D. B. Sanders Institute for Astronomy,

University of Hawaii

Gas-Rich Mergers and the origin of nuclear starbursts and AGN

The Dusty and Molecular Universe: A prelude to HERSCHEL and ALMA, 27-29 Oct, 2004, Paris

Starbursts and ULIRGs

• IR Galaxies: SEDs, LF (vs.z)

• Origin & Evolution of LIGs/ULIGs• ULIGs: Superstarbursts and AGN• ULIGs and QSOs

OUTLINE

IRAS - ISO - SCUBA - MAMBO(1984) (1996) (1997) (1999) z <0.3 z < 1.5 z < 5-6 ?

SIRTF+AstroF - Herschel - ALMA (2003) (2006) (2008) (2010) z = 0-10?

Two IRAS All-Sky Surveys:

IRAS Revised Bright Galaxy Sample (RBGS:S60>5.24Jy)

638 Galaxies

IRAS 1-Jy ULIG Sample (1-Jy: S60>1.0Jy,Lir > 1012 Lsun)

118 Galaxies

Radio-to-UV SEDs of IRAS Selected Galaxies

“Infrared Galaxies” (f)IR / (f)opt > 1

638 Galaxies: f((60m) > 5 Jy118 ULIGs: f((60m) > 1 Jy

Galaxy Luminosity Functions

LFIR high luminosity tail:

L-2.35

(z) (1+z)5-8 3.5

(z <0.2) ~ 0.008 deg-2

slope = -1

The Hubble Deep Field (The opt/UV view)

SCUBA 850m

The FIR/submm view

kindly provided by Helmut Dannerbauer

ULIGs @ z ~ 2 – 4

f850 ~ 1 – 10 mJy

m K ~ 20 – 24 m I ~ 24 – 30 m B ~ 26 – 33

ULIGs at High Redshift

Galaxy Luminosity Functions

Z=0.40

Z=0.80

Z=0.13

Z=0.045

Z ~2.4

slope= -1

The “Star Formation Rate” versus Redshift

Luminous Infrared Galaxies

The Origin and Evolution of

Strong Interactions/Mergers of Molecular Gas-rich Disks

IRAS RBGS Optical Images of LIGs

Log LIR = 11.66 - 11.99

Ishida, ApJL (2003)

Log LIR = 11.10 - 11.48

IRAS RBGS Optical Images of LIGs

Ishida, ApJL (2003)

Log LIR = 11.49 - 11.99

IRAS RBGS

Conclusion:

In the range log(Lir/Lo) = 11.6 - 12.0, LIGs are in the final stages of merging, with a typical “pre-merger” time of tm < 3 x 108 years

IRAS RBGS Optical Images

Log LIR = 12.00 - 12.51Ishida, ApJL (2003)

IRAS RBGS

Nuclear Separation vs. Lir

IRAS RBGS

Conclusion:

At log(Lir/Lo) > 12.0, > 40% of ULIGs have merged andthe remainder will merge within a time of tm < 108 years

SummaryProperties of IRAS RBGS+1Jy ULIG samples

Log(LIR/Lsun) = 11.40 - 12.70

• Sources are predominantly strongly interacting/merging spiral pairs MK Tot ~ 2 LK*• MK pair ratio < 3:1• LIR pair ratio < 5:1• Pairs are predominantly late type spirals (Sb, Sc)• Both components are molecular gas rich (MH2 ~ 109 - 10 Msun) pair separation as pair LIR

• ( Evidence for buildup of dense nuclear gas concentrations )

• ( Evidence for creation of luminous Seyfert 1 nuclei)

• ( Evidence for S + S E )

LCO

N=53

LHCN

LIR/LHCN

LIR/LCO

LHCN

LCO

Gao et al.Mirabel et al.Hibbard et al.Ponman et al.

Log (LIR/Lsun) = 11.01Int. Class = 3

UGC 83038 = Mrk 231Log (LIR/Lsun) = 12.57Int. Class = 4

Sanders et al.Hutchings & Neff

Scoville et al.Surace et al

SummaryNuclear Molecular Gas Concentrations @ r < 700 pc

General Results for ULIGs

• Mnuc/Mtot = 40 – 100 %

• Mnuc = 1 – 3 x 1010 Msun

(H2) ~ 0.65 – 2 x 1010 Msun

n (H2) spherical ~ 130 – 400 cm-3

• => ffnuc ~ 1 (for a population of W3-like GMCs)

N (H2) spherical ~ 10 23.2 – 23.7 cm-2

OVRO InterferometerBryant, Scoville et al. 1993-9

Summary

Optical Spectral Classification of LIGs+ULIGs

Veilleux, Kim & Sanders (1998) KPNO 4m + UH 2.2m

1-D surface brightness radial profiles

SummaryHost Properties of 1-Jy Sample of ULIGs

Log(LIR/Lsun) > 12.0

• redshift range: 0.018 – 0.271 MK Tot ~ 2.7 LK*

MR Tot ~ 2.5 LR*

• ~ 1/3 are E (r1/4-law profile @ r ~ 1.5 – 6.0 kpc)• ~ 1/3 are E/Sp• ~ 1/3 are “amorphous/chaotic”

Beyond the IRAS RBGS Sample …

Question:

What happens Next ?

A Plausible Scenario …

LIG ULIG QSO

Evolution of Fine Structure in a “post-merger” simulation Barnes (2002)

Evolution of the Luminosity Profile for a “Post-Merger” Remnant Barnes (2002)

R = 27.5 mag arcsec-2

(kpc)

Near-IR Imaging of PGQSOswith Gemini-North Hopuka’a AO System

(Olivier Guyon 2002)

PG 1411+442 40x40 kpc

“Raw Image” (resolution ~0.12 arcsec) PSF-subtracted image ~24 magH arcsec-2 (3)

NIR-AO Imaging of a Complete Sample of 38 PGQSOs Olivier Guyon, PhD Thesis, 2002

Raw (H-band) -psf - <radial profile>

Gemini-N 8m

NIR-AO Imaging of a Complete Sample of 38 PGQSOs Olivier Guyon, PhD Thesis, 2002

Raw (H-band) -psf - <radial profile>

Mean Radio-to-Xray SED of PGQSOs

Warped Disk Model Sanders, Phinney et al. (1989)

• PGQSOs typically have dominant spheroids + a moderate disk component (central bars, mini-spirals, …)

• PGQSO hosts typically have faint tidal debris

“SFR + MBH” versus Redshift

• Good evidence for S + S -> E merger sequence for ULIGs • Good evidence for creation of luminous Seyfert 1 nuclei in ULIGs• Confirmation of strong evolution with z in the ULIG population• ISOPHOT Deep Field sources consistent with LIG/ULIGs (z ≈ 0 -1.5)• ?? SCUBA Deep Field sources consistent with LIG/ULIGs (z ≈2 - 4)??

Summary

•[“SFR” vs. z ]opt+UV [“SFR” vs. z ]IRAS+ISO+SCUBA

•High-z ULIGs may represent epoch of spheroid / MBH formation