20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

The oblateness of the dark matter halos of nearby galaxies and its correlation with gas mass fractions

24 Mar 2023, 09:55
Haus H, Telegrafenberg

Haus H, Telegrafenberg

Potsdam, Germany
Contributed talk SESSION 5 : Near-field cosmology and galaxy masses beyond the Local Group SESSION 5 : Near-field cosmology and galaxy masses beyond the Local Group


Mousumi Das (Indian Institute of Astrophysics)


We present a method to measure the the oblateness parameter q of the dark matter halo of gas rich galaxies that have extended HI disks. We have applied our model to a sample of 20 nearby galaxies that are gas rich and close to face-on, of which 6 are large disk galaxies, 8 have moderate stellar masses and 6 are low surface brightness dwarf galaxies. We have used the stacked HI velocity dispersion and HI surface densities to derive q in the outer disk regions. Our most important result is that gas dominated galaxies (such as LSB dwarfs) that have M(gas)/M(baryons)>0.5 have oblate halos (q < 0.55), whereas stellar dominated galaxies have a range of q values from 0.2 to 1.3. We also find a significant positive correlation between q and stellar mass, which indicates that galaxies with massive stellar disks have a higher probability of having halos that are spherical or slightly prolate, whereas low mass galaxies preferably have oblate halos.

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Primary author

Mousumi Das (Indian Institute of Astrophysics)


Roger ianjamasimanana (Instituto de Astrof ́ısica de Andaluc ́ıa (CSIC)) Prof. Stacy McGaugh (Case Western Reserve University) Prof. James Schombert (University of Oregon) Prof. KS Dwarakanath (Raman Research Institute)

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