at near-infrared ($JHK_s$) wavelengths. Our sample consists of 81 variables with accurate periods and optical ($VI$) magnitudes from the OGLE survey, covering various subtypes of pulsators (BL Herculis, W Virginis and RV Tauri). We generate light curve templates using high-quality $I$-band data in the LMC from OGLE and $K_s$-band data in the Galactic Bulge from VVV and use them to obtain robust mean...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.00967
Arxiv.org
by Didier Fraix-Burnet; Paola Marziani; Mauro D 'Onofrio; Deborah Dultzin
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The connection between multifrequency quasar observational and physical parameters related to accretion processes is still open to debate. In the last 20 year, Eigenvector 1-based approaches developed since the early papers by Boroson and Green (1992) and Sulentic et al. (2000b) have been proven to be a remarkably powerful tool to investigate this issue, and have led to the definition of a quasar "main sequence". In this paper we perform a cladistic analysis on two samples of 215 and...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1702.02468
Arxiv.org
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Recent studies suggest that the quenching properties of galaxies are correlated over several mega-parsecs. The large-scale "galactic conformity" phenomenon around central galaxies has been regarded as a potential signature of "galaxy assembly bias" or "pre-heating", both of which interpret conformity as a result of direct environmental effects acting on galaxy formation. Building on the iHOD halo quenching framework developed in Zu & Mandelbaum (2015, 2016), we...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1703.09219
Arxiv.org
by Clio Bertelli Motta; Maurizio Salaris; Anna Pasquali; Eva K. Grebel
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Recent works have shown how the [C/N] ratio in stars after the first dredge-up (FDU) can be used as an age estimator in virtue of its dependence on stellar mass. For this purpose, precise predictions of the surface chemical composition before and after the mixing takes place in the convective envelope of subgiant stars are necessary. Stellar evolution models can provide us with such predictions, although a comparision with objects of known age is needed for calibration. Open clusters are...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.00979
Arxiv.org
by L. R. Patrick; C. J. Evans; B. Davies; R-P. Kudritzki; A. M. N. Ferguson; M. Bergemann; G. Pietrzyński; O. Turner
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We present K-band Multi-Object Spectrograph (KMOS) observations of 18 Red Supergiant (RSG) stars in the Sculptor Group galaxy NGC 55. Radial velocities are calculated and are shown to be in good agreement with previous estimates, confirming the supergiant nature of the targets and providing the first spectroscopically confirmed RSGs in NGC 55. Stellar parameters are estimated for 14 targets using the $J$-band analysis technique, making use of state-of-the-art stellar model atmospheres. The...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.06966
Arxiv.org
by Shuji Matsuura; Toshiaki Arai; James J. Bock; Asantha Cooray; Phillip M. Korngut; Min Gyu Kim; Hyung Mok Lee; Dae Hee Lee; Louis R. Levenson; Toshio Matsumoto; Yosuke Onishi; Mai Shirahata; Kohji Tsumura; Takehiko Wada; Michael Zemcov
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The Extragalactic Background Light (EBL) captures the total integrated emission from stars and galaxies throughout the cosmic history. The amplitude of the near-infrared EBL from space absolute photometry observations has been controversial and depends strongly on the modeling and subtraction of the Zodiacal light foreground. We report the first measurement of the diffuse background spectrum at 0.8-1.7 um from the CIBER experiment. The observations were obtained with an absolute spectrometer...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1704.07166
Arxiv.org
by S. Parsa; J. S. Dunlop; R. J. McLure
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We reinvestigate a claimed sample of 22 X-ray detected active galactic nuclei (AGN) at redshifts z > 4, which has reignited the debate as to whether young galaxies or AGN reionized the Universe. These sources lie within the GOODS-S/CANDELS field, and we examine both the robustness of the claimed X-ray detections (within the Chandra 4Ms imaging) and perform an independent analysis of the photometric redshifts of the optical/infrared counterparts. We confirm the reality of only 15 of the 22...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1704.07750
Arxiv.org
by Juan P. Farias; Jonathan C. Tan; Sourav Chatterjee
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We investigate the formation and early evolution of star clusters assuming that they form from a turbulent starless clump of given mass bounded inside a parent self-gravitating molecular cloud characterized by a particular mass surface density. As a first step we assume instantaneous star cluster formation and gas expulsion. We draw our initial conditions from observed properties of starless clumps. We follow the early evolution of the clusters up to 20 Myr, investigating effects of different...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.00701
Arxiv.org
by Josep M. Masqué; Luis F. Rodríguez; Miguel A. Trinidad; Stan Kurtz; Sergio A. Dzib; Carlos A. Rodríguez-Rico; Laurent Loinard
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Ultra-Compact (UC)HII regions represent a very early stage of massive star formation whose structure and evolution are not yet fully understood. Interferometric observations in recent years show that some UCHII regions have associated compact sources of uncertain nature. Based on this, we carried out VLA 1.3 cm observations in the A configuration of selected UCHII regions in order to report additional cases of compact sources embedded in UCHII regions. From the observations, we find 13 compact...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.02717
Arxiv.org
by George H. Jacoby; Orsola De Marco; James Davies; I. Lotarevich; Howard E. Bond; J. Patrick Harrington; Thierry Lanz
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The globular cluster (GC) system of our Galaxy contains four planetary nebulae (PNe): K 648 (or Ps 1) in M15, IRAS 18333-2357 in M22, JaFu 1 in Pal 6, and JaFu 2 in NGC 6441. Because single-star evolution at the low stellar mass of present-epoch GCs was considered incapable of producing visible PNe, their origin presented a puzzle. We imaged the PN JaFu 1 with the Hubble Space Telescope (HST) to obtain photometry of its central star (CS) and high-resolution morphological information. We imaged...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.03516
Arxiv.org
by Micaela B. Bagley; Claudia Scarlata; Alaina Henry; Marc Rafelski; Matthew Malkan; Harry Teplitz; Y. Sophia Dai; Ivano Baronchelli; James Colbert; Michael Rutkowski; Vihang Mehta; Alan Dressler; Patrick McCarthy; Andrew Bunker; Hakim Atek; Thibault Garel; Crystal L. Martin; Nimish Hathi; Brian Siana
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We present the results of a systematic search for Lyman-alpha emitters (LAEs) at $6 \lesssim z \lesssim 7.6$ using the HST WFC3 Infrared Spectroscopic Parallel (WISP) Survey. Our total volume over this redshift range is $\sim 8 \times10^5$ Mpc$^3$, comparable to many of the narrowband surveys despite their larger area coverage. We find two LAEs at $z=6.38$ and $6.44$ with line luminosities of L$_{\mathrm{Ly}\alpha} \sim 4.7 \times 10^{43}$ erg s$^{-1}$, putting them among the brightest LAEs...
Topics: Astrophysics of Galaxies, Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.05193
Arxiv.org
by J. Etherington; D. Thomas; C. Maraston; I. Sevilla-Noarbe; K. Bechtol; J. Pforr; P. Pellegrini; J. Gschwend; A. Carnero Rosell; M. A. G. Maia; L. N. da Costa; A. Benoit-Lévy; M. E. C. Swanson; W. G. Hartley; T. M. C. Abbott; F. B. Abdalla; S. Allam; R. A. Bernstein; E. Bertin; D. Brooks; E. Buckley-Geer; M. Carrasco Kind; J. Carretero; F. J. Castander; M. Crocce; C. E. Cunha; S. Desai; P. Doel; T. F. Eifler; A. E. Evrard; A. Fausti Neto; D. A. Finley; B. Flaugher; P. Fosalba; J. Frieman; D. W....
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Measurements of the galaxy stellar mass function are crucial to understand the formation of galaxies in the Universe. In a hierarchical clustering paradigm it is plausible that there is a connection between the properties of galaxies and their environments. Evidence for environmental trends has been established in the local Universe. The Dark Energy Survey (DES) provides large photometric datasets that enable further investigation of the assembly of mass. In this study we use ~3.2 million...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1701.06066
Arxiv.org
by Ross A. Burns; Toshihiro Handa; Hiroshi Imai; Takumi Nagayama; Omodaka Toshihiro; Tomoya Hirota; Kazuhito Motogi; Huib van Langevelde; Willem A. Baan
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We present the results of multi-epoch VLBI observations of water masers in the AGFL 5142 massive star forming region. We measure an annual parallax of $\pi=0.467 \pm 0.010$ mas, corresponding to a source distance of $D=2.14^{+0.051}_{-0.049}$ kpc. Proper motion and line of sight velocities reveal the 3D kinematics of masers in this region, most of which associate with millimeter sources from the literature. In particular we find remarkable bipolar bowshocks expanding from the most massive...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.05912
Arxiv.org
by Tiffany Ensor; Jan Cami; Neil H. Bhatt; Andrea Soddu
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We present a principal component analysis of 23 line of sight parameters (including the strengths of 16 diffuse interstellar bands, DIBs) for a well-chosen sample of single-cloud sightlines representing a broad range of environmental conditions. Our analysis indicates that the majority ($\sim$93\%) of the variations in the measurements can be captured by only four parameters The main driver (i.e., the first principal component) is the amount of DIB-producing material in the line of sight, a...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.06180
Arxiv.org
by L. Sabin; M. A. Gómez-Muñoz; M. A. Guerrero; S. Zavala; G. Ramos-Larios; R. Vázquez; L. Corral; M. W. Blanco Cárdenas; P. F. Guillén; L. Olguín; C. Morisset; S. Navarro
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We present the first part of an investigation on the planetary nebula (PN) PC 22 which focuses on the use of deep imaging and high resolution echelle spectroscopy to perform a detailed morpho-kinematical analysis. PC 22 is revealed to be a multipolar PN emitting predominantly in [O III] and displaying multiple non-symmetric outflows. Its central region is found to be also particularly inhomogeneous with a series of low ionization structures (knots) located on the path of the outflows. The...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.00029
Arxiv.org
by F. Yusef-Zadeh; M. Wardle; W. Cotton; R. Schödel; M. J. Royster; D. A. Roberts; D. Kunneriath
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We present radio and mm continuum observations of the Galactic center taken with the VLA and ALMA at 44 and 226 GHz, respectively. We detect radio and mm emission from IRS 3, lying ~4.5" NW of Sgr A*, with a spectrum that is consistent with the photospheric emission from an AGB star at the Galactic center. Millimeter images reveal that the envelope of IRS 3, the brightest and most extended 3.8$\mu$m Galactic center stellar source, consists of two semi-circular dust shells facing the...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.02196
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by M. Daprà; P. Noterdaeme; M. Vonk; M. T. Murphy; W. Ubachs
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Absorption by carbon monoxide in the spectrum of quasar SDSS J000015.16+004833.2 is investigated in order to derive a constraint on the temporal variation of the proton-to-electron mass ratio, mu. The spectrum was recorded using VLT/UVES, and it was partially corrected for long-range wavelength scale distortions using the supercalibration technique. Eight vibrational CO singlet-singlet bands belonging to the A-X electronic absorption system, and the perturbing d3-X(5, 0) singlet-triplet band...
Topics: Astrophysics of Galaxies, Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.03132
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by Chiaki Hikage; Rachel Mandelbaum; Alexie Leauthaud; Eduardo Rozo; Eli S. Rykoff
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Galaxy cluster centering is one of the key issues for precision cosmology studies using galaxy surveys. The red-sequence Matched-filter Probabilistic Percolation (redMaPPer) estimates the centering probability of member galaxies from photometric information; however, the centering algorithm has not previously been well-tested. We test the centering probabilities of redMaPPer cluster catalog using the projected cross correlation between redMaPPer clusters with photometric red galaxies and...
Topics: Astrophysics of Galaxies, Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.08614
Arxiv.org
by D. Massari; A. Mucciarelli; E. Dalessandro; M. Bellazzini; S. Cassisi; G. Fiorentino; R. A. Ibata; C. Lardo; M. Salaris
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We present chemical abundances for 17 elements in a sample of 11 red giant branch stars in NGC 6362 from UVES spectra. NGC 6362 is one of the least massive globulars where multiple populations have been detected, yet its detailed chemical composition has not been investigated so far. NGC 6362 turns out to be a metal-intermediate ([Fe/H]=-1.07\pm0.01 dex) cluster, with its \alpha- and Fe-peak elements content compatible with that observed in clusters with similar metallicity. It also displays an...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.00385
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by John Regan; Eli Visbal; John H. Wise; Zoltan Haiman; Peter H. Johansson; Greg L. Bryan
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The Direct Collapse Black Hole (DCBH) scenario provides a solution for forming the massive black holes powering bright quasars observed in the early Universe. A prerequisite for forming a DCBH is that the formation of (much less massive) Population III stars be avoided - this can be achieved by destroying H$_2$ via Lyman-Werner (LW) radiation (E$_{\rm{LW}}$ = 12.6 eV). We find that two conditions must be met in the proto-galaxy that will host the DCBH. First, prior star formation must be...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1703.03805
Arxiv.org
by Alexandra Pope; Alfredo Montana; Andrew Battisti; Marceau Limousin; Danilo Marchesini; Grant W. Wilson; Stacey Alberts; Itziar Aretxaga; Vladimir Avila-Reese; Jose Ramon Bermejo-Climent; Gabriel Brammer; Hector Bravo-Alfaro; Daniela Calzetti; Ranga-Ram Chary; Ryan Cybulski; Mauro Giavalisco; David Hughes; Erin Kado-Fong; Erica Keller; Allison Kirkpatrick; Ivo Labbe; Daniel Lange-Vagle; James Lowenthal; Eric Murphy; Pascal Oesch; Daniel Rosa Gonzalez; David Sanchez-Arguelles; Heath Shipley;...
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We directly detect dust emission in an optically-detected, multiply-imaged galaxy lensed by the Frontier Fields cluster MACSJ0717.5+3745. We detect two images of the same galaxy at 1.1mm with the AzTEC camera on the Large Millimeter Telescope leaving no ambiguity in the counterpart identification. This galaxy, MACS071_Az9, is at z>4 and the strong lensing model (mu=7.5) allows us to calculate an intrinsic IR luminosity of 9.7e10 Lsun and an obscured star formation rate of 14.6 +/- 4.5...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1703.04535
Arxiv.org
by Luca Graziani; M. de Bennassuti; R. Schneider; D. Kawata; S. Salvadori
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Here we investigate the evolution of a Milky Way (MW) -like galaxy with the aim of predicting the properties of its progenitors all the way from $z \sim 20$ to $z = 0$. We apply GAMESH (Graziani et al. 2015) to a high resolution N-Body simulation following the formation of a MW-type halo and we investigate its properties at $z \sim 0$ and its progenitors in $0 < z < 4$. Our model predicts the observed galaxy main sequence, the mass-metallicity and the fundamental plane of metallicity...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1704.02983
Arxiv.org
by Shigehisa Takakuwa; Kazuya Saigo; Tomoaki Matsumoto; Masao Saito; Jeremy Lim; Tomoyuki Hanawa; Hsi-Wei Yen; Paul T. P. Ho
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We report the ALMA Cycle 2 observations of the Class I binary protostellar system L1551 NE in the 0.9-mm continuum, C18O (3-2), 13CO (3-2), SO (7_8-6_7), and the CS (7-6) emission. At 0.18" (= 25 AU) resolution, ~4-times higher than that of our Cycle 0 observations, the circumbinary disk as seen in the 0.9-mm emission is shown to be comprised of a northern and a southern spiral arm, with the southern arm connecting to the circumstellar disk around Source B. The western parts of the spiral...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.05562
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A large fraction of active galactic nuclei (AGN) are "invisible" in extant optical surveys due to either distance or dust-obscuration. The existence of this large population of dust-obscured, infrared-bright AGN is predicted by models of galaxy - supermassive black hole coevolution and is required to explain the observed X-ray and infrared backgrounds. Recently, infrared colour-cuts with WISE have identified a portion of this missing population. However, as the host galaxy brightness...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1702.06149
Arxiv.org
by David Yong; John E. Norris; Gary S. Da Costa; Laura M. Stanford; Amanda I. Karakas; Luke J. Shingles; Raphael Hirschi; Marco Pignatari
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We present a chemical abundance analysis of a metal-poor star, ROA 276, in the stellar system omega Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X/Fe], for all elements from Cu to Mo along with normal abundance ratios for the elements from Ba to Pb. The chemical abundance pattern of ROA 276, relative to a primordial omega Cen star ROA 46, is best fit by a fast-rotating low-metallicity massive...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.07087
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by Miriam Garcia; Artemio Herrero; Francisco Najarro; Ines Camacho; Daniel J. Lennon; Miguel A. Urbaneja; Norberto Castro
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The double distance and metallicity frontier marked by the SMC has been finally broken with the aid of powerful multi-object spectrographs installed at 8-10m class telescopes. VLT, GTC and Keck have enabled studies of massive stars in dwarf irregular galaxies of the Local Group with poorer metal content than the SMC. The community is working to test the predictions of evolutionary models in the low-metallicity regime, set the new standard for the metal-poor high-redshift Universe, and test the...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.00218
Arxiv.org
by J. C. Beamin; R. A. Mendez; R. L. Smart; R. Jara; R. Kurtev; M. Gromadzki; V. Villanueva; D. Minniti; L. C. Smith; P. W. Lucas
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We use the multi-epoch K$\rm _S$ band observations, covering a $\sim$5 years baseline to obtain milli and sub-milli arcsec precision astrometry for a sample of eighteen previously known high proper motion sources, including precise parallaxes for these sources for the first time. In this study we show the capability of the VVV project to measure high precision trigonometric parallaxes for very low mass stars (VLMS) up to distances of $\sim$250\,pc reaching farther than most other ground based...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.05817
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by Seyma Mercimek; Philip C. Myers; Katherine I. Lee; Sarah I. Sadavoy
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We present the results of our investigation of the star-forming potential in the Perseus star-forming complex. We build on previous starless core, protostellar core, and young stellar object (YSO) catalogs from Spitzer, Herschel, and SCUBA observations in the literature. We place the cores and YSOs within seven star-forming clumps based on column densities greater than 5x10^21 cm^-2. We calculate the mean density and free-fall time for 69 starless cores as 5.55x10^-19 gcm^-3 and 0.1...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1704.07596
Arxiv.org
by K. Kawara; Y. Matsuoka; K. Sano; T. Brandt; H. Sameshima; K. Tsumura; S. Oyabu; N. Ienaka
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We present an analysis of the blank sky spectra observed with the Faint Object Spectrograph on board the Hubble Space Telescope. We study the diffuse sky emission from ultraviolet to optical wavelengths, which is composed of the zodiacal light (ZL), diffuse Galactic light (DGL), and residual emission. The observations were performed toward 54 fields distributed widely over the sky, with the spectral coverage from 0.2 to 0.7 um. In order to avoid contaminating light from the earthshine, we use...
Topics: Earth and Planetary Astrophysics, Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic...
Source: http://arxiv.org/abs/1701.00885
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We present the results of an investigation into the occurrence and properties (stellar age and mass trends) of low-mass field stars exhibiting extreme mid-infrared (MIR) excesses ($L_\mathrm{IR} / L_\ast \gtrsim 0.01$). Stars for the analysis were initially selected from the Motion Verified Red Stars (MoVeRS) catalog of photometric stars with SDSS, 2MASS, and $WISE$ photometry and significant proper motions. We identify 584 stars exhibiting extreme MIR excesses, selected based on an empirical...
Topics: Astrophysics of Galaxies, Solar and Stellar Astrophysics, Astrophysics, Earth and Planetary...
Source: http://arxiv.org/abs/1702.08465
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by Alexander Gallego Cadavid
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We compare the effects of local features (LF) and branch features (BF) of the inflaton potential on the spectrum of primordial perturbations. We show that LF affect the spectrum in a narrow range of scales while BF produce a step between large and small scales with respect to the featureless spectrum. We comment on the possibility of distinguishing between these two types of feature models from the analysis of the Cosmic Microwave Background (CMB) radiation data. We also show that there exists...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.04375
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We reanalyse the cosmic microwave background (CMB) Cold Spot (CS) anomaly with particular focus on understanding the bias a mask (to remove Galactic and point sources contamination) may introduce. We measure the coldest spot, found by applying the Spherical Mexican Hat Wavelet (SMHW) transform on 100,000 masked and unmasked CMB simulated maps. The coldest spot in masked maps is the same as in unmasked maps only 48% of the time, suggesting that false minima are more frequently measured in masked...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.07894
Arxiv.org
by V. I. Abramenko; A. S. Kutsenko; O. I. Tikhonova; V. B. Yurchyshyn
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We studied the emergence process of 42 active region (ARs) by analyzing the time derivative, R(t), of the total unsigned flux. Line-of-sight magnetograms acquired by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) were used. A continuous piecewise linear fitting to the R(t)-profile was applied to detect an interval, dt_2, of nearly-constant R(t) covering one or several local maxima. The averaged over dt_2 magnitude of R(t) was accepted as an estimate of...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.00739
Arxiv.org
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Accurate modelling of solar-like oscillators requires that modelled mode frequencies are corrected for the systematic shift caused by improper modelling of the near-surface layers, known as the surface effect. ... We investigate how much additional uncertainty is introduced to stellar model parameters by our uncertainty about the functional form of the surface effect. At the same time, we test whether any of the parametrizations is significantly better or worse at modelling observed subgiants...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.02570
Arxiv.org
by F. Kahil; T. L. Riethmüller; S. K. Solanki
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We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet Sun (QS) at disc centre, and the brightness at 214 nm, 300 nm, 313 nm, 388 nm, 397 nm, and at 525.02 nm. To this end we analysed spectropolarimetric and imaging time series acquired simultaneously by the IMaX magnetograph and the SuFI filter imager on-board the balloon-borne observatory Sunrise during its first science flight in 2009, with high spatial and temporal resolution....
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.00759
Arxiv.org
by Leigh N. Fletcher; G. S. Orton; J. H. Rogers; A. A. Simon-Miller; I. de Pater; M. H. Wong; O. Mousis; P. G. J. Irwin; M. Jacquesson; P. A. Yanamandra-Fisher
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Mid-infrared 7-20 $\mu$m imaging of Jupiter demonstrates that the increased albedo of Jupiter's South Equatorial Belt (SEB) during the `fade' (whitening) event of 2009-2010 was correlated with changes to atmospheric temperature and aerosol opacity. The opacity of the tropospheric condensation cloud deck at pressures less than 800 mbar increased by 80% between May 2008 and July 2010, making the SEB ($7-17^\circ$ S) as opaque in the thermal infrared as the adjacent equatorial zone. After the...
Topics: Astrophysics, Earth and Planetary Astrophysics
Source: http://arxiv.org/abs/1701.00957
Arxiv.org
by Huan Y. A. Meng; George H. Rieke; Kate Y. L. Su; Andras Gaspar
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We characterize the first 40 Myr of evolution of circumstellar disks through a unified study of the infrared properties of members of young clusters and associations with ages from 2 Myr up to ~ 40 Myr: NGC 1333, NGC 1960, NGC 2232, NGC 2244, NGC 2362, NGC 2547, IC 348, IC 2395, IC 4665, Chamaeleon I, Orion OB1a and OB1b, Taurus, the \b{eta} Pictoris Moving Group, \r{ho} Ophiuchi, and the associations of Argus, Carina, Columba, Scorpius-Centaurus, and Tucana-Horologium. Our work features: 1.) a...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.01786
Arxiv.org
by Roman R. Rafikov
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Protoplanetary disks are believed to evolve on Myr timescales in a diffusive (viscous) manner as a result of angular momentum transport driven by internal stresses. Here we use a sample of 26 protoplanetary disks resolved by ALMA with measured (dust-based) masses and stellar accretion rates to derive the dimensionless $\alpha$-viscosity values for individual objects, with the goal of constraining the angular momentum transport mechanism. We find that the inferred values of $\alpha$ do not...
Topics: Astrophysics, Earth and Planetary Astrophysics
Source: http://arxiv.org/abs/1701.02352
We study the rotation-activity correlations (RACs) in a sample stars from spectral type dK4 to dM4. We study RACs using chromospheric data and coronal data. We study the Ca\,{\sc ii} line surface fluxes-$P/\sin i$ RACs. We fit the RACs with linear homoscedastic and heteroscedastic regression models. We find that these RACs differ substantially from one spectral sub-type to another. For dM3 and dM4 stars, we find that the RACs cannot be described by a simple model, but instead that there may...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.07608
We report the discovery of a post-mass transfer Gamma Doradus/Delta Scuti hybrid pulsator in the eclipsing binary KIC~9592855. This binary has a circular orbit, an orbital period of 1.2 days, and contains two stars of almost identical masses ($M_1=1.72M_{\odot}, M_2=1.71M_{\odot}$). However, the cooler secondary star is more evolved ($R_2=1.96R_{\odot}$) while the hotter primary is still on the zero-age-main-sequence ($R_1=1.53R_{\odot}$). Coeval models from single star evolution cannot explain...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1704.03789
Arxiv.org
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The 21 cm signal from the Epoch of Reionization should be observed within the next decade. While a simple statistical detection is expected with SKA pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract from the observed data constraints on the parameters describing the underlying astrophysical processes, inversion methods must be developed. For example, the Markov Chain Monte Carlo method has been successfully applied. Here we test another possible inversion...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.07026
Arxiv.org
by A. V. Yudin; T. L. Razinkova; D. K. Nadyozhin
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The variational principle for stars with a phase transition has been investigated. The term outside the integral in the expression for the second variation of the total energy of a star is shown to be obtained by passage to the limit from the integration over the region of mixed states in the star. The form of the trial functions ensuring this passage has been found. All of the results have been generalized to the case where general relativity is applicable. The known criteria for the dynamical...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.04546
Arxiv.org
by M. Rossetti; F. Gastaldello; D. Eckert; M. Della Torre; G. Pantiri; P. Cazzoletti; S. Molendi
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We characterized the population of galaxy clusters detected with the SZ effect with Planck, by measuring the cool core state of the objects in a well-defined subsample of the Planck catalogue. We used as indicator the concentration parameter Santos et al. (2008). The fraction of cool core clusters is $29 \pm 4 \%$ and does not show significant indications of evolution in the redshift range covered by our sample. We compare the distribution of the concentration parameter in the Planck sample...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.06961
Arxiv.org
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Both simulations and observations have found that the spin of halo/galaxy is correlated with the large scale environment, and particularly the spin of halo flips in filament. A consistent picture of halo spin evolution in different environments is still lacked. Using N-body simulation we find that halo spin with its environment evolves continuously from sheet to cluster, and the flip of halo spin happens both in filament and nodes. For the flip in filament can be explained by halo formation...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1703.04726
Arxiv.org
by George Voyatzis
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Periodic solutions of the three body problem are very important for understanding its dynamics either in a theoretical framework or in various applications in celestial mechanics. In this paper we discuss the computation and continuation of periodic orbits for planetary systems. The study is restricted to coplanar motion. Staring from known results of two-planet systems around single stars, we perform continuation of solutions with respect to the mass and approach periodic orbits of single...
Topics: Astrophysics, Earth and Planetary Astrophysics
Source: http://arxiv.org/abs/1704.00495
Arxiv.org
by Viggo H. Hansteen; Vasilis Archontis; Tiago M. D. Pereira; Mats Carlsson; Luc Rouppe van der Voort; Jorrit Leenaarts
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A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the H$\alpha$ line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging Spectrograph (IRIS) have revealed another type of plasma "bombs" (UV bursts) with high temperatures of perhaps up to $8\times 10^4$ K within the cooler lower solar atmosphere. Realistic numerical modeling showing such events is needed to explain their nature. Here,...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1704.02872
Arxiv.org
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Rings and gaps are being observed in an increasing number of disks around young stellar objects. We illustrate the formation of such radial structures through idealized, 2D (axisymmetric) resistive MHD simulations of coupled disk-wind systems threaded by a relatively weak poloidal magnetic field (plasma-$\beta \sim 10^3$). We find two distinct modes of accretion depending on the resistivity and field strength. A small resistivity or high field strength promotes the development of rapidly...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.01565
Arxiv.org
by Martin Kilbinger; Catherine Heymans; Marika Asgari; Shahab Joudaki; Peter Schneider; Patrick Simon; Ludovic Van Waerbeke; Joachim Harnois-Déraps; Hendrik Hildebrandt; Fabian Köhlinger; Konrad Kuijken; Massimo Viola
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We compute the spherical-sky weak-lensing power spectrum of the shear and convergence. We discuss various approximations, such as flat-sky, and first- and second- order Limber equations for the projection. We find that the impact of adopting these approximations are negligible when constraining cosmological parameters from current weak lensing surveys. This is demonstrated using data from the Canada-France-Hawaii Lensing Survey (CFHTLenS). We find that the reported tension with Planck Cosmic...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.05301
Arxiv.org
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New forms of empirical formulae that provide an approximate description of the decay of shock pressure with distance in hypervelocity impacts are proposed. These forms, which are intended for use in applications such as large-scale mantle convection models, are continuous and smooth from the point of impact to arbitrarily large distances, thereby avoiding the need to divide the domain into different decay regimes and yielding the maximum pressure in a self-consistent way without resorting to...
Topics: Astrophysics, Earth and Planetary Astrophysics
Source: http://arxiv.org/abs/1702.05537
Arxiv.org
by Clara Froment; Frédéric Auchère; Guillaume Aulanier; Zoran Mikić; Karine Bocchialini; Eric Buchlin; Jacques Solomon
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In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon that can occur when the heating is both highly-stratified and quasi-constant. Unambiguous observational identification of TNE would thus permit to strongly constrain heating scenarios. Up to now, while TNE is the standard interpretation of coronal rain, the long-term periodic evolution predicted by simulations has never been observed yet. However, the detection of long-period intensity pulsations (periods of several hours)...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.01309
Arxiv.org
by Katharine K. Reeves; Michael S. Freed; David E. McKenzie; Sabrina L. Savage
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We perform a detailed analysis of the thermal structure of the region above the post-eruption arcade for a flare that occurred on 2011 October 22. During this event, a sheet of hot plasma is visible above the flare loops in the 131 \AA\ bandpass of the Atmospheric Imaging Assembly (AIA) on the {\it Solar Dynamics Observatory (SDO)}. Supra-arcade downflows (SADs) are observed traveling sunward through the post-eruption plasma sheet. We calculate differential emission measures using the AIA data...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.03497
Arxiv.org
by Eric Lagadec
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This review presents the latest advances in the nebular studies of post-AGB objects. Post-AGB stars are great tools to test nucleosynthesis and evolution models for stars of low and intermediate masses, and the evolution of dust in harsh environment. I will present the newly discovered class of post-RGB stars, formed via binary interaction on the RGB. Binary systems can also lead to the formation of two class of aspherical post-AGB, the Proto-Planetary Nebulae and the naked post-AGBs (dusty RV...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.04324
Arxiv.org
by Gioia Rau; Josef Hron; Claudia Paladini; Benard Aringer; Kjell Eriksson; Paola Marigo; Walter Nowotny; Rebekka Grellmann
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Modeling stellar atmospheres is a complex, intriguing task in modern astronomy. A systematic comparison of models with multi-technique observations is the only efficient way to constrain them. Aims: We performed a self-consistent modeling of the atmospheres of six C-rich AGB stars: R Lep, R Vol, Y Pav, AQ Sgr, U Hya and X TrA, with the aim of enlarging the knowledge of the dynamic processes occurring in their atmospheres. Methods. We used VLTI/MIDI interferometric observations, in combination...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1701.04331
Arxiv.org
by C. L. Fletcher; V. Petit; Y. Naze; G. A. Wade; R. H. Townsend; S. P. Owocki; D. H. Cohen; A. David-Uraz; M. Shultz
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Recent spectropolarimetric surveys of bright, hot stars have found that ~10% of OB-type stars contain strong (mostly dipolar) surface magnetic fields (~kG). The prominent paradigm describing the interaction between the stellar winds and the surface magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the stellar wind plasma is forced to move along the closed field loops of the magnetic field, colliding at the magnetic equator, and creating a shock. As the shocked...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1702.06500
Arxiv.org
by Ethan Dederick; Jason Jackiewicz
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The $\kappa$-mechanism has been successful in explaining the origin of observed oscillations of many types of "classical" pulsating variable stars. Here we examine quantitatively if that same process is prominent enough to excite the potential global oscillations within Jupiter, whose energy flux is powered by gravitational collapse rather than nuclear fusion. Additionally, we examine whether external radiative forcing, i.e. starlight, could be a driver for global oscillations in hot...
Topics: Astrophysics, Earth and Planetary Astrophysics
Source: http://arxiv.org/abs/1702.07988