Ultra-Luminous Infrared Galaxiesat high redshift - The Spitzer

perspective

E. Le Floc’h (Steward Observatory, University of Arizona)

* Spitzer-NDWFS : A.Dey, K.Brand, B.Jannuzi (NOAO), V.Desai, T.Soifer, L.Armus, C.Borys (Caltech), S.Higdon, J.Higdon, D.Weedman (Cornell), K.Tyler (Arizona)

* MIPS team : C.Papovich, G.Rieke (Arizona), H.Dole (IAS-Orsay)

Galaxies and Structures through Cosmic Times, March 29th, 2006

•* DEEP : C.Willmer, K.Noeske, D.Koo, E.Laird, P.Nandra, N.Konidaris,• J.Lotz, A.Coil, C.Conselice, P.Barmby, M.Ashby, R.Ivison, …

+ R.Gilli, R.Maiolino, E.Bell, V.Charmandaris, D.Elbaz, ….

IRAS and the ULIRGs at low redshift

( Mirabel et al. 1991)

InfraredUV

(visible)

.

(Sanders & Mirabel 1996)

(Sanders & Mirabel 1996)

(Adapt. Devriendt et al. 1999)

ULIRGs:

- L(8-1000 m) > 1012 L

- only a few % of the IR energy density in the local Universe

Galaxies and Structures through Cosmic Times, March 29th, 2006

ULIRGs

Spirals

Infrared luminosity functions

Local IRAS LF

Galaxies and Structures through Cosmic Times, March 29th, 2006

Faint-end slope constrained from the deep source counts in GOODS-N as well as stacking analysis with COMBO-17 (Zheng et al. 2005)

1000x !

< 10

LF05

ULIRG evolution with redshift

1<z<3

Galaxies and Structures through Cosmic Times, March 29th, 2006

LF05

?( © Hughes et al.)

SCUBA

Spitzer ULIRGs at z>1

- «template» selection : e.g., Le Floc’h et al. 04, Lonsdale et al. 04, Rowan-Robinson et al. 05

- LBGs : e.g., Huang et al. 05

- DRGs : e.g., Papovich et al. 06

- BzKs : e.g., Daddi et al. 05 (also X.Kong’s talk)

ULIRGs

… no single approach with a uniform selection. Which connection between these populations ?

(Papovich et al. 2006)

Galaxies and Structures through Cosmic Times, March 29th, 2006

DRGs

Galaxies and Structures through Cosmic Times, March 29th, 2006

R-24 selection of z>2 ULIRGs

Bootes

CDFS

> 0.3 mJy

> 0.08 mJy

- F24m > ~1mJy- R > ~24-25 mag

(extreme IR/opt ratios)

IRS spectra : 2<z<3

coeval to the SCUBA sources

but 5-10x brighter in the mid-IR

(Houck et al. 2005, Yan et al. 2005, Weedman et al. 2006)

(deep)

(shallow)

R - 24m > 15

Galaxies and Structures through Cosmic Times, March 29th, 2006

AGNs or starbursts ?

Starburst

4 6 8 10 12 14 16

- also lots of feature-less power-laws (no redshift)

- in most cases : features from Si

- rarer but still detected : PAHs

Bias toward AGNs / warm sources

(Brand et al. 2006)

Starbursts

* AGNs* X-ray sources* > 1mJy pop.

Wavelength (micron)

AGN

Galaxies and Structures through Cosmic Times, March 29th, 2006

AGNs or starbursts ?

ColdWarm

(Chapman et al. 2005)

MIPS SCUBA

(2004)

Galaxies and Structures through Cosmic Times, March 29th, 2006

Far-IR properties of z>2 ULIRGs

- 70m and 160m stacking at the

positions of the 24m-selected ULIRGs (K.Tyler et al.)

- Spitzer GO2 : deep imaging at

70m and 160m

70m24m 160m

Z=2.46

(Borys et al. 06, Desai et al. 06)

Starburst-dominated HyLIRG

Z=1.3

CXO-J141741.9+522823

, LX ~ 2x1044 erg/s- NH ~ 1022 cm-2

- 6 mJy @ 24 m

z = 1.15

Galaxies and Structures through Cosmic Times, March 29th, 2006

- mid-IR spectrum : no Si absorption, very weak PAHs, …

(Page et al. 01, Alexander et al. 05…)

Coeval growth buldge / SM-BH

Galaxies and Structures through Cosmic Times, March 29th, 2006

- Lbol ~ 9x1012 L

- 50% cold, 50% warm, …

- 20% emitted

below 8m

Esbt ~ EAGN

CXO-J141741.9+522823

H He ~ 0.7%Acc. ~ 10%

-

-

Esbt ~ 5 x EAGN to satisfy theMagorrian relation *if* Tsbt = TAGN

Galaxies and Structures through Cosmic Times, March 29th, 2006

Summary

* ULIRGs at 0<z<1 : increasing contribution to the IR energy density, reaching ~10% at z~1* ULIRGs at z>1 : not a uniform selection yet

* Connection between SCUBA- and optical/near-IR selections still to be addressed

* A « new » population selected with extreme IR/opt. ratios and located at 2<z<3

- AGN-dominated in the mid-IR, but evidence for starburst emission in the FIR•- Might witness the coeval growth of stellar buldges• and SM black holes, but with different time scales