Recent observations by Mistele et al. show that the circular velocity curves of isolated galaxies remain flat out to the largest radii probed so far, i.e., ≈1 Mpc. The velocity decline beyond the expected virial radius is not observed. These results imply that the galaxy halo is in thermal equilibrium even at large radii where particles did not have time to relax. The galaxies must have already formed in the isothermal state. How is this possible? In the present note we try to understand the formation of galaxies with warm dark matter in the expanding universe.
References
[1]
Mistele, T., McGaugh, S., Lelli, F., Schombert, J. and Li, P. (2024) Radial Acceleration Relation of Galaxies with Joint Kinematic and Weak-Lensing Data. Journal of Cosmology and Astroparticle Physics, 2024, Article 20. https://doi.org/10.1088/1475-7516/2024/04/020
[2]
Shajib, A.J., Treu, T., Birrer, S. and Sonnenfeld, A. (2021) Dark Matter Haloes of Massive Elliptical Galaxies at z∼0.2 Are Well Described by the Navarro–Frenk–White Profile. Monthly Notices of the Royal Astronomical Society, 503, 2380-2405. https://doi.org/10.1093/mnras/stab536
[3]
Hoeneisen, B. (2023) Understanding the Formation of Galaxies with Warm Dark Matter. Journal of Modern Physics, 14, 1741-1754. https://doi.org/10.4236/jmp.2023.1413103
[4]
Hoeneisen, B. (2024) Understanding Elliptical Galaxies with Warm Dark Matter. Physics of the Dark Universe, 46, Article 101643. https://doi.org/10.1016/j.dark.2024.101643
[5]
Hoeneisen, B. (2019) The Adiabatic Invariant of Dark Matter in Spiral Galaxies. International Journal of Astronomy and Astrophysics, 9, 355-367.
[6]
Hoeneisen, B. (2022) Measurement of the Dark Matter Velocity Dispersion with Dwarf Galaxy Rotation Curves. International Journal of Astronomy and Astrophysics, 12, 363-381. https://doi.org/10.4236/ijaa.2022.124021
[7]
Hoeneisen, B. (2024) Measurements of the Dark Matter Mass, Temperature and Spin. International Journal of Astronomy and Astrophysics, 14, 184-202. https://doi.org/10.4236/ijaa.2024.143012
[8]
Press, W.H. and Schechter, P. (1974) Formation of Galaxies and Clusters of Galaxies by Self-Similar Gravitational Condensation. The Astrophysical Journal, 187, 425-438. https://doi.org/10.1086/152650
[9]
Hoeneisen, B. (2024) Are James Webb Space Telescope Observations Consistent with Warm Dark Matter? International Journal of Astronomy and Astrophysics, 14, 45-60. https://doi.org/10.4236/ijaa.2024.141003
[10]
Hoeneisen, B. (2022) Measurement of the Dark Matter Velocity Dispersion with Galaxy Stellar Masses, UV Luminosities, and Reionization. International Journal of Astronomy and Astrophysics, 12, 258-272. https://doi.org/10.4236/ijaa.2022.123015
[11]
Sheth, R.K. and Tormen, G. (1999) Large-scale Bias and the Peak Background Split. Monthly Notices of the Royal Astronomical Society, 308, 119-126. https://doi.org/10.1046/j.1365-8711.1999.02692.x
[12]
Sheth, R.K., Mo, H.J. and Tormen, G. (2001) Ellipsoidal Collapse and an Improved Model for the Number and Spatial Distribution of Dark Matter Haloes. Monthly Notices of the Royal Astronomical Society, 323, 1-12. https://doi.org/10.1046/j.1365-8711.2001.04006.x
