Hostname: page-component-7dd5485656-pnlb5 Total loading time: 0.001 Render date: 2025-10-31T06:33:15.015Z Has data issue: false hasContentIssue false
  • English
  • Français

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

Published online by Cambridge University Press:  30 October 2025

Mousumi Das Open the ORCID record for Mousumi Das [Opens in a new window] ,
Roger Ianjamasimanana ,
Stacy McGaugh ,
James Schombert  and
K. S. Dwarakanath
Mousumi Das*
Affiliation:
Indian Institute of Astrophysics, Bengaluru 560034, India
Roger Ianjamasimanana
Affiliation:
Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, E-18008 Granada, Spain
Stacy McGaugh
Affiliation:
Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
James Schombert
Affiliation:
Department of Physics, University of Oregon, 120 Willamette Hall, 1371 E 13th Avenue, Eugene, OR 97403461, USA
K. S. Dwarakanath
Affiliation:
Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bengaluru, Karnataka 560080, India
*
email: mousumi@iiap.res.in
Get access Rights & Permissions [Opens in a new window]

Abstract

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 (LSB) 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<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. We briefly also discuss how the halo shape affects the disks of galaxies, especially the oblate halos.

Keywords

Galaxies: spiralsGalaxies : dwarfsDark Matter halosHI line emissionGalaxy Structure

Information

Type
Contributed Paper
Information
Proceedings of the International Astronomical Union , Volume 19 , Symposium S379: Dynamical Masses of Local Group Galaxies , December 2023 , pp. 353 - 359
Check for updates
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of International Astronomical Union

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

Ansar, S., Kataria, S. K., & Das, M. 2023, MNRAS, 522, 2967.Google Scholar
Banerjee, A. & Jog, C. J. 2008, ApJ, 685, 254.Google Scholar
Banerjee, A. & Jog, C. J. 2011, ApJL, 732, L8.Google Scholar
Chua, K. T. E., Pillepich, A., Vogelsberger, M., et al. 2019, MNRAS, 484, 476.Google Scholar
Combes, F. 2014, Multi-Spin Galaxies, 486, 207.Google Scholar
Das, M., Sengupta, C., & Honey, M. 2019, ApJ, 871, 197.Google Scholar
Das, M., Ianjamasimanana, R., McGaugh, S. S., et al. 2023, ApJL, 946, L8.Google Scholar
Das, M., McGaugh, S. S., Ianjamasimanana, R., et al. 2020, ApJ, 889, 10.Google Scholar
Dubinski, J. 1994, ApJ, 431, 617.Google Scholar
Kent, S. M. 1987, AJ, 93, 816.Google Scholar
Kim, J.-. hoon. & Lee, J. 2013, MNRAS, 432, 1701.Google Scholar
Kreckel, K., Peebles, P. J. E., van Gorkom, J. H., et al. 2011, AJ, 141, 204.Google Scholar
Kregel, M., van der Kruit, P. C., & de Grijs, R. 2002, MNRAS, 334, 646.Google Scholar
Kumar, A., Das, M., & Kataria, S. K. 2022, MNRAS, 509, 1262.Google Scholar
O’Brien, J. C., Freeman, K. C., & van der Kruit, P. C. 2010, Astronomy & Astrophysics, 515, A62.CrossRefGoogle Scholar
Olling, R. P. 1996, AJ, 112, 481.Google Scholar
Pearson, S., Price-Whelan, A. M., Hogg, D. W., et al. 2022, ApJ, 941, 19.Google Scholar
Posti, L. & Helmi, A. 2019, Astronomy & Astrophysics, 621, A56.CrossRefGoogle Scholar
Ianjamasimanana, R., de Blok, W. J. G., & Heald, G. H. 2017, AJ, 153, 213.Google Scholar
Prada, J., Forero-Romero, J. E., Grand, R. J. J., et al. 2019, MNRAS, 490, 4877.Google Scholar
Sellwood, J. A. 2016, ApJ, 819, 92.Google Scholar
Yurin, D. & Springel, V. 2015, MNRAS, 452, 2367.Google Scholar