Hiding in plain sight: An abundance of compact massive spheroids in the local Universe
Alister W. Graham, Bililign T. Dullo, Giulia A. D. Savorgnan

TL;DR
This study reveals a significant population of compact, massive spheroids in the local universe, challenging the notion that such galaxies have universally undergone dramatic size evolution since redshift ~2.
Contribution
It identifies and characterizes local compact massive spheroids that resemble high-redshift galaxies, suggesting less size evolution than previously thought.
Findings
21 spheroidal systems within 90 Mpc have R_e < 2 kpc and high stellar masses
The abundance of these spheroids in the local universe is higher than previously recognized
Some high-redshift spheroids may not have grown significantly in size since z ~ 2
Abstract
It has been widely remarked that compact, massive, elliptical-like galaxies are abundant at high redshifts but exceedingly rare in the Universe today, implying significant evolution such that their sizes at z ~ 2+/-0.6 have increased by factors of 3 to 6 to become today's massive elliptical galaxies. These claims have been based on studies which measured the half-light radii of galaxies as though they are all single component systems. Here we identify 21 spheroidal stellar systems within 90 Mpc that have half-light, major-axis radii R_e < ~2 kpc, stellar masses 0.7x10^{11} < M_*/M_Sun < 1.4x10^{11}, and Sersic indices typically around a value of n=2 to 3. This abundance of compact, massive spheroids in our own backyard - with a number density of 6.9x10^{-6} / Mpc^3 (or 3.5x10^{-5} / Mpc^3 per unit dex in stellar mass) - and with the same physical properties as the high-redshift…
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