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We report a kinematic signature associated with the observed asymmetry in the distribution of thick disk/inner halo stars interior to the Solar circle described in Paper I. In that paper we found a statistically significant excess (20% to…

天体物理学 · 物理学 2015-06-24 Jeniffer E. Parker , Roberta M. Humphreys , Timothy C. Beers

We address the issue of accuracy in recovering density profiles from observations of rotation curves of galaxies. We ``observe'' and analyze our models in much the same way as observers do the real galaxies. We find that the tilted ring…

天体物理学 · 物理学 2009-11-10 George Rhee , Octavio Valenzuela , Anatoly Klypin , Jon Holtzman , Bhasker Moorthy

We present results from high-resolution N-Body/SPH simulations of rotationally supported dwarf irregular galaxies moving on bound orbits in the massive dark matter halo of the Milky Way.The dwarf models span a range in disk surface density…

We conducted an analysis of the velocity field of dwarf galaxies in the LITTLE THINGS sample, focusing on deriving 2D velocity maps that encompass both the transverse and radial velocity fields. Within the range of radial distances where…

星系天体物理 · 物理学 2025-01-22 Francesco Sylos Labini , Roberto Capuzzo-Dolcetta , Giordano De Marzo , Matteo Straccamore

We present an empirical method to measure the halo mass function (HMF) of galaxies. We determine the relation between the \hi\ line-width from single-dish observations and the dark matter halo mass ($M_{200}$) inferred from rotation curve…

星系天体物理 · 物理学 2020-01-08 Pengfei Li , Federico Lelli , Stacy McGaugh , Marcel S. Pawlowski , Martin A. Zwaan , James Schombert

We use a sample of 83 high-resolution cosmological zoom-in simulations and a semi-analytic model (SAM) to study the stochasticity of galaxy formation in haloes ranging from dwarf to Milky Way masses. Our simulated galaxies reproduce the…

Bars in disk galaxies slow down as they transfer their angular momentum to their dark matter halo via dynamical friction from near-resonant orbits. This bar-halo dynamical friction can become ineffective once phase mixing erases the…

星系天体物理 · 物理学 2026-03-16 Rumi Kodama , Rimpei Chiba , Tetsuro Asano , Junichi Baba , Michiko Fujii

The Tremaine-Weinberg equations are solved for a pattern speed that is allowed to vary with radius. The solution method transforms an integral equation for the pattern speed to a least squares problem with well established procedures for…

宇宙学与河外天体物理 · 物理学 2015-05-28 Jason C. Speights , David J. Westpfahl

HI spatial power spectra (PS) were determined for a sample of 24 nearby dwarf irregular galaxies selected from the LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes - The HI Nearby Galaxy Survey) sample. The two-dimensional…

宇宙学与河外天体物理 · 物理学 2015-06-05 Hong-Xin Zhang , Deidre A. Hunter , Bruce G. Elmegreen

We have obtained VLA and optical follow-up observations of the low-velocity H I source HIZSS 3 discovered by Henning et al. (2000) and Rivers (2000) in a survey for nearby galaxies hidden by the disk of the Milky Way. Its radio…

天体物理学 · 物理学 2009-11-10 Philip Massey , P. A. Henning , R. C. Kraan-Korteweg

It is well-established that strong bars rotating in dense halos generally slow down as they lose angular momentum to the halo through dynamical friction. Angular momentum exchanges between the bar and halo particles take place at…

天体物理学 · 物理学 2009-11-13 J. A. Sellwood , Victor P. Debattista

Rotation curves are the key observational manifestation of the dark matter distribution around late-type galaxies. In a halo model context, the precision of constraints on halo parameters is a complex function of the properties of the…

星系天体物理 · 物理学 2024-02-27 Tariq Yasin , Harry Desmond , Julien Devriendt , Adrianne Slyz

We present I-band photometry, long-slit optical spectroscopy, and new aperture synthesis HI observations for eight late-type spirals with rotation velocities in the range 243 km/s < V_{rot} < 308 km/s. The sample will be used to study the…

天体物理学 · 物理学 2008-11-26 K. Spekkens , R. Giovanelli

More than 10% of the barred galaxies with a direct measurement of the bar pattern speed host an ultrafast bar. These bars extend beyond the corotation radius and challenge our understanding of the orbital structure of barred galaxies. Most…

Many observed disc galaxies harbour a central bar. In the standard cosmological paradigm, galactic bars should be slowed down by dynamical friction from the dark matter halo. This friction depends on the galaxy's physical properties in a…

HI observations of the nearby blue compact dwarf galaxy IC 10 obtained with the Dominion Radio Astrophysical Observatory synthesis telescope (DRAO), for a total integration of $\sim$1000 hours, are presented. We confirm the NW faint 21 cm…

星系天体物理 · 物理学 2020-01-08 Brenda Namumba , Claude Carignan , Tyler Foster , Nathan Deg

We describe fully self-consistent N-body experiments of barred galaxies with massive halos. A rotating bar is braked through dynamical friction with the halo, which occurs on a short time scale when the central density of the halo is high.…

天体物理学 · 物理学 2007-05-23 Victor P. Debattista , J. A. Sellwood

We present an analysis of the properties of HI holes detected in 20 galaxies that are part of "The HI Nearby Galaxy Survey" (THINGS). We detected more than 1000 holes in total in the sampled galaxies. Where they can be measured, their sizes…

宇宙学与河外天体物理 · 物理学 2015-05-19 I. Bagetakos , E. Brinks , F. Walter , W. J. G. de Blok , A. Usero , A. K. Leroy , J. W. Rich , R. C. Kennicutt

We present a statistical study of the properties of diffuse HI in ten nearby galaxies, comparing the HI detected by the single-dish telescope FAST (FEASTS program) and the interferometer VLA (THINGS program), respectively. The THINGS'…

We model the observed vertical distribution of the neutral hydrogen (HI) in the faint (M_B ~ -13.7 mag) edge-on dwarf irregular galaxy KK250. Our model assumes that the galaxy consists of axi-symmetric, co-planar gas and stellar discs in…

星系天体物理 · 物理学 2014-11-18 Narendra Nath Patra , Arunima Banerjee , Jayaram N. Chengalur , Ayesha Begum