With: V. Smolcic, A. Karim,, B. Magnelli, A.Zirm, M. Michalowski, P. Capak, K. Sheth, K. Schawinski, S. Wuyts, D. Sanders, A. Man, D. Lutz, J. Staguhn, S. Berta, H. McCracken, The highest redshift Sub-mm galaxies as progenitors of compact quiescent galaxies Sune Toft Dark Cosmology Centre Dark Group A. Zirm, A. Man, J.-K. Krogager, K. Olsen

“Connecting the Extreme”

Compact Quiescent Galaxies at z=2 (cQGs) Photometric surveys: The fraction of quiescent galaxies increases rapidly between z=3 and 2 At z=2, half of the most massive galaxies are quiescent with little ongoing star formation and evolved stellar populations n cQG =6.0±2.1 × Mpc -3 (Brammer++, 2011), Ilbert et al 2012)

Restframe optical absorption line spectroscopy Broad wavelength continuum fits: Post-Starburst with strong Balmer abs. Line indices: Metal rich, 1-2 Gyr old Velocity dispersions km/s (e.g. Toft et al 2012; van de Sande et al 2012, Onodera et al, 2012 )

Spectroscopic sample of z=2 cQGS COSMOS 3DHST+CANDLES Strong 4000A break  z-spec SED fit  M*, Av, age, zform Galfit HST/F160W  size “Complete” (Krogager, Zirm, Toft, Man & Brammer, ApJ (Submitted))

Mass-size relation (complete spectroscopic sample) (Krogager, Zirm, Toft & Brammer, 2013) 3DHST/CANDELS: The mass-size relation at z=2 is shifted to ~3 times smaller sizes at a given mass, with respect to the local relation (slope & scatter identical) >10 times larger stellar mass densities

Size evolution to z=0 Minor dry merging is likely responsible for some of the growth But other mechanisms also contribute (e.g. Carollo , Krogager ) (Newman++2013)

How did they form? NIR spectroscopy: Post-starburst spectra Baryon dominated Some dust (Av=0-1) Gyr -> zform>3 (Toft++2012, van de Sande++2012, Onodera++2012, K13) “Main sequence” star forming galaxies at z>3? SFR min >115 M  /yr from z=10 to zform >3 times higher than observed for z=3 LBGs (Carilli ) Number density of z>3 LBGs with M>10 11 M   << n cQG (Stark ) -> Progenitors must be dust obscured starbursts (Krogager++, 2013)

Dust obscured nuclear starbursts? (Hopkins ) (Wuyts ) Remnants very compact, concentrated (high sersic n) Sub-mm galaxies: Prime examples of high-z dusty nuclear starbursts Many authors have suggested a connection to cQGs (e.g. Tacconi++2006, Capak++2008, Toft++2009, Riechers++2013) Simulations of gas rich major mergers

SMGs as progenitors? cQG SMGs M*>10 11 M  >10 11 M  Int. Velocity (σ ★ )= km/sFWHM CO(1-0)= km/s =363 ±30 km/s =392 ±134 km/s =2.0 ± 0.2 kpc = 2.0 ± 0.3 kpc (2.3 ± 1.4) ×10 11 M  (2.5 ± 1.3) ×10 11 M  z form > 3 obs =2 (Tacconi et al 2006, 2008, Ivison et al 2011 van de Sande et al 2012, Toft et al 2012,, Krogager et al in prep,) At z=2 SMGs (probed through CO emission), have many similarities with cQGs (probed through their stars)

High redshift SMG sample COSMOS Aztec/JCMT/SMA sample “ Statistical Sample”: Flux (F 1.1mm >4.2mJy) & S/N (>4.5) –limited over 0.15 ☐ o Redshifts peak at =3 11 galaxies with z>3 (5 with spec-z) n(z>3) = 2.1 ± 0.4 × Mpc -3 (Smolcic et al 2012)

Redshift distribution match cQG (zform) SMG (zobs)

SMG surface brightness fits Fit 2D surface brightness profiles with galfit Stacked YJHK UltraVISTA images (WFC3/F160W where avail) Very compact, small sersic n >Half have bright multiple components

Mass-size relation z=2 cQG z>3 SMG

Duty cycle of SMG starburst 1: Assume : -SMGs are direct progenitors of cQGs -Each progenitor only undergo one SMG phase 2: Require number densities to match: Timescale of SMG starburst t burst (duty cycle) Consistent with Independent estimates t burst = Myr (gas depletion, clustering analysis, merger simulations) Relatively independent of IMF n SMG,z>3 = 2.1 ± 0.4 × Mpc -3 n q,z=2 = 6.0 ± 2.1 × Mpc -3

MIR-FIR SED fits Fit FIR SEDs with DL07 models Data: Spitzer MIPS, Herschel PACS, SPIRE, AzTEC, LABOCA, MAMBO, SMA, CARMA, PdBI Derive: LIR, SFR, Mdust, Mgas

Eddington Limited Bursts? (Younger et al 2010) z=2 cQG z>3 SMG Maximum SFR of cQGs during formation (Eddington limited burst)

Additional Stellar mass growth z=2 cQG z>3 SMG Z>3 stellar mass distribution broader than that of z=2 cQGs Ongoing starbursts in the SMG will increase their stellar mass ΔM ★ ~ M gas × η Star formation effeciency η~ (Hayward ) M gas from from M dust (derived from FIR SED fits) assuming a mass and metallicity dependent dust-to-gas ratio

Quenching by Active Galactic Nucleii? CDFS X-ray observations Deepest X-ray observations (4 million seconds) % of z=2 quiescent galaxies host AGN (Olsen, Rasmussen, Toft & Zirm, 2013 ) Stack: 50x4 Ms = 200 Ms 22%

“Connecting the Extreme” (Toft et al, 2014)

Summary Credit: HST press office

Extra slides

Star formation efficiency Gas fraction decrease by 10-15% from peak of starburst to when it is quenched Disc Merger (Hayward++, 2011)

Transition population (Barro++, 2012) Population of compact starforming galaxies at z~3 with depressed SFR and enhanced AGN fraction. Not quiet as massive, but sizes and number densities match z=2 cQGs

Descendants of z=2 SMGs (Bezanson ) Population of compact post starburst galaxies at z=1.5, with high stellar and dynamical masses and zform~2