THE VELOCITY FUNCTION IN THE LOCAL ENVIRONMENT FROM {lambda}CDM AND {lambda}WDM CONSTRAINED SIMULATIONS
- MPA/SHAO Joint Center for Astrophysical Cosmology at Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China)
- Grupo de Astrofisica, Universidad Autonoma de Madrid, E-28049 (Spain)
- Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)
- Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
- Max-Planck-Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)
Using constrained simulations of the local universe for generic cold dark matter (CDM) and for 1 keV warm dark matter (WDM), we investigate the difference in the abundance of dark matter halos in the local environment. We find that the mass function (MF) within 20 h{sup -1} Mpc of the Local Group is {approx}2 times larger than the universal MF in the 10{sup 9}-10{sup 13} h{sup -1} M {sub sun} mass range. Imposing the field of view of the ongoing H I blind survey Arecibo Legacy Fast ALFA (ALFALFA) in our simulations, we predict that the velocity function (VF) in the Virgo-direction region (VdR) exceeds the universal VF by a factor of 3. Furthermore, employing a scheme to translate the halo VF into a galaxy VF, we compare the simulation results with a sample of galaxies from the early catalog release of ALFALFA. We find that our simulations are able to reproduce the VF in the 80-300 km s{sup -1} velocity range, having a value {approx}10 times larger than the universal VF in the VdR. In the low-velocity regime, 35-80 km s{sup -1}, the WDM simulation reproduces the observed flattening of the VF. In contrast, the simulation with CDM predicts a steep rise in the VF toward lower velocities; for V{sub max} = 35 km s{sup -1}, it forecasts {approx}10 times more sources than the ones observed. If confirmed by the complete ALFALFA survey, our results indicate a potential problem for the CDM paradigm or for the conventional assumptions about energetic feedback in dwarf galaxies.
- OSTI ID:
- 21313744
- Journal Information:
- Astrophysical Journal, Vol. 700, Issue 2; Other Information: DOI: 10.1088/0004-637X/700/2/1779; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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