Kavli Affiliate: Andrey Kravtsov
| First 5 Authors: Andrey Kravtsov, Sophia Winney, , ,
| Summary:
We present a study illustrating the effects of the passage of a Large
Magellanic Cloud (LMC) mass satellite on the distance and velocity
distributions of satellites in $Lambda+$Cold Dark Matter simulations of Milky
Way (MW) sized halos. In agreement with previous studies, we find that during
such a passage the velocity distribution develops a high-velocity tail, which
can bias velocity-based virial halo mass estimates. When the velocity
distribution of MW satellites is corrected for effects of the LMC passage, it
is consistent with the distributions in halos of masses as low as $M_{rm
200c}=8times 10^{11}, M_odot$ and as high as $1.5times 10^{12},M_odot$.
We present a new halo mass estimator $M_{rm 200c}=csigma^2_{rm 3D}r_{rm
med}$, where $c$ is the coefficient calibrated using satellite systems in the
simulated MW-sized halos, $sigma^2_{rm 3D}$ is the variance of 3D velocities
taken with the sign of the radial velocity of each satellite, and $r_{rm med}$
is the median halocentric distance of the satellites. We show that the
estimator has only $s=8%$ scatter around the median relation of the estimated
and true halo masses and deviates by $<2s$ from the median during the
pericentric passage of an LMC-like subhalo. This is because $sigma^2_{rm 3D}$
and $r_{rm med}$ deviate in the opposite directions during such passages. We
apply the estimator to the MW satellite system and estimate the virial mass of
the Milky Way of $M_{rm 200c}=9.96pm 1.45times 10^{11}, M_odot$, in good
agreement with several recent estimates using other methods.
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