Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamical masses of early-type galaxies at z~2: Are they truly
  superdense?   We measured stellar velocity dispersions sigma and dynamical masses of 9
massive (M~10^11 Msun) early-type galaxies (ETG) from the GMASS sample at
redshift 1.4<z<2.0. The sigma are based on individual spectra for two galaxies
at z~1.4 and on a stacked spectrum for 7 galaxies with 1.6<z<2.0, with 202-h of
exposure at the ESO Very Large Telescope. We constructed detailed axisymmetric
dynamical models for the objects, based on the Jeans equations, taking the
observed surface brightness (from deep HST/ACS observations), PSF and slit
effects into account. Our dynamical masses M_Jeans agree within ~30% with
virial estimates M_vir=5*Re*sigma^2/G, although the latter tend to be smaller.
This suggests that sizes are not underestimated by more than a similar
fraction. Our M_Jeans also agrees within a factor <2 with the M_pop previously
derived using stellar population models and 11 bands photometry. This confirms
that the galaxies are intrinsically massive. The inferred mass-to-light ratios
M/L_U in the very age-sensitive rest frame U-band are consistent with passive
evolution in the past ~1 Gyr (formation redshift z_f~3). A 'bottom-light'
stellar Initial Mass Function (IMF) appears to be required to ensure close
agreement between M_Jeans and M_pop at z~2, as it does at z~0. The GMASS ETGs
are on average more dense than their local counterpart. However a few percent
of local ETGs of similar dynamical masses also have comparable sigma and mass
surface density Sigma_50 inside Re.

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The categories of this paper are: chem-ph
18
The categories of this paper are: econ
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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
1
The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg