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The halo of NGC 891 has been the subject of studies for more than a decade. One of its most striking features is the large asymmetry in H$\alpha$ emission. In this letter, we will take a quantitative look at this asymmetry at different…

Astrophysics · Physics 2009-11-13 P. Kamphuis , B. W. Holwerda , R. J. Allen , R. F. Peletier , P. C. van der Kruit

We perform a series of simulations of a Galactic mass dark matter halo at different resolutions, our largest uses over three billion particles and has a mass resolution of 1000 M_sun. We quantify the structural properties of the inner dark…

We report the alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations. The combination of these state-of-the-art hydro-cosmological simulations enables us to span four orders of…

We use Fabry-Perot Halpha spectroscopy, complemented with published HI radio synthesis observations to derive high resolution rotation curves of spiral galaxies. We investigate precisely their inner mass distribution and compare it to CDM…

Astrophysics · Physics 2007-05-23 Sebastien Blais-Ouellette , Claude Carignan , Philippe Amram

In this paper, we use the outer-galactic HI scale height data as well as the observed rotation curve as constraints to determine the halo density distribution of the Andromeda galaxy (M31). We model the galaxy as a gravitationally-coupled…

Astrophysics · Physics 2009-11-13 Arunima Banerjee , Chanda J. Jog

We present 2-D stellar kinematics of M87 out to R = 238" taken with the integral field spectrograph VIRUS-P. We run a large set of axisymmetric, orbit-based dynamical models and find clear evidence for a massive dark matter halo. While a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Jeremy D. Murphy , Karl Gebhardt , Joshua J. Adams

We develop a flexible set of action-based distribution functions (DFs) for stellar haloes. The DFs have five free parameters, controlling the inner and outer density slope, break radius, flattening and anisotropy respectively. The DFs…

Astrophysics of Galaxies · Physics 2015-09-30 A. A. Williams , N. W. Evans

The distribution of shapes of galaxies' dark halos provides a basic test for models of galaxy formation. To-date, few dark halo shapes have been measured, and the results of different methods appear contradictory. Here, we add to the sample…

Astrophysics · Physics 2007-05-23 R. P. Olling , M. R. Merrifield

We construct a suite of discrete chemo-dynamical models of the giant elliptical galaxy NGC 5846. These models are a powerful tool to constrain both the mass distribution and internal dynamics of multiple tracer populations. We use Jeans…

As part of our current programme to test LCDM predictions for dark matter (DM) haloes using extended kinematical observations of early-type galaxies, we present a dynamical analysis of the bright elliptical galaxy NGC 4374 (M84) based on…

Halo stars orbit within the potential of the Milky Way and hence their kinematics can be used to understand the underlying mass distribution. However, the inferred mass distribution depends sensitively upon assumptions made on the density…

Astrophysics of Galaxies · Physics 2015-06-22 Prajwal R. Kafle , Sanjib Sharma , Geraint F. Lewis , Joss Bland-Hawthorn

A seven-parameter distribution function (DF) is fitted to $20\,000$ RR-Lyrae stars for which only astrometric data are available. The observational data are predicted by the DF in conjunction with the gravitational potential of a…

Astrophysics of Galaxies · Physics 2022-01-05 Chengdong Li , James Binney

We model the dynamical structure of M87 (NGC4486) using high spatial resolution long-slit observations of stellar light in the central regions, two-dimensional stellar light kinematics out to half of the effective radius, and globular…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-24 Karl Gebhardt , Jens Thomas

Much of our understanding of dark matter halos comes from the assumption that the mass-to-light ratio (M/L) of spiral disks is constant. The best way to test this hypothesis is to measure the disk surface mass density directly via the…

Astrophysics of Galaxies · Physics 2014-11-20 Kimberly A. Herrmann , Robin Ciardullo

Previous studies have shown that the kinematics of the field elliptical galaxy NGC 7507 do not necessarily require dark matter. This is troubling because, in the context of LCDM cosmologies, all galaxies should have a large dark matter…

Astrophysics of Galaxies · Physics 2015-06-23 Richard R. Lane , Ricardo Salinas , Tom Richtler

The dark matter (DM) halos of field elliptical galaxies have not been well studied and their properties appear controversial. While some galaxies appear to be nearly devoid of DM, others show clear evidence of its presence. Furthermore,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 R. Salinas , T. Richtler , L. P. Bassino , A. J. Romanowsky , Y. Schuberth

NGC 4494 is one of several intermediate-luminosity elliptical galaxies inferred to have an unusually diffuse dark matter halo. We use the chi^2-made-to-measure particle code NMAGIC to construct axisymmetric models of NGC 4494 from…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Lucia Morganti , Ortwin Gerhard , Lodovico Coccato , Inma Martinez-Valpuesta , Magda Arnaboldi

The Elliptical Isolated X-ray (ElIXr) Galaxy Survey is a volume-limited (<110Mpc) study of optically selected, isolated, Lstar elliptical galaxies, to provide an X-ray census of galaxy-scale (virial mass, Mvir < 1e13 Msun) objects, and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Philip J. Humphrey , David A. Buote , Ewan O'Sullivan , Trevor J. Ponman

We present new observations of the gravitational lens (GL) system B1600+434, strongly suggesting that the lens is an edge-on spiral galaxy. These observations are used to constrain the mass model of the system, in particular the oblateness…

Astrophysics · Physics 2009-10-30 L. V. E. Koopmans , A. G. de Bruyn , N. Jackson

We study the distribution of dark matter in the Draco dwarf spheroidal galaxy by modelling the moments of the line-of-sight velocity distribution of stars obtained from new velocity data of Wilkinson et al. The luminosity distribution is…

Astrophysics · Physics 2009-11-10 Ewa L. Lokas , Gary A. Mamon , Francisco Prada