JVLA � ALMA � CCAT � First year of full science � The next big thing � Finishing construction � Gas Dynamics in High-Redshift Galaxies Dominik A. Riechers Cornell University Dynamics of Disk Galaxies, Seoul, Korea Herschel � R.I.P . ! October 22, 2013 � with: ! C. Carilli (NRAO), F. Walter, J. Hodge (MPIA), P . Capak, N. Scoville (Caltech), E. Daddi (CEA), C. Sharon (Cornell), J. Wagg (ESO) !
history of the universe ! cosmic star formation ! big bang ! Volume density of star formation in galaxies as f(cosmic time) ! z~1000 ! recombination ! 0.0003 Gyr ! z~15-1000 ! Bouwens et al. 2011 ! ‘ dark ages ’ ! 0.0003-0.3 Gyr ! “Epoch of ? � galaxy assembly” ! z~8-15 ! reionization ! 0.3-1 Gyr ! Stellar Light Stars+Dust First galaxies ! Present day ! Star Formation in Galaxies at High Redshift is Exciting: ! ! z<~8 ! quasar/galaxy ! >1 Gyr ! - A few billion years ago, galaxies in the universe formed ! build-up ! ~30x more stars than today (making up the stars we see now) ! …why? ! - The most intensely starbursts at high z form 10-30x more stars than the most extreme examples today …why? ! ! z~0 ! today ’ s ! 13.8 Gyr ! sites of star formation enshrouded by dust , absorbing a fraction of universe ! the stellar light (which is re-radiated in the rest-frame far-infrared) !
Simplest Version of “efficient” “Star Formation Law”: star-formers Spatially Integrated Observables L’ CO vs. L FIR as a surrogate for M gas vs. SFR One super-linear relation or Two sequences ( quiescent / starburst ) Bimodal or running conversion factor …many subtleties, but: High-z galaxies higher on both axes Quiescent and Starburst Galaxies ! Disk galaxies vs. major mergers , secular evolution vs. bursts of SF? Carilli & Walter 2013 ARAA; after Daddi et al. 2010, Genzel et al. 2010 !
Even “main sequence” galaxies (defined as typical SFR/M * (z)) show 10-30x higher gas fractions at z=1-3 compared to present day const.? ! Increased SF history driven by high gas fractions of galaxies (not by extreme merger rates) ! L FIR = 10 12 L sun is the new “normal” ! L FIR = 10 13 L sun are high starbursts (SMGs) ! Star formation is elevated, but underlying physics are the same ! Gas depletion makes z=0 “special” Carilli & Walter 2013 ARAA; after Magdis et al. 2012 !
! Star formation/M * buildup at early cosmic times likely occurs through steady “cold mode” gas accretion, minor mergers, and major mergers ! ! Do these IR-luminous “normal” and “starburst” galaxies correspond to different modes of star formation in galaxies with similarly high gas mass fractions? ! ! Let’s look at some examples of extremely IR-luminous galaxies at high redshift ! Major mergers of multiple disks (fast growth) Gas accretion onto disks (slow growth) cosmic web ! massive galaxy ! GOALS ! cold gas streams ! Images: Springel, Dekel, Tacconi !
Herschel/SPIRE “ultra-red” source at 250/350/500µm: ! ! Galaxy confirmed ! … at z=6.3369 !! ! ! Detect ! 7 CO lines ! 7 H 2 O lines ! H 2 O + ! NH 3 (absorption) ! OH ! OH + (absorption) ! [CI] ! [CII] ! Hints of others… ! ! Highly enriched ! ! Gray line is best existing spectrum of nearby starburst ! Observed 880 million years after the Big Bang (current age: 13.8 billion yrs) Riechers et al. 2013b, Nature !
Almost as many stars as the Milky Way ! Similar total mass, already at z=6.34 ! 40x more gas ! 2000x more star formation ! …and ~20x more star formation ! than extreme nearby starburst ! ! …consistent with a so-called ! ! “maximum starburst” galaxy ! Also: a compact (~3.5kpc), high velocity dispersion gas reservoir ! ! High star formation rate likely driven by a major merger ! ! An extraordinary starburst, even compared to others at high z ! Riechers et al. 2013b !
Riechers et al. (2011d, 2011f); see also: Ivison et al. (2011) ! Early stage � Intermediate stage � Late stage � ~30kpc & 750km/s ! ~20kpc & <100km/s ! 7-15kpc nucleus & tidal structure ! separation ! separation ! single broad, multi-peaked line ! M gas = 1-20 x 10 10 M sun & SFR >500 M sun yr -1 abundant low-excitation gas ! ! Submillimeter Galaxies: Gas-Rich Starbursts along the “Merger Sequence” at z>2 ! ! Nearby major mergers show increased SF efficiency relative to disks ! SMGs are “scaled up” versions of nearby IR-luminous galaxies/mergers ! ! …but is this true in general for high-redshift galaxies with high SF efficiencies? !
GN20.2b GN20.2a GN20 z=4.056 ! z=4.051 ! z=4.055 ! + + Keck 10m deep 30 kpc ! optical spectrum ! CO J =2-1 ! Jansky VLA ! GN20.2a ! • Jansky VLA Key Program (0.15”/1.0kpc resolution @ 7mm) ! ! Clustered, massive galaxy formation at t univ ~ 1.6Gyr ! Carilli et al. (2010, 2011); Hodge et al. (2012, 2013) !
CO Intensity ! GN20 z=4.055 ! 1 ” ! 1kpc “clump” ! CO spectra ! • massive starburst: SFR ~ 3000 M sun /yr ! -250 km/s ! • CO: large, rotating gas disk (~14 kpc across) ! i=30 o ; v max =575 km/s; " disp ~ 100 km/s ! • M dyn = 5.4 x 10 11 M sun (~25% molecular gas) ! • Disk punctuated by kpc-size clumps: +250 km/s ! M dyn ~ M gas ~ 10 9 M sun (90-160 km/s FWHM) ! velocity field ! +
[CII] 158µm ISM cooling line ! Carilli et al. 2013 ! -500km/s SMG optically obscured rotating gas disk Ly-alpha emitter/ 20 kpc ! tidal gas stream Lyman-alpha image ! 20min, 16 ants (~2min full ALMA) ! QSO ALMA ! QSO outflow companion galaxy +500km/s ! Clearly a tidally complex system, but obscured starburst consistent w/ massive gas disk !
CO spectroscopy ! 2x2 arcmin 2 JVLA ! PdBI ! PdBI ! COSMOS/AzTEC-3 (z=5.3) � (no radio detection) ! ! Most Distant Massive Starburst Galaxy (SMG) known (2010-2013) : ! M H2 = 5.3 x 10 10 M sun SFR >1800 M sun /yr ! ! ! Most Distant Galaxy Proto-Cluster : ! 11 Lyman-break galaxy companions within r~2 Mpc, structure extends to >14 Mpc ! HST ! JVLA ! PdBI ! Riechers, Capak et al. 2010, ApJ ! + + Capak, Riechers et al. 2011, Nature !
� � " star formation activity at high redshift: - high-redshift galaxies show an order-of-magnitude higher star formation activity relative to galaxies in the nearby Universe - these high star formation rates appears to be related to a similar rise in the gas fractions of galaxies toward early epochs - high gas fractions are found for “typical” galaxies and starbursts alike - this high gas content is perhaps related to high gas accretion rates " star formation efficiencies at high redshift: • the most efficiently star-forming galaxies are commonly mergers • some fraction, however, show evidence for extended, clumpy gas disks & wide-spread star formation, even among extreme starbursts • high-z studies so far limited to very massive systems, but ALMA enables studies of gas dynamics for “typical” high-z galaxies at z>5 • the [CII] 158 ! m line will be the “workhorse” diagnostic for dynamically resolved ISM studies on sub-kpc scales at z=1-8 ! ALMA will provide detailed insight in disk dynamics at high redshift
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