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

Disc cloaking: Establishing a lower limit to the number density of local compact massive spheroids/bulges and the potential fate of some high-z red nuggets / Hon, DSH; Graham, AW; Davis, BL; Marconi, A. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - ELETTRONICO. - 514:(2022), pp. 3410-3451. [10.1093/mnras/stac1171]

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

Marconi, A
2022

Abstract

The near-absence of compact massive quiescent galaxies in the local Universe implies a size evolution since z similar to 2.5. It is often theorized that such 'red nuggets' have evolved into today's elliptical (E) galaxies via an E-to-E transformation. We examine an alternative scenario in which a red nugget develops a rotational disc through mergers and accretion, say, at 1 less than or similar to z less than or similar to 2, thereby cloaking the nugget as the extant bulge/spheroid component of a larger, now old, galaxy. We have performed detailed, physically motivated, multicomponent decompositions of a volume-limited sample of 103 massive (M-*/M-circle dot greater than or similar to 1 x 10(11)) galaxies within 110 Mpc. Many less massive nearby galaxies are known to be 'fast-rotators' with discs. Among our 28 galaxies with existing elliptical classifications, we found that 18 have large-scale discs, and two have intermediate-scale discs, and are reclassified here as lenticulars (S0) and elliculars (ES). The local spheroid stellar mass function, size-mass diagram and bulge-to-total (B/T) flux ratio are presented. We report lower limits for the volume number density of compact massive spheroids, n(c,) (Sph) similar to (0.17-1.2) x 10(-4) Mpc(-3), based on different definitions of 'red nuggets' in the literature. Similar number densities of local compact massive bulges were reported by de la Rosa et al. using automated two-component decompositions and their existence is now abundantly clear with our multicomponent decompositions. We find disc-cloaking to be a salient alternative for galaxy evolution. In particular, instead of an E-to-E process, disc growth is the dominant evolutionary pathway for at least low-mass (1 x 10(10) < M-*/M-circle dot (sic) 4 x 10(10)) red nuggets, while our current lower limits are within an alluring factor of a few of the peak abundance of high-mass red nuggets at 1 less than or similar to z less than or similar to 2.
514
3410
3451
Hon, DSH; Graham, AW; Davis, BL; Marconi, A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2158/1286053
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