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High surface density, rapidly star-forming galaxies are observed to have $\approx 50-100\,{\rm km\,s^{-1}}$ line-of-sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale…

Astrophysics of Galaxies · Physics 2016-02-17 Sharanya Sur , Evan Scannapieco , Eve C. Ostriker

The stellar velocity ellipsoid of the solar neighbour is re-examined using intermediate-old mono-abundances stellar groups with high quality chemistry data together with parallaxes and proper motions from Gaia DR1. We find the average…

Astrophysics of Galaxies · Physics 2017-12-20 Borja Anguiano , Steven R. Majewski , Kenneth C. Freeman , Arik W. Mitschang , Martin C. Smith

In earlier papers in this series we determined the intrinsic stellar disc kinematics of fifteen intermediate to late type edge-on spiral galaxies using a dynamical modeling technique. From the photometry we find that intrinsically more…

Astrophysics · Physics 2009-11-10 M. Kregel , P. C. van der Kruit , K. C. Freeman

We use the Herschel Hi-GAL survey data to study the spatial distribution in Galactic longitude and latitude of the interstellar medium and of dense, star-forming clumps in the inner Galaxy. The peak position and width of the latitude…

We present the age-velocity dispersion relation (AVR) in three dimensions in the solar neighbourhood using 3,564 commonly observed sub-giant/red-giant branch stars selected from LAMOST, which gives the age and radial velocity, and…

Astrophysics of Galaxies · Physics 2018-01-31 Jincheng Yu , Chao Liu

High resolution spectra data of red clump stars towards the NGP have been obtained with the high resolution spectrograph Elodie at OHP for Tycho-2 selected stars. Combined with Hipparcos local analogues, we determine both the gravitational…

Astrophysics · Physics 2009-11-07 A. Siebert , O. Bienayme , C. Soubiran

We present the vertical kinematics of stars in the Milky Way's stellar disk inferred from SDSS/SEGUE G-dwarf data, deriving the vertical velocity dispersion, \sigma_z, as a function of vertical height |z| and Galactocentric radius R for a…

Astrophysics of Galaxies · Physics 2012-08-03 Jo Bovy , Hans-Walter Rix , David W. Hogg , Timothy C. Beers , Young Sun Lee , Lan Zhang

In most studies of dust in galaxies, dust is only detected from its emission to approximately the optical radius of the galaxy. By combining the signal of 110 spiral galaxies observed as part of the Herschel Reference Survey, we are able to…

We attempt to recover the mean vertical velocity and vertical velocity dispersion as a function of the Galactic height for a sample drawn from a realistic Galaxy distribution function by following the method presented in Moni Bidin et al.…

Astrophysics of Galaxies · Physics 2014-06-16 Jason Sanders

As heating processes can broaden the distributions of radial actions and the vertical distributions of the Galactic disks, we investigate the vertical distribution of the Galactic disks as a function of radial action based on Apache Point…

Astrophysics of Galaxies · Physics 2023-01-18 Yunpeng Jia , Yuqin Chen , Cuihua Du , Gang zhao

In a disc galaxy the distribution of azimuthal components of velocity is very skew. In the past this skewness has been modelled by superposed Gaussians. We use dynamical arguments to derive an analytic formula that can be fitted to observed…

Astrophysics of Galaxies · Physics 2015-05-30 Ralph Schoenrich , James Binney

We give independent proof of the deficit of stars in the in-plane central disc with respect to the predictions of a pure exponential density distribution. We use three different methods: 1) the inversion of the red clump giant distribution…

Astrophysics · Physics 2009-11-10 M. Lopez-Corredoira , A. Cabrera-Lavers , O. Gerhard , F. Garzon

Having to have low thermal energy, the molecular gas in galaxies is expected to settle in a thin disc near the midplane. However, contradicting this understanding, recent studies have revealed considerably thick molecular discs in nearby…

Astrophysics of Galaxies · Physics 2020-04-29 Narendra Nath Patra

In decomposing the HI rotation curves of disc galaxies, it is necessary to break a degeneracy between the gravitational fields of the disc and the dark halo by estimating the disc surface density. This is done by combining measurements of…

Astrophysics of Galaxies · Physics 2016-01-13 S. Aniyan , K. C. Freeman , O. E. Gerhard , M. Arnaboldi , C. Flynn

We present evidence for a Galactic North-South asymmetry in the number density and bulk velocity of solar neighborhood stars. The number density profile, which is derived from main-sequence stars in the Sloan Digital Sky Survey, shows a…

Astrophysics of Galaxies · Physics 2015-06-04 Lawrence M. Widrow , Susan Gardner , Brian Yanny , Scott Dodelson , Hsin-Yu Chen

Non-axisymmetric components, such as spirals and central bars, play a major role in shaping galactic discs. An important aspect of the disc secular evolution driven by these perturbers is the radial migration of stars. It has been suggested…

Astrophysics of Galaxies · Physics 2015-06-05 I. Minchev , B. Famaey , A. C. Quillen , W. Dehnen , M. Martig , A. Siebert

We study the distribution of orbital eccentricities of stars in thick disks generated by the heating of a pre-existing thin stellar disk through a minor merger (mass ratio 1:10), using N-body/SPH numerical simulations of interactions that…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 P. Di Matteo , M. D. Lehnert , Y. Qu , W. van Driel

We present a study of the vertical structure of the gaseous and stellar disks in a sample of edge-on galaxies (NGC 4157, 4565, and 5907) using BIMA/CARMA 12CO (J = 1 --> 0), VLA H I, and Spitzer 3.6 micron data. In order to take into…

Astrophysics of Galaxies · Physics 2015-06-22 Kijeong Yim , Tony Wong , Rui Xue , Richard J. Rand , Erik Rosolowsky , J. M. van der Hulst , Robert Benjamin , Eric J. Murphy

We present full modeling of tangent point emission of HI as seen in the 21 cm transition in the inner Galaxy ($R \simeq 3-8 \kpc$). The model used takes into account emission from a large path length along the line of sight, corresponding…

Astrophysics · Physics 2011-03-28 Sangeeta Malhotra

We present a study of the evolution of the galaxy Velocity Dispersion Function (VDF) from z=0 to z=1.5 using photometric data from the UKIDSS Ultra Deep Survey (UDS) and Newfirm Medium Band Survey (NMBS) COSMOS surveys. The VDF has been…