The VLA-COSMOS survey: The VLA-COSMOS survey: Tracing star-forming and AGN Tracing star-forming and AGN galaxies through cosmic timegalaxies through cosmic time

Vernesa Smolčić (Caltech)Vernesa Smolčić (Caltech)E. Schinnerer (MPIA), C.L. Carilli (NRAO), M. Bondi (INAF), E. Schinnerer (MPIA), C.L. Carilli (NRAO), M. Bondi (INAF), P. Cilliegi (INAF), G. Zamorani (INAF), K. Jahnke (MPIA), M. P. Cilliegi (INAF), G. Zamorani (INAF), K. Jahnke (MPIA), M.

Sargent (MPIA) & the (VLA-)COSMOS collaborationSargent (MPIA) & the (VLA-)COSMOS collaboration

Radio emission at 1.4 GHz (20cm) Radio emission at 1.4 GHz (20cm) Dominated by synchrotron radiationDominated by synchrotron radiation

Two dominant populations in extragalactic Two dominant populations in extragalactic radio surveys:radio surveys:

11 Star forming (Star forming (SFSF) galaxies) galaxies

Radio emission is not sensitive to dustRadio emission is not sensitive to dust

22 Active galactic nuclei (Active galactic nuclei (AGNAGN))Radio emission directly traces the population of low radio Radio emission directly traces the population of low radio power AGN, deemed important for galaxy formationpower AGN, deemed important for galaxy formation

Condon 1992

1.4 GHz

20 cm

1.4 GHz

z ~ 5

M82

Thermal (free-free) emission (radio)

The

rmal

dus

t em

issi

on (F

IR)

Synchrotron emission

(radio)

Condon 1992

van der Kruit 1971; Helou et al. 1985; Condon et al. 1992, Yun et al. 2001; Bell 2003; Obric et al. 2006; Mauch & Sadler 2007

Bell 2003

Radio – IR correlation

Star forming galaxiesStar forming galaxies

Star formation rate density [M / yr / Mpc3]

Short-wavelength radiation (e.g. UV) sensitive to dust radio emission overcomes this bias

Compilation based on different star formation estimators (Hα, OII, UV; Hopkins 2004)

Cosmic star formation historyCosmic star formation history

AGN feedbackAGN feedback

Faber et al. 2007

galaxy cluster MS0735.6+7421 (z=0.2); white = HST, blue = Chandra, red = VLA; NASA.gov

1. QUASAR MODE- Merger driven- Vigorous BH mass growth- Qusar wind gas expells gas out of the galaxy’s center

termination of quasar & starburst phase- Not necessarily linked to radio outflows

2. RADIO MODE- Once a static hot gas halo forms around the galaxy- Modest BH mass growth- Radio outflows heat surrounding gas truncation of further stellar mass growth

Allows good reproduction of observed galaxy properties

Different phases of galaxy merger (gas); MPA

Croton et al. 2006; Bower et al. 2006; Sijacki et al. 2006, Hopkins et al. 2006…

Allows good reproduction of observed galaxy properties

1. Quasar mode 2. Radio mode

Luminosity function of galaxies

Croton et al. 2006

Croton et al. 2006: mean BH accretion rate per unit volume averaged over the entire simulation

This theoretically derivedcurve can directly be inferred from radio observations

HOWEVERHOWEVER

Deep radio data Deep radio data (rms<15μJy/beam)(rms<15μJy/beam) of of a a large large sample needed sample needed !!!!!!

The faint (<1 mJy) radio population The faint (<1 mJy) radio population 1.4 GHz (20 cm) differential radio source counts (normalized to Euclidian 1.4 GHz (20 cm) differential radio source counts (normalized to Euclidian

space) flatten below 1 mJy space) flatten below 1 mJy

rise of a new population not contributing significantly at higher flux levelsrise of a new population not contributing significantly at higher flux levels The composition of this faint radio population is highly controversial The composition of this faint radio population is highly controversial (Seymour et (Seymour et

al. 2004, 2008, Simpson et al. 2006, Fomalont et al. 2007, Padovani et al. 2007, Smolcic et al. 2008, Kellermann et al. al. 2004, 2008, Simpson et al. 2006, Fomalont et al. 2007, Padovani et al. 2007, Smolcic et al. 2008, Kellermann et al.

2008)2008)

Bondi et al. (2008) S (mJy)

n S

2.5

(sr-1

Jy1.

5 )

FIRST / NVSS Cambridge

Differential 20 cm source counts (norm. to Euclidian space)

sub-mJy radio population:

star forming gals + low-power AGN

Robust SF/AGN classfier needed

!!!!!!

The COSMOS SurveyThe COSMOS Survey

COSMOS overview (Scoville et al. 2007)

2 □O equatorial field

X-ray to radio imaging (~30 bands) galaxy photo-z accuracy, 0.7% (Ilbert et al 2008)

quasar photo-z accuracy, 1.5% (Salvato et al. 2008)

spectroscopy (VLT-VIMOS + Magellan-IMACS)

The COSMOS surveyThe COSMOS survey

5σ depth for all existing data and the expected 5σ depth for upcoming or ongoing guaranteed time observations

VLA-COSMOS 20 cm surveyVLA-COSMOS 20 cm survey NRAO Very Large ArrayNRAO Very Large Array

VLA-COSMOS team: Schinnerer (PI) Smolcic, Carilli, Bondi, Ciliegi, Scoville, Bertoldi, Blain, Impey, Jahnke, Koekemoer, Le Fevre, Urry, Martinez Sansigre, Wang, Datta

Pilot project (10hr): A array (Schinnerer et al. 2004) ~ 250 sources (catalog - public) ~ 1 sqrdeg; rms ~ 30 Jy/beam

Large project (275hr): A+C array (Schinnerer et al. 2007) ~ 3,642 sources (catalog - public) ~ 2(1) sqrdeg; mean rms ~ 15(10) Jy/beam; Deep project (62hr): A array ~ 1 sqrdeg; rms ~ 7-8 Jy/beam (central 30’)

Radio view of COSMOS field: Radio view of COSMOS field: NRAO Very Large ArrayNRAO Very Large Array

VLA-COSMOS core team: Schinnerer, Smolčić, Carilli, Bondi, Ciliegi, Scoville, Bertoldi, Blain, Impey, Jahnke, Koekemoer, Le Fevre, Urry, Martínez Sansigre, Wang, Datta, Riechers

Large project (275hr): Schinnerer et al. (2004, 2007) ~ 2,400 sources (catalog - public) ~ 2 □O; mean rms ~ 10 Jy/beam, 1.5” resolution unique complementary COSMOS data set enabling studies of AGN/SF evolution through cosmic times

Deep project (62hr): Schinnerer et al. (to be submitted) ~ 1 □O; rms ~ 7 Jy/beam

327 MHz project (24hr): Smolčić et al. (in prep) ~ 2 □O; rms ~ 0.5 mJy/beam

What have we (so far) learned What have we (so far) learned from VLA-COSMOS?from VLA-COSMOS?

The composition of the sub-mJy radio population The composition of the sub-mJy radio population

Bondi et al. (2008) S (mJy)

n S

2.5

(sr-1

Jy1.

5 )

Differential 20 cm source counts

FIRST / NVSS CambridgeBaldwin-Phillips-Terlevich (1981) diagram

Kauffmann et al. (2003), Kewley et al. (2001,2006), Obrić et al. (2006), Smolčić et al. (2006, 2008a)

New rest-frame color-based method for separating SF from low-luminosity AGN galaxies (i.e. Seyfert, LINERs; Smolčić et al. 2008a)

applied to VLA-COSMOS data

Sub-mJy radio population:

1) not dominated by star forming galaxies

2) fair mix of SF and (low-L) AGN galaxies

Smolčić et al. (2008; ApJS; 177, 14)

@ z≤1.3: ~ 350 SF & ~ 600 AGN gals.

The radio - (F)IR correlationThe radio - (F)IR correlation Current focus onCurrent focus on (Sargent et al., in (Sargent et al., in

prep.):prep.):- quantification of selection effects in quantification of selection effects in

view of future deep EVLA & Herschel view of future deep EVLA & Herschel datadata

- statistically sound treatment of flux statistically sound treatment of flux limits using survival analysislimits using survival analysis

evolution of radio-IR relation for star evolution of radio-IR relation for star forming systems out to z~1forming systems out to z~1

Future work:

- Effects of environment (E. Murphy et al., in prep) - separation of star forming systems into different classes of objects (e.g. optical morphology, mass)- stacking of radio population at faint IR fluxes

Little or no evolution of the IR/radio ratios at least out to z~1

Smolčić et al. (2008); Sargent et al. (in prep)

The dust-unbiased cosmic star The dust-unbiased cosmic star formation history @ z≤1.3 from formation history @ z≤1.3 from

the VLA-COSMOS surveythe VLA-COSMOS survey

Good agreement between Good agreement between VLA-COSMOS andVLA-COSMOS and previous radio results previous radio results

(1 order of magnitude (1 order of magnitude smaller sample; smaller sample; Haarsma Haarsma

et al. 2000et al. 2000)) other SFRD estimates other SFRD estimates

from Hfrom Hαα, OII, UV, IR, OII, UV, IR

with dust correction with dust correction applied where neededapplied where needed

Smolčić et al. (2009, ApJ, 690, 610)

Dust attenuation at intermediate redshifts is well understood

20cm lumiosity functions for VLA-COSMOS star forming galaxies (blue)

Cosmic star formation history

Probing SFRs at high z via stackingProbing SFRs at high z via stackingCOSMOS Lyman break galaxy sample of Lee, Capak et al.

Carilli et al. (2008; ApJ, 689, 883)

Stacking detection:Stacking detection:U band drop-outs (2.5 < z < 3.5)U band drop-outs (2.5 < z < 3.5)

Median flux: 0.90 ± 0.21 μJyMedian flux: 0.90 ± 0.21 μJy

<SFR<SFRradioradio> = 31 ± 7 M> = 31 ± 7 MSUNSUN/yr/yr

<SFR<SFRUVUV> ~ 17 M> ~ 17 MSUNSUN/yr/yr

dust attenuation factor ~1.8 dust attenuation factor ~1.8 <<<< standard attenuation factor of 5 standard attenuation factor of 5 (Steidel et al. 1999, Adelberger & Steidel 2000, Reddy & Steidel 2004)

Dust attenuation at high redshifts may be smaller than at lower redshifts

Star formation history derived from UDS/UKIDSS BzK selected galaxies stacked in radio (Dunne et al. 2008)

c

The evolution of VLA-COSMOS The evolution of VLA-COSMOS (weak) radio AGN(weak) radio AGN

Smolčić et al. (ApJ, sub.)

Volume averaged mechanical heating rate

Comoving BH accretion rate density

20cm lumiosity functions for VLA-COSMOS AGN (red)

Ledlow & Owen (1996) FRI / FRII diagnostic plot for VLA-COSMOS AGN

Qualitative agreement between cosmological model and observations is very encouraging for the idea of ‘radio mode’ feedback

Summary & EVLA outlookSummary & EVLA outlookVLA-COSMOS: Composition of sub-mJy radio population: fair mix of SF and low-power AGN galaxies z ≤1.3:

Cosmic evolution of VLA-COSMOS SF and AGN galaxies First observational insight into ‘radio mode’ feedback beyond the local universe

z ~ 3: stacking down to 1μJy levels that EVLA will be able to observe

EVLA-COSMOS: Deeper 20 cm imaging:

probing radio LIRGs (>10 MSUN/yr) through cosmic time complete sample of ULIRGs (>100 MSUN/yr) out to high z probing weak radio AGN out to high z testing cosmological models

6 cm imaging: high resolution: radio morphology, composite objects spectral indices probing thermal (free-free) radio emission for z>3.5

VLA-COSMOS Large Project limits