Millimeter detection of Spitzer selectedhyperluminous infrared starburst galaxies

Alain Omont (IAP)

The SWIRE Spitzer survey has detected by far the largest set of Sub-Millimeter Galaxies (SMG)

But their identification is difficult and requires validation with (sub-)millimeter observations

With MAMBO/IRAM we detected at 1.2mm 20 SWIRE z~2 starburst HLIRGs with LFIR~1013Lo They belong to a rather rare subclass of SMGs, with large PAH/FIR ratio and large stellar mass

OUTLINE

• General goals

• Background: High z submillimeter galaxies (SMGs)

• Summary of millimeter dust detection in SMG hosts of high z QSOs

• Identification of hyperluminous SMGs in SWIRE Spitzer survey The SWIRE survey Detection of SMGs in SWIRE 1.2mm Mambo observations of SWIRE HLIRGs Properties of starburst SWIRE HLIGRs a subclass of SMGs rich in PAH and stars Search for AGN SWIRE HLIGRs

Prospects

• Other projects in progress with CFHTLS & Spitzer data and IRAM observations

Millimeter detection of Spitzer selected hyperluminous infrared starburst galaxies

z Dphot (Gpc)

1000

--------------------

20 230

12 130

--------------------

z= 6 60

--------------------

z=2 16 -------------------

0.5 3--------------------

0

~ 300 million

~ 3.5 billion

z ~ 7 – 20 ?- Reionization PopIII stars +1st galaxies-Formation of 1st galaxies Pop. II stars - First AGN

z ~ 4 – 7 :Current frontier- Galaxy and Black-Hole early assembly- End of reionization

z ~ 1.5 -4: - Peak of star formationsubmm sources + LBGs-Peak of QSO activity

z ~ 0.5-1.5 : Final phase of active SF - Weak X-ray AGN- Cluster formation

Main z ranges in the Cosmic History of galaxies

High-z Galaxies, Star Formation and AGN

• Much progress in the last 5-10 years about the exploration of the high-z Universe

High-z galaxies: HDF, Lyman-Break Galaxies, Lyman- Galaxies, etc.z ~ 2 – 3 6 – 7

High-z QSOs and radiogalaxies: peak at z ~2 – 3 6.4

SCUBA/MAMBO submillimeter galaxies (SMGs): peak at z ~2 – 3

• Good view of history of star formation in the Universe:

- First starbursts at z > 7

-Early star formation in early type (elliptical) galaxies major mergers/starbursts

- Late type (spiral) galaxies formed most of their stars at z < 1

• Strong connection between AGN black-hole growth and galaxies (bulge/spheroid) and their starbursts

SMGs: strongest starbursts in the UniverseImportant players of star formation at z >~ 2

Giant starbursts at the peak of elliptical formation z ~ 2-3 1-4

Most of the energy in the far-infrared (FIR) dust at ~40K

At least Ultra-Luminous Infra-Red Galaxies (ULIRGs: Sanders & Mirabel 1996):

• LFIR >~ 1012 Lo, star formation rate SFR > 100 Mo/yr

• Relatively rare, but ~1 per arcmin2

• Generally not isolated; strongly biased along high-z Large Scale Structures

• Probably progenitors of massive elliptical galaxies

• A few of these objects are powerful QSOs or radiogalaxies MBH >~ 108 Mo

Spectral Energy Distribution (SED) of ULIRGs/SMGs

Starbursts

AGN AGN+starburst

obs=rest(1+z)

PAH

SiO

FIR1.2mm obs

SMGs: strongest starbursts in the Universe

Giant starbursts at the peak of elliptical formation z ~ 2-3 1-4

At least Ultra-Luminous Infra-Red Galaxies (ULIRGs):

• LFIR >~ 1012 Lo, SFR > 100 Mo/yr

• Relatively rare, but ~1 per arcmin2

• Generally not isolated; strongly biased along high-z Large Scale Structures

• Probably progenitors of massive elliptical galaxies

• A few of these objects are powerful QSOs or radiogalaxies MBH >~ 108 Mo

Most exceptional Hyper-Luminous IR Galaxies (HLIRGs):

• LFIR >~ 1013 Lo, SFR ~ 1000 Mo/yr

• Nothing equivalent in the local Universe

• Very rare ~1 per 50-100 arcmin2

• CO already detectable

• Probably in most massive DM halos progenitors of central cD galaxies of clusters

• A fraction of them are very powerful QSOs or radiogalaxies MBH >~ 108 Mo

from Bertoldi, Voss, WalterLFIR = 4x1012 S250(mJy) Lsun

FIR emission of cold dust (Td ~ 35-50 K) :

- steep submm spectrum - compensates for distance - S practically independent of z from z ~ 0.5 to 10

Effect also known as « negative K correction »

Redshift degeneracy

Dust detection: The Magic of the high-z submm window

SCUBA (+MAMBO) submm counts SCUBA(-radio) redshift distributionChapman, Blain, Smail, Ivison 2005

SCUBA(-MAMBO) census of high-z ULIRGs

• Take advantage of steep submm spectrum• Account for good part (most) of submm background• z at Keck for radio ones (~50%) (weak AGN ?) History of star formation up to z~3-4• Small but uncertain number at z > 4

Dust detection: the magic of the submm window

Submm counts

from the SHADES survey

Coppin et al. 2006

High-z millimeter studies at IRAM

1. MAMBO detection of redshifted far-IR/submm dust emission from high-z QSOs

A. BeelenF. BertoldiC. CarilliP. Cox+ J. Bergeron, K. Isaak, R. McMahon, R. Priddey, etc+ X.H. Fan, M. Strauss, Ran Wang, etc.

( 2. CO detections with the Plateau de Bure Interferometer )

Omont et al. 1996Carilli et al. 2001Omont et al 2001Omont et al 2003Bertoldi etal. 2003Beelen et al. 2007Wang et al. 2007

MAMBO/IRAM detection of redshifted far-IR/submm dust (and CO) emission from high-z QSOs

• To establish correlations between major starbursts and black-holes at high z

• It is the easiest way to find (biased) cases of HLIRGs at very high z, since the redshifts of SCUBA/MAMBOsources are practically unknown at z > 4 • IRAM 30m Telescope ( Spain) + MAMBO bolometer cameras (Bonn)

• 200 bright QSOs Lbol ~ 1013 -1014 Lo with z~2-6 : 55 detections

• LFIR ~ 1013 Lo HLIRGs

SFR ~ 1000 Mo/yr (if pure starburst)

• Concommittant major starbursts

and AGN. But the far-IR luminosity is

weakly correlated with Lbol

• CO has been detected in 18 high-z QSOs

with the IRAM interferometer

Millimeter detection of Spitzer selected hyperluminous infrared starburst galaxies

• The SWIRE survey

• Detection of SMGs in SWIRE and identification strategy

• 1.2mm Mambo observations of SWIRE HLIRGS

• Properties of starburst SWIRE HLIGRS a subclass of SMGs rich in PAH and stars

• Prospects

Main collaborators: Carol Lonsdale, Mari Polletta (UCSD)+ D. Farrah, D. Shupe, R. Zylka, S. Berta, B. Siana, N. Bavouzet, G.Lagache, H. E. Smith, F. Bertoldi., P. Cox, C. De Breuck, H. Dole, D. Lutz, L. Tacconi,I. Perez-Fournon, H. Aussel, H. McCracken, D. Clements, M. Rowan-

Robinson A. Franceschini, D. Frayer

High-z millimeter studies at IRAM. 3.

Importance of extensive studies of larger samples of high-z SMGs

• Major starbursts of massive (elliptical) galaxies: initial collapse or major mergers

• Parallel growth of super-massive black holes

• Trace density peaks, first massive dark matter halos and early Large Scale Structures

Importance of larger samples of high-z SMGs• Various statistical studies

• Trace their spatial distribution along early LSS

• Identify the rare most extraordinary, mm-brightest ones strong lensed cases or most luminous (far-IR) galaxies LFIR > 1013 Lo, HLIRGs

Present SMG samples are very limited

Only ~400 sources provided by SCUBA/MAMBO surveys( <~ 0.5 deg2)

Waiting for very large samples/areas (~>2007) of SCUBA2 (850µm),

ASTRO-F/AKARI (50-200 µm) and (~>2008) Herschel (100-500 µm)

Much larger (x~20-50) samples already exist (buried) in Spitzer wide field surveysin particular SWIRE: 50 deg2, 10000 - 15 000 SMG

Spitzer provides the first wide field (mid-)IR surveys

Spitzer is:

• Very well matched to the detection of red galaxies (elliptical, LIRGs…) up to z~1

• As well as AGN (Type 1 and 2 QSOs, etc.) up to z~3

• Even pretty sensitive for high-z SMGs although most energy is in FIR outside of Spitzer sensitiverange

Wide-field Spitzer surveys (FLS, GTO, SWIRE) cover in total about 70 deg2:

SWIRE Legacy Project: 50 deg2 (PI Carol Lonsdale)µm 3.5 4.5 5.8 8.0 24

µJy 3.7 4.5 48 38 106 nominal limits Lonsdale et al. 2004:

10 10 45 50 250 present catalogs

( ? ~100 mJy at 160 µm, ~20 mJy at 70 µm)

Identification of SMGs in SWIRE

Direct Spitzer detections of ~90 known SCUBA/MAMBO SMGs at z~2

with SWIRE sensitivities, HLIRGs with S(850µm) > 7 mJy or S(1.2mm) > 2.5 mJy:are detected at >90% at 3.8 and 4.5 µmand at ~45% in most IRAC (3-8µm) bands and MIPS 24µm

150-300 per deg² (0.05-0.1 per arcmin2)

0.7-1.5 104 in total SWIRE

~20-40 times more than all existing MAMBO-SCUBA surveys

HLIRGs

Strategy for Identification of SMGs in SWIRE

• Careful identification criteria of HLIRG candidates from SWIRE+ optical data + SMG SED templates

• Difficult extrapolation from 24µm to 1.2mm (need to simultaneously determine the SED and redshift from five SWIRE bands (3.6-24µm)

Spectral Energy Distribution (SED) of ULIRGs/SMGs

Starbursts

AGN AGN+starburst

SC

UB

A-M

AM

BO

SW

IRE

Spitzer infrared SED of detected with SCUBA or MAMBO

Strategy for Identification of SMGs in SWIRE

Four successive MAMBO projects scheduled at IRAM-30m (Fall 2005 – Winter 2007) for detecting SWIRE HLIRGs candidates at 1.2mm (S1.2mm >~2-5 mJy):

- 2005-2006: 24µm-bright starburst best candidates: 20 detections

- November 2006: AGN best candidates

- Winter 2007: 24µm-bright starbursts, unbiased sample

• Careful identification criteria of HLIRG candidates from SWIRE+ optical data + SMG SED templates

• Difficult extrapolation from 24µm to 1.2mm (need to simultaneously determine the SED and redshift from five SWIRE bands (3.6-24µm)

1.2mm observations of 24µm-bright starburst SWIRE HLIRGS

Observation of a sample of ~60 best candidates with:

- starburst-dominated SED

- S(24µm) >~ 400 µJy

- maximum in 5.8 µm IRAC band (redshifted 1.6 µm stellar bump z ~ 2)

1.2mm observations of 24µm-bright starburst SWIRE HLIRGS

Observation of a sample of ~60 best candidates with: - pure starburst SED - S(24µm) >~ 400 µJy - maximum in 5.8 µm IRAC band (redshifted 1.6µm stellar bump z ~ 2)

One third are detected with S(1.2mm) >~ 2 mJy

Average value < S(1.2mm) > = 1.6 mJy

Majority of the sources are ~HLIRGs with LFIR close to 1013 Lo

Follow-up at 350µm at CSO in January 2007 Tdust , accurate LFIR

Properties of 24µm-bright starburst SWIRE HLIRGS

Mid-IR spectra obtained with Spitzer IRS for 5 sources detected at 1.2mm

practically pure PAH spectra

confirmation of redshift ~ 2 (1.7 – 1.9)

Observed spectrum

Properties of 24µm-bright starburst SWIRE HLIRGS

Mid-IR spectra obtained with Spitzer IRS for 5 sources detected at 1.2mm

practically pure PAH spectra

confirmation of redshift ~ 2 (1.7 – 1.9)

Average spectrum

9 starburst sources

Weedman et al. 2006

Properties of 24µm-bright starburst SWIRE HLIRGS

Redshifts in the range 1.7 – 2.5 ( z-spectro 1.7 – 1.9 )

Ratio S(1.2mm)/S(24µm) much smaller than most SMGs whose typical SEDis relatively cold, similar to Arp 220

Their SED is rather similar to M82 or NGC6090

Properties of 24µm-bright starburst SWIRE HLIRGS1. Large ratio PAH/FIR emission

Ratio S(1.2mm)/S(24µm) much smaller than most SMGs whose typical SEDis relatively cold, similar to Arp 220

Their SED is rather similar to M 82 or NGC 6090

Strong ratio of PAH/FIR emission

Maybe they are more extended starbursts less opacity and less absorption of PAH emission

With perhaps strong superwind as inM82 ?But scaled by a factor > 10 enrichment of intergalactic medium in heavy elements??

Extended PAH emission in the super wind of M82Engelbracht et al. 2006

Properties of 24µm-bright starburst SWIRE HLIRGS2. Large stellar masses

Masses in red stars range from 8x1010 to 6x1011 Mo, if the mean stellar age is below 109 years, and significantly higher masses if the stars are older.

They are probably young massive ellipticals in the final stages of star formation, where much of their stellar mass is already in place, yet very high rates of star formation are still proceeding.

The rare starburst episode is likely to be very short lived, to avoid that the total accumulated stellar mass by the end of the burst exceed that observed in the largest local ellipticals.

Probably one of the latest gas-rich major mergers of a massive elliptical

MAMBO observations of SWIRE HLIRG AGN candidates

October-November 2006: bad weather; 1/3 of proposal observedXMM-LSS and Lockman SWIRE fields

• 14 Sources fitted with composite starburst-AGN SEDs- average flux: 1.53 +/-0.40 mJy- the majority should be HLIRGs

• 11 sources with « Torus » featureless SEDs- average flux: 0.46 +/-0.38 mJy- few HLIRGs

Spectral Energy Distribution (SED) of ULIRGs/SMGs

Starbursts

AGN AGN+starburst

MAMBO observations of SWIRE HLIRG AGN candidates

October-November 2006: bad weather; 1/3 of proposal observedXMM-LSS and Lockman SWIRE fields

• 14 Sources fitted with composite starburst-AGN SEDs- average flux: 1.53 +/-0.40 mJy- the majority should be HLIRGs

• 11 sources with « Torus » featureless SEDs- average flux: 0.46 +/-0.38 mJy- few HLIRGs

• Confirmed detection of two exceptional sources - u-dropouts in D1 CFHTLS Deep Field: z ~3 – 4- probably red QSOs- S24µm ~ 2–3 mJy- S1.2mm ~ 5 mJy- Nature of IR emission still unknown

Band u g r i z 3.6 4.5 5.8 8.0 24um 1.2mm 20cm------------------------------------------------------------------------------------------------------------------------SW49208 z ~ 3 – 3.5

m_AB <26 24.6 23.4 23.0 22.5 20.9 20.7

Flux(µJy) 3.6 15.8 19.7 <50 185 2406 ~5000 350------------------------------------------------------------------------------------------------------------------------SW55275 z ~ 3.5 - 4

m_AB 25.5 23.0 21.7 22.0 22.4 20.9 20.5

Flux(µJy) 4.0 15.5 23.0 <50 245 3271 ~5000 140

------------------------------------------------------------------------------------

Confirmed detection of two exceptional sources

- u-dropouts in D1 CFHTLS Deep Field: z ~3 – 4 (to be confirmed)- probably red QSOs- S24µm ~ 2–3 mJy- S1.2mm ~ 5 mJy- Nature of IR emission still unknown- Very large ratios 24/8.0µm and 8.0/5.8µm

PROSPECTS

(2005-2006: 24µm-bright starbursts, best candidates: 20 detections November 2006: AGN best candidates)

- Winter 2007: 24µm-bright starbursts, unbiased sample

Goal to characterize this subclass of strong starbursts with 5.8µm bump and S(24µm) > 400µJy (50 per sq. deg.) and its average star formation rate.

Previous samples were biased towards the identification of the most luminous objects, so that the average starburst properties of the bulk of this class remain undetermined.

We have been awarded 39h of MAMBO observations to observe an unbiased complete random sample, which has excellent X-ray and optical coverage, to determine the average value of S(1.2mm) and inferred quantities

PROSPECTS• (New 1.2mm Mambo observations: - Winter 2007: 24µm-bright starbursts, unbiased sample)

• Follow-up at 350µm at CSO in January 2007 Tdust , accurate LFIR

• Observations in SWIRE southern fields with APEX/LABOCA

• CO search with IRAM interferometer when accurate redshifts

• Morphology studies: - HST? - Look for relatively nearby similar objects; at least ULIRGs

• Full identification of SWIRE z~2 HLIRGs (+ ULIRGs) warranted with Scuba 2 (2007) and Herschel (2008)

• Detailed studies with ALMA (2012)

Other projects in progress with CFHTLS & Spitzer data and IRAM observations

• Identification of Type 1 and 2 QSOs in CFHTLS/Spitzer fieldsPei Yu, J. Bergeron, X. Liu; N. Bavouzet

• 1.2mm MAMBO maps of deep Spitzer + multi- fieldsA. Baker, C. Lonsdale, F. Owen; F. Bertoldi

• 1.2mm observations of high z QSOs and IRS Spitzer sourcesM. Jarvis; C. Willott; Ran Wang; D. Lutz, L. Yan

• CO observations of high z sourcesI. Smail, P. Cox; D. Lutz, L. Yan; Ran Wang; F. Bertoldi; R. Genzel

Plateau de Bure IRAM interferometer

CO detection in 18 high-z QSOs

Dense gasdensity ~105 cm-3

T ~ 100 Ksize R ~400-1400 pcgaz mass 1-2 1010 Mo

CO detection in QSO SDSS J1148 at z=6.42

Bertoldi et al. 03 PdBI

Walter et al. 03 VLA

Multi-line excitation model

Resolution of CO in 2 sources VLA Walter et al. 04

CO detection in18 high-z QSOs

SCUBA (+MAMBO) submm counts SCUBA(-radio) redshift distributionChapman, Blain, Ivison, Smail 2003

SCUBA(-MAMBO) census of high-z ULIRGs

• Take advantage of steep submm spectrum• Account for good part (most) of submm background• z at Keck for radio ones (~50%) (weak AGN ?) History of star formation up to z~3-4• Small but uncertain number at z > 4

Dust detection: the magic of the submm window