Disc cloaking: Establishing a lower limit to the number density of local compact massive spheroids/bulges and the potential fate of some high-<i>z</i> red nuggets

ABSTRACT The near-absence of compact massive quiescent galaxies in the local Universe implies a size evolution since z ? 2.5. It is often theorized that such ‘red nuggets’ have evolved into today’s elliptical (E) via an E-to-E transformation. We examine alternative scenario which red nugget develops rotational disc through mergers and accretion, say, at 1 ? 2, thereby cloaking as extant bulge/spheroid component larger, now old, galaxy. performed detailed, physically motivated, multicomponent decompositions volume-limited sample 103 ($M_*/\rm M_{\odot } \gtrsim 1\times 10^{11}$) within 110 Mpc. Many less nearby are known to be ‘fast-rotators’ with discs. Among our 28 existing classifications, we found 18 large-scale discs, two intermediate-scale reclassified here lenticulars (S0) elliculars (ES). spheroid stellar mass function, size–mass diagram bulge-to-total (B/T) flux ratio presented. report lower limits for volume number density spheroids, nc, Sph (0.17–$1.2) \times 10^{-4}\, \rm Mpc^{-3}$, based on different definitions literature. Similar densities bulges were reported by de la Rosa et al. using automated two-component their existence abundantly clear decompositions. find disc-cloaking salient galaxy evolution. In particular, instead process, growth dominant evolutionary pathway least low-mass ($1\times 10^{10}\lt M_*/\rm \lessapprox 4 10^{10}$) nuggets, while current alluring factor few peak abundance high-mass nuggets 2.