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Filamentary structure is important for the ISM and star formation. Galactic distribution of filaments may regulate the star formation rate in the Milky Way. However, interstellar filaments are intrinsically complex, making it difficult to…

星系天体物理 · 物理学 2024-06-12 Ke Wang , Yifei Ge , Tapas Baug

We study the formation of the Milky Way's halo in a $\Lambda$CDM cosmology by scaling down a high resolution simulation of the formation of a cluster of galaxies. We determine how much phase-space substructure is left over from the objects…

天体物理学 · 物理学 2009-09-25 Amina Helmi , Simon D. M. White , Volker Springel

We use archival UV absorption-line data from HST/STIS to statistically analyse the absorption characteristics of the high-velocity clouds (HVCs) in the Galactic halo towards more than 40 extragalactic background sources. We determine…

宇宙学与河外天体物理 · 物理学 2015-06-12 Peter Herenz , Philipp Richter , Jane C. Charlton , Joseph R. Masiero

We analyse the dynamical properties of substructures in a high-resolution dark matter simulation of the formation of a Milky Way-like halo in a $\Lambda$CDM cosmology. Our goal is to shed light on the dynamical peculiarities of the Milky…

天体物理学 · 物理学 2008-03-11 Yang-Shyang Li , Amina Helmi

Detailed studies of stellar populations in the halos of the Milky Way and the Andromeda (M 31) galaxies have shown increasing numbers of tidal streams and dwarf galaxies, attesting to a complicated and on-going process of hierarchical…

星系天体物理 · 物理学 2015-07-15 Andreas Koch , Charles W. Danforth , R. Michael Rich , Rodrigo Ibata , Brian A. Keeney

The cross-section of sky occupied by a particular neutral hydrogen column density provides insight into the nature of Lyman-alpha absorption systems. We have measured this column density distribution at z=0 using 21-cm HI emission from a…

天体物理学 · 物理学 2007-05-23 Emma Ryan-Weber , Rachel Webster , Lister Staveley-Smith

The silicate cross section peak near 10um produces emission and absorption features in the spectra of dusty galactic nuclei observed with the Spitzer Space Telescope. Especially in ultraluminous infrared galaxies, the observed absorption…

天体物理学 · 物理学 2010-11-11 N. A. Levenson , M. M. Sirocky , L. Hao , H. W. W. Spoon , J. A. Marshall , M. Elitzur , J. R. Houck

Stellar halos of galaxies retain crucial clues to their mass assembly history. It is in these galactic components that the remains of cannibalised galactic building blocks are deposited. For the case of the Milky Way, the opportunity to…

星系天体物理 · 物理学 2024-04-29 Danny Horta , Ricardo P. Schiavon

The hierarchical mergers that form the haloes of dark matter surrounding galaxies, groups and clusters are not entirely efficient, leaving substantial amounts of dense substructure, in the form of stripped halo cores or `subhaloes',…

天体物理学 · 物理学 2009-11-07 James E. Taylor , Arif Babul

We present the abundance analysis of 97 nearby metal-poor (-3.3<[Fe/H]<-0.5) stars having kinematics characteristics of the Milky Way (MW) thick disk, inner, and outer stellar halos. The high-resolution, high-signal-to-noise optical spectra…

星系天体物理 · 物理学 2015-06-05 M. N. Ishigaki , M. Chiba , W. Aoki

We investigate the properties of HI-rich galaxies detected in blind radio surveys within the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. By drawing a detailed comparison between the properties…

星系天体物理 · 物理学 2015-05-18 Katsuya Okoshi , Masahiro Nagashima , Naoteru Gouda , Yousuke Minowa

There is accumulating evidence that the faint end of the galaxy luminosity function might be very different in different locations. The luminosity function might be rising in rich clusters and flat or declining in regions of low density. If…

天体物理学 · 物理学 2009-11-07 R. Brent Tully , Rachel S. Somerville , Neil Trentham , Marc A. W. Verheijen

The formation of galactic discs and the efficiency of star formation within them are issues central to our understanding of galaxy formation. We have developed a detailed and versatile model of disc formation which combines the strengths of…

天体物理学 · 物理学 2011-11-09 M. J. Stringer , A. J. Benson

Young stellar groupings and clusters have hierarchical patterns ranging from flocculent spiral arms and star complexes on the largest scale to OB associations, OB subgroups, small loose groups, clusters and cluster subclumps on the smallest…

天体物理学 · 物理学 2007-05-23 Bruce G. Elmegreen

The origins of most stellar streams in the Milky Way are unknown. With improved proper motions provided by Gaia EDR3, we show that the orbits of 23 Galactic stellar streams are highly clustered in orbital phase space. Based on their…

High resolution gravity plus smoothed particle hydrodynamics simulations are used to study the formation of galaxies within the context of hierarchical structure formation. The simulations have sufficient dynamic range to resolve from ten…

天体物理学 · 物理学 2007-05-23 F J Summers

We study the formation of galaxies by using $N$-body/hydrodynamics simulations to investigate how baryons collect at the centre of dark matter halos. We treat the dark matter as a collisionless fluid and the baryons as an ideal gas. We…

天体物理学 · 物理学 2015-06-24 Julio F. Navarro , Carlos S. Frenk , Simon D. M. White

Stellar photometry obtained using the Hubble Space Telescope is used to study the distributions of the number densities of stars of various ages in 12 irregular and dwarf spiral galaxies viewed edge-on. Two subsystems can be distinguished…

天体物理学 · 物理学 2007-05-23 N. A. Tikhonov

Various arguments strongly suggest that the population of ultraluminous X-ray sources (ULXs: apparent X-ray luminosity > Eddington limit for 10 Msun ~10^39 erg/s) in nearby galaxies are mostly stellar-mass X-ray binaries in unusual…

天体物理学 · 物理学 2009-11-10 Andrew R. King , Walter Dehnen

Theory and observations agree that the accreted stellar halos (ASHs) of Milky Way-like galaxies display significant scatter. I take advantage of this stochasticity to invert the link between halo assembly history (HAH) and ASH, using mock…

星系天体物理 · 物理学 2017-05-31 Nicola C. Amorisco