ULTRALUMINOUS INFRARED GALAXIES: 2D KINEMATICS AND STAR FORMATION

L. COLINA, IEM/CSIC

S. ARRIBAS, STSCI & CSIC

D. CLEMENTS, IMPERIAL COLLEGEA. MONREAL, IACM. GARCIA-MARIN, IEM/CSIC

• SAMPLE OF LOW-Z ULIRGs AND INSTRUMENTATION

• ARP 220: STRUCTURE OF THE EXTENDED WARM IONIZED GAS

• 2D KINEMATICAL PROPERTIES OF ULIRGS

• DYNAMICAL MASS TRACERS

• IMPLICATIONS FOR HIGH-Z GALAXIES: SFR AND MASS

• CONCLUSIONS

OUTLINE

SAMPLE OF LOW-Z ULIRGS

REDSHIFT LUMINOSITY ACTIVITY MERGING PHASEZ < 0.2 11.8 < log(LIR/L) < 12.6 HII - Sy1 EARLY/LATE

INTEGRAL on WHT

3 fiber bundles:

2.7033.6x29.4SB3

0.9016.0x12.3SB2

0.457.80x6.40SB1

Ø (”)FoV (”x”)Mode

Arribas et al. 1998

INTEGRAL FIELD SPECTROSCOPY OF ULIRGS

ARP 220: INTEGRAL FIELD SPECTROSCOPY (I)*

* Colina, Arribas & Clements, 2004, ApJ 602

28 X 15 Kpc

SB3 BUNDLE

15000 s

6000 s 18000 s

ARP 220: INTEGRAL FIELD SPECTROSCOPY (II)

Log F(H) > -17 erg cm-2 s-1 arcec-2

350 spectra4500 - 7500 A

ARP 220: HST vs IFS STELLAR STRUCTURE

WFPC2 F814W

INTEGRAL SB3

*

ARP 220: 2D IONIZED GAS STRUCTURE

W LOBEE LOBE

NW PLUME

SE PLUME

ARP 220: ORIGIN OF EXTENDED IONIZED GAS*

3 6.2 2.7 10.49NGC 3079

1.3 1.5 0.37 10.46NGC 253

24 0.3 0.16 12.16Arp 220 Lobes

7 0.6 0.14 12.16Arp 220 Plumes

Extent (kpc)

LX/LIR

(xE-5)

LH /LIR

(xE-5)

log LIR

(L)

Galaxy

* Colina, Arribas, Clements 2004, ApJ 602

M82 10.52 16 2.6 2.4

Distance (Mpc)

77.6

77.6

3.0

3.0

16

STARBURST-INDUCED SUPERWINDS OR MERGER-INDUCED SHOCKS

ARP 220: ORIGIN OF EXTENDED IONIZED GAS

McDowell et al. 2003, ApJ 591

MERGER-INDUCED STRUCTURES?SIMULATION (S. LAMB)

- Gas-rich galaxies

- Comparable-mass

- Low impact velocity

- Face-on collision

ARP 220: VELOCITY vs STELLAR AND GAS STRUCTURES

STELLAR STRUCTURE

GAS STRUCTURE

STELLAR STRUCTURE

- Peak-to-peak V of 600 km/s

- Vel. Deviations of 300 km/s

- Vel gradients of 50 km/s/kpc

- Associated with the stellar envelope

- Average velocities of E and W lobes: +8 and -79 km/s

- Not dominated by central, starburst-driven wind

- Average velocities of E and W lobes consistent with merger simulations (to first order)

2D KINEMATICAL PROPERTIES OF ULIRGS (I)

HST F160W CONT. H VELOCITY DISP. VELOCITY FIELD

2D KINEMATICAL PROPERTIES OF ULIRGS (II)

HST F160W CONT. H VELOCITY DISP. VELOCITY FIELD

Velocity field on scales of few to several kpc does not correspond in general to that of an ordered, rotating system

Peak-to-peak velocity amplitudes of up to 600 km/s are detected in tidally induced structures: tails and extranuclear star-forming regions The peak of the velocity dispersion in 60% of the ULIRGs studied does not coincide in position with the stellar nucleus

Velocity dispersions associated with extranuclear, diffuse ionized gas are large: 150 to 250 km/s

Velocity dispersion associated with the less massive, secondary nucleus in pairs is not distinguishable from that of the extended, diffuse gas

Extended ionized gas velocities on scales of few to several kpc are not wind-related but merger-induced

2D KINEMATICS OF ULIRGS: SUMMARY

MASS TRACER: CENTRAL VELOCITY AMPLITUDE

: cold gas: stars

IF ROTATION: MASS V2 R HOWEVER

VELOCITY AMPLITUDE DOES NOT TRACE ROTATION, IN GENERAL

VELOCITY AMPLITUDE IS NOT A RELIABLE TRACER OF DYNAMICAL MASS

MASS TRACER: CENTRAL VELOCITY DISPERSION

: stars: cold gas

MASS 2 Re

: Central velocity dispersionRe: Effective radius

VELOCITY DISPERSION IS A RELIABLE TRACER OF DYNAMICAL MASS

ULIRG MASSES

0.1m* < m < 1.1m*

m= 0.4 0.3 m*

m*= 1.4E+11 M

IMPLICATIONS FOR HIGH-Z GALAXIES: SFR and MASS

• LIRGS and ULIRGs carry a large fraction oof SF at z> 1

• SPITZER and HERSCHEL most likely to detect LIRGs at high-z

KEY PARAMETERS SFR AND DYNAMICAL MASS H line

Strong differential extinction effects Decoupled ionized & stellar structures INTEGRAL FIELD SPECTROSCOPYComplex 2D velocity field

• H line shifts into the near and mir-IR (1 to 10 micron) for z> 1

• near-IR multi-slit spectrographs NOT GOOD ENOUGH

MISLEADING DERIVATIONS OF SFRs AND MASSES IN HIGH-Z LUMINOUS DUST-ENSHROUDED STARBURST

IMPLICCATIONS FOR HIGH-Z GALAXIES (I)

García-Marín, Colina & Arribas, see poster

Av (C)= 5.6 magAv (D)= 2.2 mag

IMPLICATIONS FOR HIGH-Z GALAXIES (II)

García-Marín, Colina & Arribas, see poster

HST F814WNIRCam Z=2.5

INTEGRAL H

NIRSpecIFU H

SFR(1)/SFR(2)= 2 m(1)/m(2)=0.25

1

2

IMPLICATIONS FOR HIGH-Z GALAXIES: SUMMARY

IF most high-z galaxies are merging systems such as low-z ULIRGs THEN

H velocity amplitudes should not be used in general to estimate Mdyn

H central velocity dispersions are a more reliable tracer of the Mdyn, provided the true nucleus is known from near-IR imaging

H-based star formation rates can be underestimated, factors 2 or 3 in some systems, even if corrected by strong differential extinction effects

Long-slit spectroscopy could give misleading results. IFS desirable.