Exploring structure around submillimetre-bright QSOs

Francisco J. Carrera (IFCA, CSIC-UC, Spain/Imperial, UK)

Mathew J. Page (MSSL-UCL, UK)Jason Stevens (CAR, U. Hertfordshire, UK)

Rob Ivison (ROE, UK)Serena Falocco (IFCA, CSIC-UC, Spain), Jacobo Ebrero

(SRON, NL) MSSL, 14-July- 2010

Outline

• Introduction: our hard QSO sample– What we now so far about them

• Environment in submm: strong overdensities• Confirmation for RXJ0941

– Radio imaging– SEDs– Presence of AGN– Evolutionary status

• Summary

Introduction: our hard QSO sample(Page+01,04,10 Stevens+04,05)

• Sample of Broad Line QSO with X-ray absorbed spectra– At z and LX where most contribution to X-ray background– Matched sample of similar (LX,z) unabsorbed QSO

• Strong difference in submm fluxes:– Absorbed mostly bright, unabsorbed mostly faint – All submm detected are at z>1.5– Submm much too bright to come from AGN: strong star

formation

• Absorbed BLQSO are ~10-15% of BLQSO population• X-ray-UV spectra: strong ionized winds, enough to

terminate SFSimultaneous strong growth of BH and star formationStronger SF in the pastTransitory phase ~10-15% QSO lifeJust starting to blow away circumnuclear material?

Environment in submm: SCUBA 850m

(Stevens+05,+10)

~40

0kp

c ~2´

• 2-4x overdensities• Structure in 100skpc• Each an ULIRG (if @z)• Some: disturbed

morphol.– Major galaxy merger

These QSOs are sitting in overdensities in the UniverseSubmm luminosity from starburst (triggered by fusion/interaction?)

Confirmation for RXJ0941: radio imaging

• 4 450m sources, 3 850 m sources (2 in common): 5 total• All in radio (plus blob?) (Carrera+10)

i K 4.5m

8m 24m 450m

850m 6cm 20cm

Confirmation for RXJ0941: photo-z

• Radio imaging: submm sources real– pinpoint some counterparts

• Counterparts very faint for spectroscopy • Photometric redshifts (hyperz):

– Fitting spectral templates (MRR08) to RiZJK-4.5,8μm• Also tried Bruzual & Charlot 2003: similar z• Only fit to rest-frame optical-NIR: no dust

– Best if conspicuous feature: Balmer break @3646Å• @z=1.82: between Z and J

– MK: bulge (stellar) mass M* from Borys+05• Also used MRR08 (diff M/L): a factor 2-3 larger

Confirmation for RXJ0941: z and SEDs

• Once z: Spectral Energy Distribution (SED)• Using Chary & Elbaz 2001 templates for

≥MIR– Dust emission– Not expected good match to rest-frame Opt.-NIR

• But surprisingly good…

– Not fit: renormalizing to 450μm, 850μm, 4.5μm,…

• From CE01 templates:– LIR Star Formation Rate (SFR) (Kennicutt 1998)

• From 450μm/850μm fluxes:– Assuming (T/,) (QSO/SMGs Martínez-

Sansigre+09) dust mass

F(

cgs/

Å)

RXJ0941: the QSO

850_1/450_1

i K 4.5m

8m 24m 450m

850m 6cm 20cm

obs(Å)

• z=1.82• Several components:

– AGN direct accretion (MRR+08)

– AGN re-processing: torus (MRR+08)

– Star formation: LIR~2x1013L

• Dominates in MIR/submm

• SFR~4000M/y

850_2/450_2

Phot. z=1.85LIR~2x1013L

SFR~4000M/ylog(M*/M)~11.6

obs(Å)

F(

cgs/

Å)

i K 4.5m

8m 24m 450m

850m 6cm 20cm

Photo-z fitCE01 450μmCE01 850μm

obs(Å)

F(

cgs/

Å)

850_3

Phot. z=1.85LIR~0.5x1013L

SFR~900M/ylog(M*/M)~11.5

i K 4.5m

8m 24m 450m

850m 6cm 20cm

Photo-z fitCE01 4.5μmCE01 850μm

Phot. z=1.85LIR~1013L

SFR~2400M/y log(M*/M)~11.5

obs(Å)

F(

cgs/

Å)

450_4

i K 4.5m

8m 24m 450m

850m 6cm 20cm

Photo-z fitCE01 450μm

Phot. z=2.8LIR~2x1013L

SFR~4000M/y log(M*/M)~11.5

i K 4.5m

8m 24m 450m

850m 6cm 20cm

450_3

obs(Å)

F(

cgs/

Å)

Photo-z fitCE01 4.5m

CE01 450μm

Table summary

Source z LIR

(1013L)

SFR(M/y)

Mdust

(108M)

logM*

(logM)Flux (μJy)

450(850)μm

850_1/450_1 1.82

2.4 4100 5-22 - 4010

850_2/450_2 1.85

2.2 3800 4-23 11.6 4010

850_3 1.85

0.5 900 2-6 11.5 (32)

450_3 2.8 2.1 3600 4-25 11.3 349

450_4 1.85

1.4 2400 3-16 11.5 298• One spurious expected from logN-logS (Coppin+06)

• log(M*/M)~11.50.2 (inc. z and K)• SFR~2000 M/y• Mdust~109M (interval from z, T/, )

– Mgas~5×1010M (Kovács+06 SMG, Seaquist+04 SCUBA)

Presence of AGN

• X-ray upper limits on soft (6×10-16cgs) and hard (4×10-15cgs) bands:– Using Gilli+07 models– 2-10keV luminosity upper

limits

• All 24μm from AGN: very conservative (Elvis+94)

log(LX/cgs)<44• BC~35

(Marconi+04,Elvis+94) ~0.2 (SMGs z~2 low LX

Alexander+08) log(MBH/M)<8.1 ( +log(BC/35)-log(/0.2) )

soft

hard

Evolutionary state(Borys+05, Alexander+08, Michalowski+10…)

• log(M*/M)~11.50.2 (~other SMG samples): – ~Schechter mass of MIR-sel gals. (Pérez-González+08)– Gas mass ~10% galaxy mass

Galaxy mature and not much further growth

• log(MBH/M)<8.1 (7.4-8.4 with BC, )

• (MBH/M*)/(MBH/M*)local< 6 (1-100 with ) (Marconi&Hunt

04)

– ~1 only if flux at X-ray upper limit and NH>>

– LX~5×1043 erg/s (SMG Alexander+08), M*×2 if MRR08…

Growth of BH lags the growth of the galaxy

Evolutionary state

• Plenty of fuel for AGN growth:- Only ~1.5% of Mgas into BH to reach local MBH-M*

• If BH in exponential growth phase:- Mass e-folding time: t=4.4×108y × /(1-)

(Martínez-Sansigre & Taylor 09, Rees 84) =0.2 (low LX SMG Alexander+08)

=0.08 (Marconi+04, M-S&T 09)

MBH×6 (local): t~340My (over by z~1.65)

Summary

• We confirmed overdensity around RXJ0941• Counterparts to 4/5 sources at same z

– Expected ~1 spurious from submm source counts– HLIRGs, SFR~2000 M/y

• Counterparts are massive submm galaxies:– Limited additional growth Already mature

• Any AGN must have log(MBH/M)<8.1– Below local MBH/M* relationship Growth of BH lags growth of galaxy

• Growth of AGN feasible:– Enough fuel– Relatively quickly

• Need: Herschel to measure submm SED shape (good T/, Mdust…), deeper X-ray to measure MBH, photo-z for the rest…

And there are more...

• Photo-z successful for 225– Peak ~1.5-2– Similar for BC03

• 89 sources “close” to z=1.82 within 99% with 3 points

• M* histogram for those 89:– Broad– Narrower if only M*<1: 8-11– All three counterparts in

highest bins

Interpretation: an evolutionary sequence?

• More massive DM halos collapse earlier • Collisions and mergers occur• These processes channel material to the center which

– Makes stars– Feeds the BH

• Material obscures opt/UV (dust) and X-ray (gas)• Heated dust emits FIR which escape unimpeded

Joint spheroid/QSO evolution within a hierarchical clustering scenario (Granato+04, Silk & Rees 1998, Fabian’99, Di Matteo+05)

FIR

X-ray

Interpretation: an evolutionary sequence?

FIR

X-ray

FIR

X-ray

• FIR emission increases ULIRGs• Bulk of submm gal. population

discovered by SCUBA (Smail+97) ?• As BH grows it reaches Sy-like X-ray

luminosities• Absorbed X-ray sources (Alexander+05)

• Signatures of buried AGN in opt spec. (Chapman+04)

Joint spheroid/QSO evolution within a hierarchical clustering scenario (Granato+04, Silk & Rees 1998, Fabian’99, Di Matteo+05)

• Still forming stars (FIR>>)• BH allmost fully grown: QSO

luminosities• QSO radiation and starbursts are

starting to sweep out circumnuclear material:• Less absorbed X-ray sources

our X-ray absorbed QSOs

• BALQSOs in slightly later stage? (Fabian’99)

Interpretation: an evolutionary sequence?

FIR

X-ray

FIR

X-ray

FIR

X-ray

our X-ray absorbed QSOs

Joint spheroid/QSO evolution within a hierarchical clustering scenario (Granato+04, Silk & Rees 1998, Fabian’99, Di Matteo+05)

Interpretation: an evolutionary sequence?

FIR

X-ray

FIR

X-ray

FIR

X-rayX-ray

• Fully grown QSO “living off the rents” our X-ray unabsorbed QSOs

• Passively evolving stellar population

our X-ray unabsorbed QSOs

Joint spheroid/QSO evolution within a hierarchical clustering scenario (Granato+04, Silk & Rees 1998, Fabian’99, Di Matteo+05)