The Puzzling Origin of Massive Compact Galaxies in MaNGA. (arXiv:2104.12737v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Schnorr_Muller_A/0/1/0/all/0/1">A. Schnorr-Müller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Trevisan_M/0/1/0/all/0/1">M. Trevisan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Riffel_R/0/1/0/all/0/1">R. Riffel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chies_Santos_A/0/1/0/all/0/1">A. L. Chies-Santos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Furlanetto_C/0/1/0/all/0/1">C. Furlanetto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ricci_T/0/1/0/all/0/1">T. V. Ricci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lohmann_F/0/1/0/all/0/1">F. S. Lohmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Flores_Freitas_R/0/1/0/all/0/1">R. Flores-Freitas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mallmann_N/0/1/0/all/0/1">N. D. Mallmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alamo_Martinez_K/0/1/0/all/0/1">K. A. Alamo-Martínez</a>
We characterized the kinematics, morphology, and stellar population (SP)
properties of a sample of massive compact quiescent galaxies (MCGs) in the
MaNGA Survey (DR15), with the goal of constraining their formation, assembly
history and assessing their relation with non-compact quiescent galaxies. We
compared their properties with those of a control sample of median-sized
quiescent galaxies with similar effective velocity dispersions. MCGs have
elevated rotational support, as evidenced by a strong anti-correlation between
the Gauss-Hermite moment $h_3$ and $V/sigma$. In contrast, 30$%$ of control
sample galaxies (CSGs) are slow rotators, and fast-rotating CSGs generally show
a weak $h_3$-$V/sigma$ anti-correlation. MCGs and CSGs have similar ages, but
MCGs are more metal-rich and $alpha$-enhanced. Both MCGs and CSGs have shallow
negative metallicity gradients and flat [$alpha$/Fe] gradients. On average,
MCGs and CSGs have flat age gradients, but CSGs have a significantly larger
dispersion of gradient values. The kinematics and SP properties of MCGs suggest
that they experienced highly-dissipative gas-rich events, such as mergers,
followed by an intense, short, and centrally concentrated burst of star
formation, between 4 to 10 Gyr ago ($zsim0.4-2$), and had a quiet accretion
history since then. This sequence of events might be analogous to, although
less extreme than, the compaction events which formed compact quiescent
galaxies at $z sim 2$. The small sizes of MCGs, and the high efficiency and
short duration of their last star formation episode suggest that they are
descendants of compact post-starburst galaxies.
We characterized the kinematics, morphology, and stellar population (SP)
properties of a sample of massive compact quiescent galaxies (MCGs) in the
MaNGA Survey (DR15), with the goal of constraining their formation, assembly
history and assessing their relation with non-compact quiescent galaxies. We
compared their properties with those of a control sample of median-sized
quiescent galaxies with similar effective velocity dispersions. MCGs have
elevated rotational support, as evidenced by a strong anti-correlation between
the Gauss-Hermite moment $h_3$ and $V/sigma$. In contrast, 30$%$ of control
sample galaxies (CSGs) are slow rotators, and fast-rotating CSGs generally show
a weak $h_3$-$V/sigma$ anti-correlation. MCGs and CSGs have similar ages, but
MCGs are more metal-rich and $alpha$-enhanced. Both MCGs and CSGs have shallow
negative metallicity gradients and flat [$alpha$/Fe] gradients. On average,
MCGs and CSGs have flat age gradients, but CSGs have a significantly larger
dispersion of gradient values. The kinematics and SP properties of MCGs suggest
that they experienced highly-dissipative gas-rich events, such as mergers,
followed by an intense, short, and centrally concentrated burst of star
formation, between 4 to 10 Gyr ago ($zsim0.4-2$), and had a quiet accretion
history since then. This sequence of events might be analogous to, although
less extreme than, the compaction events which formed compact quiescent
galaxies at $z sim 2$. The small sizes of MCGs, and the high efficiency and
short duration of their last star formation episode suggest that they are
descendants of compact post-starburst galaxies.
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