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تسجيل مستخدم جديدThe DEEP2 Galaxy Redshift Survey: Probing the Evolution of Dark Matter Halos around Isolated Galaxies at z ~ 1
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تأليف
Charlie Conroy
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Using the first 25% of DEEP2 Redshift Survey data, we probe the line-of-sight velocity dispersion profile for isolated galaxies with absolute B-band magnitude -22<M_B-5log(h)<-21 at z=0.7-1.0, using satellite galaxies as luminous tracers of the underlying velocity distribution. Measuring the velocity dispersion beyond a galactocentric radius of ~200 kpc/h (physical) permits us to determine the total mass, including dark matter, around these bright galaxies. We find a line-of-sight velocity dispersion (sigma_los) of 162^{+44}_{-30} km/s at ~110 kpc/h, 136^{+26}_{-20} km/s at ~230 kpc/h, and 150^{+55}_{-38} km/s at ~320 kpc/h. Assuming an NFW model for the dark matter density profile, this corresponds to a mass within r_{200} of M_200=5.5^{+2.5}_{-2.0} x 10^12 M_Sun/h for our sample of satellite hosts with mean luminosity ~2.5L*. Roughly $~60% of these host galaxies have early-type spectra and are red in restframe (U-B) color, consistent with the overall DEEP2 sample in the same luminosity and redshift range. The halo mass determined for DEEP2 host galaxies is consistent with that measured in the Sloan Digital Sky Survey for host galaxies within a similar luminosity range relative to M*_B. This comparison is insensitive to the assumed halo mass profile, and implies an increase in the dynamical mass-to-light ratio (M_200/L_B) of isolated galaxies which host satellites by a factor of ~2.5 from z ~ 1 to z ~ 0. Our results are consistent with scenarios in which galaxies populate dark matter halos similarly from z ~ 0 to z ~ 1, except for ~1 magnitude of evolution in the luminosity of all galaxies.
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