SLIDE 1 JVLA ALMA
Herschel
CCAT
Finishing construction First year of full science The next big thing
R.I.P .!
Dynamics of Disk Galaxies, Seoul, Korea 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)!
Dominik A. Riechers
Cornell University
Gas Dynamics in High-Redshift Galaxies
SLIDE 2 reionization! today’s! universe! quasar/galaxy! build-up! ‘dark ages’! cosmic star formation! history of the universe! big bang! recombination!
z~8-15! 0.3-1 Gyr! z~15-1000! 0.0003-0.3 Gyr! z<~8! >1 Gyr! z~0! 13.8 Gyr! z~1000! 0.0003 Gyr!
?
First galaxies! “Epoch of galaxy assembly”! Present day!
Volume density of star formation in galaxies as f(cosmic time)!
Stellar Light Stars+Dust
Star Formation in Galaxies at High Redshift is Exciting:!
!
- A few billion years ago, galaxies in the universe formed !
~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?! !
sites of star formation enshrouded by dust, absorbing a fraction of the stellar light (which is re-radiated in the rest-frame far-infrared)
!
Bouwens et al. 2011!
SLIDE 3
Carilli & Walter 2013 ARAA; after Daddi et al. 2010, Genzel et al. 2010!
Simplest Version of “Star Formation Law”: Spatially Integrated Observables
L’CO vs. LFIR
as a surrogate for
Mgas 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? “efficient” star-formers
SLIDE 4
Carilli & Walter 2013 ARAA; after Magdis et al. 2012!
const.? Even “main sequence” galaxies (defined as typical SFR/M*(z)) show 10-30x higher gas fractions at z=1-3 compared to present day ! Increased SF history driven by high gas fractions of galaxies (not by extreme merger rates) ! LFIR = 1012 Lsun is the new “normal” ! LFIR = 1013 Lsun are high starbursts (SMGs) ! Star formation is elevated, but underlying physics are the same ! Gas depletion makes z=0 “special”
SLIDE 5
! 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!
GOALS! cosmic web! cold gas streams! massive galaxy!
Images: Springel, Dekel, Tacconi!
Major mergers of multiple disks (fast growth) Gas accretion onto disks (slow growth)
SLIDE 6 Riechers et al. 2013b, Nature! Herschel/SPIRE “ultra-red” source at 250/350/500µm:!
!
Galaxy confirmed! … at z=6.3369 !!!
!
Detect! 7 CO lines! 7 H2O lines! H2O+! NH3 (absorption)! OH! OH+ (absorption)! [CI]! [CII]! Hints of others…! ! Highly enriched! ! Gray line is best existing spectrum
Observed 880 million years after the Big Bang (current age: 13.8 billion yrs)
SLIDE 7
Riechers et al. 2013b! 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!
SLIDE 8 Riechers et al. (2011d, 2011f); see also: Ivison et al. (2011)!
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?!
Early stage
~30kpc & 750km/s ! separation!
Intermediate stage
~20kpc & <100km/s ! separation!
Late stage
7-15kpc nucleus & tidal structure ! single broad, multi-peaked line! abundant low-excitation gas!
Mgas = 1-20 x 1010 Msun & SFR >500 Msunyr-1
!
SLIDE 9
VLA Key Program (0.15”/1.0kpc resolution @ 7mm) ! ! Clustered, massive galaxy formation at tuniv ~ 1.6Gyr! + +
GN20.2a z=4.051! GN20.2b z=4.056!
GN20 z=4.055! Carilli et al. (2010, 2011); Hodge et al. (2012, 2013)! CO J=2-1! Jansky VLA! Keck 10m deep
GN20.2a!
30 kpc!
SLIDE 10 +
- massive starburst: SFR ~ 3000 Msun/yr!
- CO: large, rotating gas disk (~14 kpc across)!
i=30o; vmax=575 km/s; "disp ~ 100 km/s!
- Mdyn = 5.4 x 1011 Msun (~25% molecular gas)!
- Disk punctuated by kpc-size clumps:
Mdyn ~ Mgas ~ 109 Msun (90-160 km/s FWHM)!
CO Intensity! velocity field!
1”!
+250 km/s!
1kpc “clump”! CO spectra!
GN20 z=4.055!
SLIDE 11 SMG
rotating gas disk
QSO
companion galaxy
+500km/s
Carilli et al. 2013!
Lyman-alpha image!
ALMA!
20 kpc!
! Clearly a tidally complex system, but obscured starburst consistent w/ massive gas disk!
[CII] 158µm ISM cooling line!
Ly-alpha emitter/ tidal gas stream QSO outflow
20min, 16 ants (~2min full ALMA)!
SLIDE 12
! Most Distant Massive Starburst Galaxy (SMG) known (2010-2013):! MH2 = 5.3 x 1010 Msun SFR >1800 Msun/yr!
!
! Most Distant Galaxy Proto-Cluster:!
11 Lyman-break galaxy companions within r~2 Mpc, structure extends to >14 Mpc!
2x2 arcmin2 Riechers, Capak et al. 2010, ApJ! Capak, Riechers et al. 2011, Nature!
JVLA! PdBI! PdBI! CO spectroscopy!
COSMOS/AzTEC-3 (z=5.3)
+ +
HST! JVLA! PdBI! (no radio detection)!
SLIDE 13
- " 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
