相关论文: Are the Ultra-Faint Dwarf Galaxies Just Cusps?

We report on the discovery of a significant and compact over-density of old and metal-poor stars in the KiDS survey (data release 4). The discovery is confirmed by deeper HSC-SSC data revealing the old Main Sequence Turn-Off of a stellar…

Recent kinematical constraints on the internal densities of the Milky Way's dwarf satellites have revealed a discrepancy with the subhalo populations of simulated Galaxy-scale halos in the standard CDM model of hierarchical structure…

We consider the extraction of parameters of dark matter halos hosting ultra-faint dwarf galaxies, in the case where there are only ${\cal O}(10)$ identified member stars with measured line-of-sight velocities. This scenario is likely to be…

Sloan Digital Sky Survey (SDSS) DR5 photometric data with $120^{\circ} < \alpha < 270^{\circ}$, $25^{\circ} < \delta < 70^{\circ}$ are searched for new Milky Way companions or substructures in the Galactic halo. Five candidates are…

Observational investigations of the abundance of massive precursors of local galaxy clusters ("proto-clusters") allow us to test the growth of density perturbations, to constrain cosmological parameters that control it, to test the theory…

For the first time, systematic studies of dwarf galaxies are being conducted throughout the Local Volume, including the dwarf satellites of the nearby giant elliptical galaxy Centaurus A (NGC 5128). Given Centaurus As mass (roughly ten…

We introduce the notion of a Bayesian analysis motivated `reliability' that gives a truer distinction of cusp-core and other halo-parameters (like mass-concentration) in an ensemble of observed galaxies. Our approach goes beyond the…

We show that measuring the proper motion of ${{\sim 2000}}$ stars within a dwarf galaxy, with an uncertainty of 1 km/s at most, can establish whether the Dark Matter (DM) density profile of the dwarf has a central core or cusp. We derive…

The vertical profiles of chain and spiral galaxies in the Hubble Space Telescope Ultra Deep Field (UDF) are fit to sech^2(z/z_0) functions convolved with stellar profiles in order to measure the disk scale heights z_0 in four passbands. The…

Dwarf galaxies are small, dark matter-dominated galaxies, some of which are embedded within the Milky Way. Their lack of baryonic matter (e.g., stars and gas) makes them perfect test beds for probing the properties of dark matter --…

The properties of dwarf galaxies orbiting the Milky Way (MW) are useful for testing models of the formation of our Galaxy, and by extension various theories of cosmology. Recent efforts to measure the masses of the MW's satellite dwarf…

Neutral hydrogen observations with the Westerbork Synthesis Radio Telescope are presented for a sample of 73 late-type dwarf galaxies. These observations are part of the WHISP project (Westerbork HI Survey of Spiral and Irregular Galaxies).…

In this paper the counts and colors of the faint galaxies observed in the Hubble Deep Field are fitted by means of simple luminosity evolution models which incorporate a numerous population of fading dwarfs. The observed color distribution…

We present the first spectroscopic analysis of the faint and compact stellar system Draco II (Dra II, M_V=-2.9+/-0.8, r_h=19^{+8}_{-6} pc), recently discovered in the Pan-STARRS1 3{\pi} survey. The observations, conducted with DEIMOS on the…

We use $\Lambda$CDM cosmological hydrodynamical simulations to explore the kinematics of gaseous discs in late-type dwarf galaxies. We create high-resolution 21-cm 'observations' of simulated dwarfs produced in two variations of the EAGLE…

We use numerical simulations to examine the substructure within galactic and cluster mass halos that form within a hierarchical universe. Clusters are easily reproduced with a steep mass spectrum of thousands of substructure clumps that…

The "super-puffs" are a population of planets that have masses comparable to that of Neptune but radii similar to Jupiter, leading to extremely low bulk densities ($\rho_p \lesssim 0.2\,\mathrm{g}\,\mathrm{cm}^{-3}$) that are not easily…

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding sdBs with compact companions like supermassive white dwarfs (M>1.0 Msun), neutron stars or black holes. The existence of such…

We test competing models that aim at explaining the nature of stars in the Milky Way that are well away (|z|$\gtrsim$ 1kpc) from the midplane, the so-called thick disk: the stars may have gotten there through orbital migration, through…

The cold dark matter scenario predicts that a large number of dark subhalos should be located within the halo of each Milky-way sized galaxy. One tell-tale signature of such dark subhalos could be additional milliarcsecond-scale image…