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SUMMARY:Dynamical evolution of the sub-galactic dark matter halos and the 
 effect of the cusp-to-core transformation
DTSTART;VALUE=DATE-TIME:20230322T093300Z
DTEND;VALUE=DATE-TIME:20230322T093500Z
DTSTAMP;VALUE=DATE-TIME:20241114T092433Z
UID:indico-contribution-266@meetings.aip.de
DESCRIPTION:Speakers: Yuka Kaneda (University of Tsukuba)\nIn the hierarch
 ical clustering scenario based on the $\\Lambda$ cold dark matter ($\\Lamb
 da$CDM) model\, sub-galactic dark matter halos (subhalos) are of crucial i
 mportance in building up the larger structures via merging processes. More
 over\, dwarf galaxies around the Milky Way (MW) are ideal sites for studyi
 ng the nature of dark matter since they are dark-matter-dominated systems.
  \n\nWe investigate the mass evolution histories and the evolutional track
 s on the $r_\\mathrm{max}$-$V_\\mathrm{max}$ plane of the subhalos associa
 ted with MW-sized host halos based on the ultra-high resolution cosmologic
 al $N$-body simulation\, Phi-4096 by Ishiyama et al. (2021)\, where $V_\\m
 athrm{max}$ and $r_\\mathrm{max}$ denote the maximum circular velocity and
  the radii where the circular velocity becomes $V_\\mathrm{max}$\, respect
 ively. We report that the evolutional tracks of dwarf-galaxy-mass halos sh
 ow an interesting feature compared to the ones of massive halos shown in t
 he literature. The mass evolution of subhalos clearly shows two phases: th
 e accretion phase and the stripping phase. First\, more than 90% of our sa
 mple subhalos increase their masses gradually until the redshift $z=1-2$ (
 accretion phase)\, and then the masses decrease due to the tidal stripping
  driven by the host halo (stripping phase). Thus\, we show quantitatively 
 that tidal stripping plays an essential role in the dynamical evolution of
  subhalos.\n\nIn addition\, the mass density profile of subhalos has a lon
 g-standing disagreement between the observations and the predictions by th
 e pure CDM simulations\, known as the cusp-core problem. Standing on a hyp
 othesis that DM halos are formed primarily with central cusps and then som
 e dynamical processes lead them to form cores\, we provide a ‘core-to-cu
 sp transformation model’ that reverts the properties of cored profile to
  ones of the cusp profile. In constructing a model\, some appropriate cond
 itions are imposed about how the transition should occur\, and detailed ph
 ysical processes are not considered here. The reverted observational prope
 rties\, including $r_\\mathrm{max}$ and $V_\\mathrm{max}$\, show excellent
  agreement with the theoretical prediction from the cosmological $N$-body 
 simulation. This result supports the description that the CDM creates init
 ial cusps in the centre of DM halos\, and some dynamical process gives ris
 e to the cusp-to-core transformation.\n\nhttps://iaus379.aip.de/event/20/c
 ontributions/266/
LOCATION:Haus H\, Telegrafenberg
URL:https://iaus379.aip.de/event/20/contributions/266/
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