scholarly journals Resolved HI in two ultra–diffuse galaxies from contrasting non-cluster environments

2021 ◽  
Author(s):  
T C Scott ◽  
Chandreyee Sengupta ◽  
P Lagos ◽  
Aeree Chung ◽  
O Ivy Wong
Keyword(s):  
Dark Matter ◽  
Compact Group ◽  
Optical Spectroscopy ◽  
Radio Telescope ◽  
Spectral Resolution ◽  
Milky Way ◽  
Tidal Interaction

Abstract We report on the first resolved H i observations of two blue ultra-diffuse galaxies (UDGs) using the Giant Metrewave Radio Telescope (GMRT). These observations add to the so-far limited number of UDGs with resolved H i data. The targets are from contrasting non–cluster environments: UDG–B1 is projected in the outskirts of Hickson Compact Group 25 and Secco–dI–2 (SdI–2) is an isolated UDG. These UDGs also have contrasting effective radii with Re of 3.7 kpc (similar to the Milky Way) and 1.3 kpc respectively. SdI–2 has an unusually large $\frac{M_{\rm H\, \rm \small {I}}}{M_*}$ ratio =28.9, confirming a previous single dish H i observation. Both galaxies display H i morphological and kinematic signatures consistent with a recent tidal interaction, which is also supported by observations from other wavelengths, including optical spectroscopy. Within the limits of the observations’ resolution our analysis indicates that SdI–2 is dark matter-dominated within its H i radius and this is also likely to be the case for UDG–B1.Our study highlights the importance of high spatial and spectral resolution H i observations for the study of the dark matter properties of UDGs.

scholarly journals Substructure in Dwarf Galaxies

2004 ◽  
Vol 21 (4) ◽  
pp. 379-381
Author(s):  
Matthew Coleman
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Large Scale ◽  
Stellar Population ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Tidal Interaction ◽  
Kinematic Evolution ◽  
Dark Material ◽  
Star Formation Histories

AbstractRecent years have seen a series of large-scale photometric surveys with the aim of detecting substructure in nearby dwarf galaxies. Some of these objects display a varying distribution of each stellar population, reflecting their star formation histories. Also, dwarf galaxies are dominated by dark matter, therefore luminous substructure may represent a perturbation in the underlying dark material. Substructure can also be the effect of tidal interaction, such as the disruption of the Sagittarius dSph by the Milky Way. Therefore, substructure in dwarf galaxies manifests the stellar, structural, and kinematic evolution of these objects.

scholarly journals Mapping Atomic Hydrogen in the Disk of the Milky Way

2013 ◽  
Vol 23 (2) ◽  
pp. 107
Author(s):  
Nguyen Van Hiep ◽  
Pham Tuan Anh ◽  
Pierre Darriulat ◽  
Pham Ngoc Diep ◽  
Pham Ngoc Dong ◽  
...  
Keyword(s):  
Dark Matter ◽  
Radio Telescope ◽  
Differential Rotation ◽  
Atomic Hydrogen ◽  
Milky Way ◽  
Hydrogen Gas ◽  
Dark Matter Halo

The VATLY radio telescope has been used to draw the map of atomic hydrogen gas in the disk of the Milky Way. Evidence has been obtained for its differential rotation, its cloud and arm structure and the presence of a dark matter halo.

Radio recombination line observations towards Spitzer infrared bubbles with the TianMa radio telescope

2019 ◽  
Vol 489 (4) ◽  
pp. 4862-4874
Author(s):  
L G Hou ◽  
X Y Gao
Keyword(s):  
Radio Telescope ◽  
Detection Rate ◽  
Milky Way ◽  
Absorption Method ◽  
Recombination Line ◽  
Ionized Gas ◽  
Radio Recombination Line ◽  
Warm Ionized Medium

ABSTRACT Many of the Spitzer infrared bubbles identified by the Milky Way Project (MWP) are suggested to be $\rm{H \small {II}} $ regions in nature. More than 70 per cent of the ∼5000 known bubbles do not have radio recombination line (RRL) observations, hence have not been confirmed as $\rm{H \small {II}} $ regions. A systematic RRL survey should be helpful to identify the nature of the bubbles. With the Shanghai TianMa 65-m radio telescope, we searched for RRLs towards 216 selected Spitzer bubbles by simultaneously observing 19 RRLs in the C band (4–8 GHz). RRLs are detected in the directions of 75 of the 216 targets. 31 of the 75 RRL sources are classified as new detections, which are possibly from new $\rm{H \small {II}} $ regions or diffuse warm ionized medium; 36 of them are probably from the outskirts of nearby bright $\rm{H \small {II}} $ regions, rather than bubble-encircled ionized gas; and the detected RRLs towards 8 bubbles are identified from known $\rm{H \small {II}} $ regions. For 58 of the 75 RRL sources, we obtained their distances after resolving the kinematic distance ambiguity by combining the results of the H2CO absorption method, the $\rm{H \small {I}} $ emission/absorption method, and the $\rm{H \small {I}} $ self-absorption method. The low detection rate of new $\rm{H \small {II}} $ regions implies that a number of MWP bubbles in the DR1 catalogue are too faint if they are $\rm{H \small {II}} $ regions.

scholarly journals The impact of inelastic self-interacting dark matter on the dark matter structure of a Milky Way halo

2020 ◽  
Author(s):  
Kun Ting Eddie Chua ◽  
Karia Dibert ◽  
Mark Vogelsberger ◽  
Jesús Zavala
Keyword(s):  
Dark Matter ◽  
High Speed ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Direct Detection ◽  
Major Axis ◽  
Inelastic Collisions ◽  
Axis Ratio ◽  
Lower Velocity ◽  
The Impact

Abstract We study the effects of inelastic dark matter self-interactions on the internal structure of a simulated Milky Way (MW)-size halo. Self-interacting dark matter (SIDM) is an alternative to collisionless cold dark matter (CDM) which offers a unique solution to the problems encountered with CDM on sub-galactic scales. Although previous SIDM simulations have mainly considered elastic collisions, theoretical considerations motivate the existence of multi-state dark matter where transitions from the excited to the ground state are exothermic. In this work, we consider a self-interacting, two-state dark matter model with inelastic collisions, implemented in the Arepo code. We find that energy injection from inelastic self-interactions reduces the central density of the MW halo in a shorter timescale relative to the elastic scale, resulting in a larger core size. Inelastic collisions also isotropize the orbits, resulting in an overall lower velocity anisotropy for the inelastic MW halo. In the inner halo, the inelastic SIDM case (minor-to-major axis ratio s ≡ c/a ≈ 0.65) is more spherical than the CDM (s ≈ 0.4), but less spherical than the elastic SIDM case (s ≈ 0.75). The speed distribution f(v) of dark matter particles at the location of the Sun in the inelastic SIDM model shows a significant departure from the CDM model, with f(v) falling more steeply at high speeds. In addition, the velocity kicks imparted during inelastic collisions produce unbound high-speed particles with velocities up to 500 km s−1 throughout the halo. This implies that inelastic SIDM can potentially leave distinct signatures in direct detection experiments, relative to elastic SIDM and CDM.

scholarly journals CONSTRAINTS ON THE SHAPE OF THE MILKY WAY DARK MATTER HALO FROM JEANS EQUATIONS APPLIED TO SLOAN DIGITAL SKY SURVEY DATA

2012 ◽  
Vol 758 (1) ◽  
pp. L23 ◽  
Author(s):  
Sarah R. Loebman ◽  
Željko Ivezić ◽  
Thomas R. Quinn ◽  
Fabio Governato ◽  
Alyson M. Brooks ◽  
...  
Keyword(s):  
Dark Matter ◽  
Survey Data ◽  
Milky Way ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Sky Survey

scholarly journals Testing dark matter and modifications to gravity using local Milky Way observables

2019 ◽  
Vol 100 (8) ◽  
Author(s):  
Mariangela Lisanti ◽  
Matthew Moschella ◽  
Nadav Joseph Outmezguine ◽  
Oren Slone
Keyword(s):  
Dark Matter ◽  
Milky Way

scholarly journals Probing non-spherical dark halos in the Galactic dwarf satellites

2013 ◽  
Vol 9 (S298) ◽  
pp. 411-411
Author(s):  
Kohei Hayashi ◽  
Masashi Chiba
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Line Of Sight ◽  
Spherical Structure ◽  
Spherical Models ◽  
Galactic Satellites ◽  
Best Fitting

AbstractWe construct axisymmetric mass models for dwarf spheroidal (dSph) galaxies in the Milky Way to obtain realistic limits on the non-spherical structure of their dark halos. This is motivated by the fact that the observed luminous parts of the dSphs are actually non-spherical and cold dark matter models predict non-spherical virialized dark halos on sub-galactic scales. Applying these models to line-of-sight velocity dispersion profiles along three position angles in six Galactic satellites, we find that the best fitting cases for most of the dSphs yield not spherical but oblate and flattened dark halos. We also find that the mass of the dSphs enclosed within inner 300 pc varies depending on their total luminosities, contrary to the conclusion of previous spherical models. This suggests the importance of considering non-spherical shapes of dark halos in dSph mass models.

Dark matter result hints at shadow Milky Way

2013 ◽  
Vol 218 (2912) ◽  
pp. 8-9
Author(s):  
Lisa Grossman
Keyword(s):  
Dark Matter ◽  
Milky Way
Sign in / Sign up

Export Citation Format

Share Document