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Next week: your final presentations We are happy to meet with you to discuss remaining issues, questions etc.

1 Nov 23, 2015 High-Redshift Galaxies III - Current Redshift Frontier - Gravitational Lensing - Star Formation/Stellar Mass Histories - Galaxy Main Sequence - Star Formation Law, Gas Fractions HW#10 is due today. Some final instructions are posted. Next week: your final presentations We are happy to meet with you to discuss remaining issues, questions etc. You have 10 minutes (practice) An electronic version of your final paper is due Dec 10 You should receive an about an on-line course evaluation; please fill it in

2 Nov 30: In class presentations Final presentation (10 minutes incl. questions) Next Week: Final Presentations (aim for min. 1 min per slide, so <~7 slides) try to prepare to speak freely, use your summary to memorize key issues us a copy by morning (make sure we get it) or bring your own laptop to avoid unexpected technical issues I use a Mac, so if you use another OS to prepare, a pdf may be safer in case

3 Massive, Active Galaxies at Very High Redshift Do Massive Galaxies, Supermassive Black Holes, Metals exist very early on? SZ effect: no massive (few times M sun ) galaxy clusters at z>1.5 or so density contrasts not high enough yet, cosmic structure formation not sufficiently mature 9-10 billion years ago At some earlier epochs, halos massive enough to form massive galaxies/ billion solar mass black holes should disappear. How and when? Expectations from hierarchical growth: massive galaxies that do exist early on should grow in the highest-density peaks/over-dense regions or even proto-clusters of galaxies. Evidence? Also, at some early point timescales become short to have formed significant amounts of metals. The first stars (Pop III) are metal-free, and have to pollute their environments to allow dust, CO etc. to form. The most massive halos may be enriched early on. Evidence?

Early SMBHs: Discovery of a Quasar at z>7 ULAS J1120+0641

085 2 x 10 9 M sun SMBH Would be among most massive TODAY

4 Early SMBHs: Discovery of a Quasar at z>7 ULAS J Most distant quasar known; z= x 10 9 M sun SMBH Would be among most massive TODAY RARE: Only z>7 quasar in 7500 deg 2 survey Need LSST+WFIRST for more? Mortlock et al. 2011

z>6 quasars: - M BH > 10 9 M sun J0129-0035 (z=5.78) J0840+5624 (z=5.84) J0927+2001 (z=5.

23) J1148+5251 (z=6.42) J1319+0950 (z=6.13) J1335+3533 (z=5.90) FIR-luminous quasars: - 12/12 detect.

5 z>6 quasars: - M BH > 10 9 M sun J (z=5.78) J (z=5.84) J (z=5.77) J (z=5.78) - 1/3: L FIR > L sun SFR > 1000 M sun /yr J (z=6.23) J (z=6.42) J (z=6.13) J (z=5.90) FIR-luminous quasars: - 12/12 detect. in CO - M gas > M sun J (z=5.89) J (z=6.18) J (z=6.04) J (z=6.00) z>6 QSOs have massive, heavily enriched host galaxies co-eval formation of SMBHs & hosts at t univ < 1 Gyr Walter et al. 2003, 2004, Carilli et al Riechers et al. 2009a, Wang et al. 2010, 2011, 2013 PdBI 6x15m interferometer

burst of gamma rays (GRB) detected by SWIFT satellite GRBs are

6 GRB090423: an Explosion at z=8.2 GRBs appear associated with star-forming galaxies Discovered via burst of gamma rays (GRB) detected by SWIFT satellite GRBs are believed associated with extraordinary explosions of stars: hypernovae Where is the hosting galaxy? Tanvir et al. 2009

22 mjy (3") - Berger et al. 2014 (ALMA) S(222GHz) <0.

7 (Lack of) GRB host galaxy at z=8.2 Millimeter afterglow/dust in GRB host? - Riechers et al (IRAM 30m): S(250GHz) < 0.96 mjy (3") [z=6.34 dusty galaxy: 14 mjy] - Walter et al (IRAM PdBI) S(205GHz) <0.22 mjy (3") - Berger et al (ALMA) S(222GHz) <0.033 mjy (3") L IR < 3x10 10 L sun SFR IR <5 M sun /yr UV/optical (HST) SFR UV <1M sun /yr optical/ir (Spitzer): M * <5x10 7 M sun very low-mass host galaxy? or individual very massive stellar explosion without a host galaxy?

Gravitational Lensing Strong GL as a tool for galaxy evolution: -

and fluxes (conserves surface brightness) Can observe distant galaxies

easily (HFF fields) Also: sensitive probe of dark matter halos of

and shape) In galaxy clusters, weak lensing is a powerful statistical

8 Gravitational Lensing Strong GL as a tool for galaxy evolution: - Randomly probes the same galaxy populations we know - Magnifies sizes and fluxes (conserves surface brightness) Can observe distant galaxies at higher spatial resolution Can detect faint galaxies much more easily (HFF fields) Also: sensitive probe of dark matter halos of foreground sources (total galaxy/cluster+halo mass, halo substructure and shape) In galaxy clusters, weak lensing is a powerful statistical probe lens selections: - radio surveys - optical morphologies - submillimeter fluxes

& Cosmic Lens All-Sky Survey (CLASS) high-resolution radio imaging (VLA/MERLIN/VLBI) of >16000 flat-spectrum radio sources Identified 22 multiply-imaged

9 Gravitational Lensing: Radio Surveys Predicted by Einstein in 1936, strong GL was first detected in 1979 (z=1.4 QSO SBS ) - Radio observations played an important role in confirming that this was indeed lensing : Jodrell Bank VLA Astrometric Survey (JVAS) & Cosmic Lens All-Sky Survey (CLASS) high-resolution radio imaging (VLA/MERLIN/VLBI) of >16000 flat-spectrum radio sources Identified 22 multiply-imaged gravitationally-lensed radio AGN at high redshift Many are lensed type-1 quasars, some are type-2 AGN Clear breakthrough, but limited success rate To date (2014), a fair number of the optically-faint sources do not have redshifts

Gravitational Lensing: Optical Surveys - Late

HST follow-up of radio lenses and optically-

, CfA-Arizona Space Telescope LEns Survey;

10 Gravitational Lensing: Optical Surveys - Late 1990s/early 2000s: rigorous high-resolution HST follow-up of radio lenses and optically- IDed quasars (e.g., CfA-Arizona Space Telescope LEns Survey; CASTLES) revealed ~100 lenses and ~20 quasar pairs. More recently, ground-based adaptive optics (e.g., Keck/NIRC2). - a handsome sample, but still biased toward AGN - Lensed galaxies: serendipitous discoveries (they are much more common), searches, e.g., in SDSS (seeing-limited, so biased towards larger separations, and shallow), and targeted galaxy cluster surveys have today revealed 100s of lensed galaxies that are not quasars/radio AGN

Also (since 2014) Lensed SN in Galaxies difference Dec 2010-Mar 2011 10-20 Nov 2014 Nov 3-20, 2014: SN in spiral arm

491 galaxy lensed by Hubble Frontier Field galaxy cluster Rare lensing configuration where entire galaxy is stretched

11 Also (since 2014) Lensed SN in Galaxies difference Dec 2010-Mar Nov 2014 Nov 3-20, 2014: SN in spiral arm of z=1.491 galaxy lensed by Hubble Frontier Field galaxy cluster Rare lensing configuration where entire galaxy is stretched widely (lensed by factor of 72) Galaxy is quadruply lensed by cluster, SN is quadruply lensed (~30x) by intervening early-type galaxy in cluster Kelly et al (submitted Nov 21) Sp1149 lensed galaxy images Days since Nov 3, 2014

Until ~2010, the largest submm surveys were 10s to maybe 100 arcmin 2 on the sky (limited detector sizes, challenging atmosphere) Large-area (>100-1000deg 2 ) Herschel/SPIRE 250/350/500µm surveys

12 Until ~2010, the largest submm surveys were 10s to maybe 100 arcmin 2 on the sky (limited detector sizes, challenging atmosphere) Large-area (> deg 2 ) Herschel/SPIRE 250/350/500µm surveys since 2010 have found an extended bright tail in the submm counts, too rare to be seen previously (also: SPT 1.4mm) Most are nearby star-forming galaxies (SDSS) or radio blazars sloping down (e.g., 20cm FIRST) The remaining, very rare sources (<1deg -2 ) look like optically faint dusty sources at high z (=SMGs?) Problem: SMGs are already very luminous, up to L FIR >10 13 L sun and maximum starbursts, and the likely progenitors of most massive galaxies today More far-ir-luminous galaxies should not exist Observed Counts 500µm Wardlow ea HerMES 7deg 2 FLS field µm Oliver ea SPIRE surveys: HerMES 110 deg 2 HeLMS 270 deg 2 HeRS 70 deg 2 H-ATLAS 550 deg 2

These are (dominantly) strongly lensed SMGs: high redshift high efficiency for lensing steep counts strong magnification bias Blain 1996; Negrello et al.

05 arcmin -2 & need alignment with massive foreground galaxy) Large-area (>100-1000deg 2 ) Herschel/SPIRE 250/350/500µm surveys ideal to find new population of rare, strongly lensed SMGs Wardlow ea.

13 These are (dominantly) strongly lensed SMGs: high redshift high efficiency for lensing steep counts strong magnification bias Blain 1996; Negrello et al. 2007, 2010 Observed Counts 500µm Introduce extended bright tail to counts, But: rare -- <1deg -2 on the sky (SMGs: 0.05 arcmin -2 & need alignment with massive foreground galaxy) Large-area (> deg 2 ) Herschel/SPIRE 250/350/500µm surveys ideal to find new population of rare, strongly lensed SMGs Wardlow ea Riechers ea very submm-bright starbursts, but never studied in detail before - completely new way of finding lenses, just requires a flux limit (i.e., no morph. bias) - past identifications of SMG redshifts, imaging etc. very slow due to sensitivity a factor10 in lensing saves a factor of 100 in observing time: ALMA science on a budget

14 The High-Redshift Galaxy Zoo 6 e.g., Franx et al. 2003, Daddi et al. 2004, Reddy et al. 2006, Papovich et al. 2006, Chapman et al. 2004, Grazian et al. 2007, Dey et al. 2008

15 Source Counts & Galaxy Evolution In a homogenous, Euclidean universe in which there is no evolution and the LF is constant, we expect the number of sources to increase as N(> S) # S -3/2 This is not what is observed evolving universe (and LF)

16 Galaxies do evolve The counts clearly lie ABOVE the no-evolution model

17 Source Counts: Proxy for Luminosity Function z = 4,5,6,7 Evolution in counts of LBGs observed, what is physical cause of evolution? - primary evolution is a shift in mag M * (0.7 mag in 0.7 Gyr over 4<z<6) - change in shape of LF less secure (but $=-1.7 is very steep) - evolution can be explained by models driven by halo mergers Stark, Loeb & Ellis 2007, Bouwens et al. 2007

18 Stellar Masses & Ages: Comparing z~5 & z~3 LBGs z~5 z~3 z~5 z~3 For similarly-luminous LBGs, those at z~5 are younger and less massive than at z~3 Witnessing stellar mass buildup with cosmic time Verma et al. (2007)

19 Star formation history of the universe The Madau-Lilly Plot describes the SFR of the Universe within a comoving volume element as a function of redshift. Madau et al. 1996, MNRAS, 283, Note that heavy element production tracks the star formation rate Steidel et al. 1999, ApJ, 519, 1

20 The rate of star formation in galaxies was much higher in the past than it is today. ( times) About half the stellar mass in the universe today were built up at z=1-3 ( epoch of galaxy assembly ) The SFR density then declines towards very high z Star formation rate density

21 Main Issues in Assembling " the Cosmic Star Formation History Different redshifts: different technique for finding galaxies and different SFR estimates Correction for dust extinction Which fraction of <SFR> comes from faint but numerous galaxies (extrapolating the LF)? Count the effect of the UV photons on the IGM (next week)

history of the universe cosmic star formation big bang recombination z~1000 0.0003 Gyr Volume density of star formation in galaxies as f(cosmic time) dark ages reionization z~15-1000 0.0003-0.

22 history of the universe cosmic star formation big bang recombination z~ Gyr Volume density of star formation in galaxies as f(cosmic time) dark ages reionization z~ Gyr z~ Gyr Epoch of galaxy assembly Present day?" First galaxies Bouwens et al Stellar Light Stars+Dust quasar/galaxy build-up today s universe z<~6 >1 Gyr z~ Gyr Star Formation in Galaxies at High Redshift: - A few billion years ago, galaxies in the universe formed ~30x more stars than today (making up the stars we see now) - The most intensely starbursts at high z form 10-30x more stars than the most extreme examples today sites of star formation enshrouded by dust, absorbing a fraction of the stellar light (which is re-radiated in the rest-frame far-infrared)

23 How important is this in general? ~50% of starlight from galaxies in the Universe received at Earth is absorbed by dust Some (very distant) dusty galaxies are not seen in deep Hubble images at all To understand the cosmic history of star formation in galaxies, dust is important

Cosmic Infrared Background COBE detected a cosmic IR background (CIB) in 1996, suggesting the existence of a population of dusty galaxies at high redshift.

24 Cosmic Infrared Background COBE detected a cosmic IR background (CIB) in 1996, suggesting the existence of a population of dusty galaxies at high redshift. Multiple groups have used SCUBA/ MAMBO (850µm/1.2mm) to search for the sources making up this background. But they cannot be resolved easily (need higher resolution) Blain et al. 2002, PhRep, 369, 111 Lagache et al ARA&A Dole et al. 2006, A&A, 451, 417

25 Stellar light deficiency absorbed by dust Highly starforming galaxies: - Brighter - Lower Optical/ IR ratio Dustier Important for CIB CIB vs. Galaxy SED Dust bump re-processed stellar light Passive red galaxies: - Fainter - Higher Optical/ IR ratio COB/CIB: Integrated over all galaxies Lagache et al ARA&A Lyman limit UV light young, hot stars Stellar bump old stars

$Star Formation History The dust-obscured fraction of star formation in the universe is significant UV/optical studies miss substantial fraction of cosmic star formation New phenomenon:$

26 CIB vs. Star Formation History The dust-obscured fraction of star formation in the universe is significant UV/optical studies miss substantial fraction of cosmic star formation New phenomenon: distant, very IR-luminous (observed-frame submm) galaxies Epoch of galaxy assembly?" Present day First galaxies The (sub)mm is a key wavelength regime to understand galaxy evolution

27 ALMA Deep Fields

28 ALMA Deep Fields

29 Negative K-correction The K-correction is the correction we apply to the observed flux of an object of a given SED that accounts for its redshift. The K correction at the mm and submm at % > 250 µm, which yields a flux density that is almost independent of redshift.

30 Flux from dusty galaxies Dust emissivity S & # & 2+' where ' ~ 1 2 (thermal emission plus dust grain properties)

Why did the global SFR decrease towards the present epoch?

insufficient, only ~20% of galaxies at z~0.

31 Why did the global SFR decrease towards the present epoch? At high z the SFR was >10x higher than today (Lilly et al. 1996, Madau et al. 1996) Did it drop because there were fewer merger-driven starbursts? insufficient, only ~20% of galaxies at z~0.75 are visibly interacting (but: lower limit due to morphological classification) Did it drop because quiescent disk galaxies today form fewer stars? yes, but why? (f gas, discuss later)

32 The rate at which stars form over time must correspond to the buildup of the stellar masses of galaxies Individual galaxies can grow in mass by - forming new stars - coalescence (merging) of pre-existing bits Merger rate? - of order 1 major merger since z~1 for massive galaxies Star formation => stellar mass

Galaxy Mass Function at Earlier Epochs At present: galaxy mass function is Schechter function most stars in M gal =10 10.

33 Galaxy Mass Function at Earlier Epochs At present: galaxy mass function is Schechter function most stars in M gal = M sun At earlier epochs: Define M * -limited sample, independent of SFR (which brightens galaxies) near-ir selection is needed Results: Galaxy mass function looks similar 0<z<4 characteristic mass was only slightly lower at high-z Co-moving density was considerably lower Most stars were always in the most massive galaxies At least for z<4, since when 95% of all stars formed e.g. Marchesini et al. 2009

34 Connecting the BzK, LBG and DRG Populations SF Density Contributions Distribution of M>10 11 M galaxies LBG DRG LBG Reddy et al. (2005) - sbzk and LBGs are (largely) identical populations Kong et al. (2006) - Clustering of sbzk and pbzk galaxies is identical, suggesting same population and SF is simply transient van Dokkum et al. (2006) - LBGs constitute only 17% of massive galaxies

The star formation main sequence of galaxies The general high-redshift galaxy population: BzK, BX/BM, LBG-selected galaxies ( typical / normal ), SMGs ( starbursts ) - There appears to be a relation

35 The star formation main sequence of galaxies The general high-redshift galaxy population: BzK, BX/BM, LBG-selected galaxies ( typical / normal ), SMGs ( starbursts ) - There appears to be a relation between SFR and M * for actively starforming galaxies, a main sequence (MS) of star formation - passive galaxies fill the triangular region below - Merger-driven starbursts deviate from the MS (few times higher SFR) - The normalization appears to evolve with redshift towards higher SFR (caution: there are some mergers/starbursts on the MS, but they are a minority) Daddi et al. 2007, Noeske et al. 2007

Dominik A. Riechers Cornell University

JVLA ALMA CCAT First year of full science Finishing construction The next big thing The Interstellar Medium in High Redshift Galaxies Dominik A. Riechers Cornell University Phases of the ISM MPIA Summer