Submillimeter Galaxies as Progenitors of Compact Quiescent Galaxies

Abstract

Three billion years after the big bang (at redshift z = 2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3 < z < 6). Simulations show that gas-rich major mergers can give rise to such starbursts which produce dense remnants. Sub-millimeter selected galaxies (SMGs) are prime examples of intense, gas-rich, starbursts. With a new, representative spectroscopic sample of compact quiescent galaxies at z = 2 and a statistically wellunderstood sample of SMGs, we show that z = 3 − 6 SMGs are consistent with being the progenitors of z = 2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42 +40 −29 Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star-formation. These results suggests a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star-formation through their appearance as high stellar-density galaxy cores and to their ultimate fate as giant ellipticals.

A SCUBA-2 survey of FeLoBAL QSOs. Are FeLoBALs in a ‘transition phase’ between ULIRGs and QSOs?

“…N is the number of sources in each sample. The last column is the weighted mean with the associated error obtained following the procedure described in Section 3.1. are consistent with the typical values of dust-rich systems such as sub-millimetre galaxies (SMGs), whose dust content is of the order of M dust = 9 × 10 9 M (e.g, Kovacs et al 2006;Toft et al 2014). …”

The clustering evolution of dusty star-forming galaxies

“…Di Matteo, Springel & Hernquist 2005), possibly resulting in compact quiescent galaxies (e.g. Toft et al 2014). It has been speculated that SMGs could then evolve on to the scaling relations observed for massive local elliptical galaxies, based on simple arguments involving the time-scale of the burst and the ageing of the stellar population (e.g.…”

(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies

“…From an observational point of view, this is supported by the clumpy or disturbed morphologies of SMGs and their complex kinematic signatures (e.g. Smail et al 1998;Tacconi et al 2008;Engel et al 2010;;Sharon et al 2013;Riechers et al 2013Riechers et al , 2014Hung et al 2013;Toft et al 2014;Neri et al 2014;Chen et al 2015). Engel et al (2010) concluded that most of the SMGs with IR luminosities of L IR > ∼ 5 × 10 12 L are probably major-merger systems (i.e.…”

“…with little or no ongoing star formation) elliptical galaxies seen in the present-day universe (e.g. Lilly et al 1999;Swinbank et al 2006;Fu et al 2013;Toft et al 2014;Simpson et al 2014). The existence of quiescent, red massive galaxies already at z ∼ 2−3 with old stellar populations indicates that these galaxies have experienced a short-lived starburst phase in their past (e.g.…”