An IRAM PdBI CO Survey of Luminous Submm Galaxies A spearhead project for ALMA IDA Meeting,...

An IRAM PdBI CO Survey of Luminous Submm Galaxies

A spearhead project for ALMA

IDA Meeting, Copenhagen 20-21 Dec. 2004

Thomas R. Greve (Caltech)R. Genzel (MPE),R. J. Ivison (ROE),R. Neri (IRAM),I. Smail (Durham),S. Chapman (Caltech),A. W. Blain (Caltech),F. Bertoldi (MPIfR),L. Tacconi (MPE),P. Cox (Orsay),A. Omont (AIP)

Outline A Brief History of CO at high z

Why CO? High-z CO detections to date

An interferometric CO survey of (sub)mm galaxies (SMGs) Duty cycle and current status Bulk gas properties of SMGs Comparison with ULIRGs Implications for galaxy formation models

Conclusions and future directions


High-z CO detections to date


• 13 QSOs, including IRAS F10214+4714 the first ever high-z CO detection (Brown & Vanden Bout 1991)

• 6 High-z Radio Galaxies (HzRGs)

• 1 Lyman Break Galaxy (LBGs)



Omont et al. (1996)

z=4.69






De Breuck et al. (2003)

z=3.52




Omont et al. (1996)

z=4.69



Baker et al. (2003)

z=2.73





z=3.52

Omont et al. (1996)

z=4.69



Omont et al. (1996)


Baker et al. (2003)



• 1 Lyman Break Galaxy

• QSOs+HzRGs show strong CO emission from extended (~10kpc) starburst regions

• Typical gas and dynamical masses of ~1x1011Mo

• Co-eval growth of stellar bulges and massive black holes

• Rapid enrichment before z~7



Omont et al. (1996)


Baker et al. (2003)








However, most high-z CO detections are a mixed bag of non-uniformly selected (and often strongly lensed) QSOs and HzRGs



Omont et al. (1996)


Baker et al. (2003)








However, most high-z CO detections are a mixed bag of non-uniformly selected (and often strongly lensed) QSOs and HzRGs.

SMGs: 2+1 sources detected in CO prior to our survey.

L1L2

R.A. (2000)

Dec

. (20

00)

SMMJ02399-0136 (z=2.81)

velocity offset (km/s)

-1000 -500 0 500

flux density (Jy/beam)

-0.001

0.000

0.001

0.002

0.003

0.004

0.005

1-0.001

0

0.001

0.002

0.003

0.004

-1000 -500 0 500 1000

40

80

120

160

50 100

-6 -4 -2 0 2 4 6

-500

0

500

Ivison et al. 1998, MNRAS 298, 583Frayer et al. 1998, ApJ, 506, L7Genzel et al. 2003, ApJ, 584, 633

Mdyn(R<8kpc) ~ 2-3x1011 MO

Most of which is baryonic


SMMJ14011+0252 (z=2.51)

Ivison et al. 2001 ApJ 561, L45Frayer et al. 1999, ApJ, 514, L13Downes & Solomon 2003 ApJ 582, 37


An IRAM PdBI CO Survey of SMGs(Genzel, Ivison, Neri, Bertoldi, Blain, Chapman, Cox, Greve, Neri, Omont, Smail,

Tacconi)

We are undertaking a first systematic CO survey of dust-enshrouded starburst galaxies at high redshifts

Bright (S850>5mJy) submm-selected galaxies detected in the radio. This population is responsible

for ~25% of the submm background.


Duty-cycle and current status:

• SCUBA/MAMBO sources with VLA 1.4GHz counterparts (Lockman E, ELAIS N2, SSA 22, SSA13, HDF-N etc).

• Keck follow-up spectroscopy with LRIS-B: ~70 redshifts, <z>=2.4

We are undertaking a first systematic CO survey of dust-enshrouded starburst galaxies at high redshifts

An IRAM PdBI CO Survey of SMGs(Genzel, Ivison, Neri, Bertoldi, Blain, Chapman, Cox, Greve, Neri, Omont, Smail,

Tacconi)


Keck (LRIS-B + NIRSPEC) spectroscopy

Chapman et al. (2003)

Ivison et al. (2002)



An IRAM PdBI CO Survey of SMGs



• PdBI follow-up for redshift confirmation (2-3 tracks each)

• High-resolution PdBI follow-up for spatially resolved CO dynamics





• PdBI follow-up for redshift confirmation (2-3 tracks each)

• High-resolution PdBI follow-up for spatially resolved CO dynamics

• Status winter 2004: 7 (+1) new CO detections, 6 non-detections - the number of SMGs detected in CO almost tripled!




First results Neri et al. (2003)

z=2.509 z=3.349 z=2.380



Greve et al. (2005)


An IRAM PdBI CO Survey of SMGs ID Transition zspec zCO FWHM ICO

Our Detections km/s Jy km/sSMMJ02396-0134 (2-1) 1.062+-0.001 1.062+-0.002 780+-60 3.4+- 0.3SMMJ13120+4242 (4-3) 3.405+-0.001 3.408+-0.002 530+-50 1.7+- 0.3 SMMJ16366+4105 (3-2) 2.454+-0.001 2.450+-0.002 870+-80 1.8+- 0.3SMMJ16371+4053 (3-2) 2.374+-0.001 2.380+-0.004 830+-130 1.0+- 0.2 SMMJ22174+0015 (3-2) 3.098+-0.002 3.099+-0.004 780+-100 0.8+- 0.2 SMMJ04431+0210 (3-2) 2.5092+-0.0008 2.5094+-0.0002 350+-60 1.4+-0.2SMMJ09431+4700 (4-3) 3.349+-0.001 3.3460+-0.0001 420+-50 1.1+-0.1 SMMJ16368+4057 (3-2) 2.380+-0.002 2.3853+-0.0014 840+-110 2.3+-0.2 (7-6) . . . 2.383+-0.002 . . . 1.1+- 0.2Non-detectionsSMMJ10523+5722 (3-2) 2.611+-0.001 2.5901 - 2.6119 . . . < 0.5SMMJ10524+5724 (3-2) 3.036+-0.001 3.0593 - 3.0318 . . . < 0.8SMMJ12360+6210 (3-2) 1.994+-0.001 1.9865 - 2.0015 . . . < 0.9SMMJ13123+4239 (3-2) 2.320+-0.001 2.3115 - 2.3300 . . . < 1.0SMMJ16363+4055 (3-2) 2.283+-0.001 2.2676 - 2.2919 . . . < 0.4

SMMJ16363+4056 (2-1) 1.495+-0.001 1.4802 - 1.5001 . . . < 0.8 Literature sourcesSMMJ02399-0136 (3-2) 2.803+-0.003 2.808+-0.002 710+-80 3.0+- 0.4 (3-2) . . . 2.8076+-0.0002 >1100 3.1+-0.4SMMJ14011+0252 (3-2) 2.562+-0.002 2.5653+-0.0003 200+-40 2.4+-0.3 (3-2) . . . 2.5652+-0.0001 190+-11 2.8+-0.3 (7-6) . . . 2.5651+-0.0002 170+-30 3.2+-0.5SMMJ16359+6612 (3-2) 2.5165+-0.0015 2.5168+-0.0003 500+-100 3.5+-0.1 (3-2) . . . 2.5174+-0.0002 500+-100 2.50+-0.12EROJ16450+4626 (2-1) 1.443+-0.001 1.439+-0.001 400+-20 1.40+-0.10 (5-4) . . . 1.440+-0.001 380+-20 1.35+-0.10 (1-0) . . . . . . . . . 0.6+-0.1

IDA Meeting, Copenhagen 20-21 Dec. 2004Greve et al. (2005)

Greve et al. (2005) Genzel et al. (2003) Neri et al. (2003)

Downes & Solomon (2003)


Neri et al. (2003) Greve et al. (2005)

z=1.062 z=2.803

z=2.562z=3.405z=3.349

z=2.509



Neri et al. (2003) Kneib et al. (2004) Greve et al. (2005)

Greve et al. (2005) Andreani et al. (2000) Greve et al. (2005)

Greve et al. (2005)

z=2.380 z=2.517 z=2.454

z=3.098z=1.439z=3.098



7 (+1) out of 13 (+1): detection rate of 54-57%. Remarkably good - comparable to the radio-ID fraction.

This confirms the <z>=2.4 redshift distribution of the bright, radio-detected SMG population (Chapman et al. 2003).





Greve et al. (2005)





H provides much more reliable estimate of the systemic (CO) redshift:

V(CO-Ly) V(CO-H) blueshifted: 5 0 redshifted : 2 0 zero offset : 1 4


Greve et al. (2005)


Bulk gas properties:

CO luminosity:

<LCO>=(3.8+-2.0)x1010K km/s 4x ULIRGs Gas masses (including HI+He):

<Mgas>=(3.0+-1.6)x1010MO

4x ULIRGs

So SMGs contains 3-4x more gas than local ULIRGs. Depletion of Gas as the merger progresses(Gao et al. 1999)?

Detection rate: z>2.4 : 5/7 (71%) z<2.4 : 2/6 (33%)Is this evidence for evolution in gas mass content?


Starformation efficiency:

• SMGs extend the (non-linear) FIR-CO correlation to higher z and luminosities

SMGs:

<LFIR/LCO>=(450+-170) LO MO-1

ULIRGs:

<LFIR/LCO>=(180+-130) LO MO-1

• Starformation efficiency might be higher in SMGs than in ULIRGs

• Tentative evidence of a FIR-CO correlation within the SMG sample itself


log(LCO) = 0.6 log(LFIR) + 2.4

Greve et al. (2005)



Starformation efficiency:

• SMGs extend the (non-linear) FIR-CO correlation to higher z and luminosities

SMGs:

<LFIR/LCO>=(450+-170) LO MO-1

ULIRGs:

<LFIR/LCO>=(180+-130) LO MO-1

• Starformation efficiency might be higher in SMGs than in ULIRGs

• Tentative evidence of a FIR-CO correlation within the SMG sample itself

Greve et al. (2005)


An IRAM PdBI CO Survey of SMGsDynamical masses:

• The double horn profiles are indicative of ordered orbital motion: either circum-nuclear disk or a merger.

• Assuming: 1) a conservative source size of D=0.5” (~3.7kpc at z=2.3) 2) random orbital inclinations (factor of /4) 3) Merger model*

<Mdyn>SMG = (1.2+-1.5) x 1011MO

* Toomre stability criterion:

Q = vs G 1 for a gaseous disk to be stable.

We find Q << 1 for Mgas=3x1010MO and R~4kpc.


Greve e al. (2005)


Dynamical masses:

• Velocity dispersion of SMGs is comparable to that of HzRGs and 3-4x that of ULIRGs.

• Assuming Mdyn ~ R2, andULIRGs:

Mdyn(R<0.6kpc) ~ 6x109MO,we findSMGs:

Mdyn(R<0.6kpc) ~ 4x1010MO

• The large line widths of SMGs strongly suggest that they are massive systems - with Mdyn comparable to HzRGs.


An IRAM PdBI CO Survey of SMGsGas mass fractions:

• Gas fraction:

SMGs : Mgas/Mdyn ~ 0.3

ULIRGs: ~ 0.16 (Downes & Solomon 1998)

• So SMGs appear to be more gas-rich than local ULIRGs, although

this is subject to uncertainties in the CO-H2 conversion factor and dynamical mass estimates.

But overall there is mounting evidence that SMGs are neither high-z replicas of local ULIRGs, nor simply scaled up versions.

Rather SMGs are more gas-rich and seem to form stars more efficiently (caveat: CO doesn’t trace the dense starforming gas, HCN does!)


An IRAM PdBI CO Survey of SMGsGas consumption time-scale and baryonic masses:

• The median starformation rate is <SFR>=720 MO yr-1, hence the duration of the ‘SCUBA/MAMBO’-phase is:

= M(H2)/SFR ~ 40Myr

• This is a lower limit since it assumes continuous starformation and ignores negative feedback and the possibility of HI falling in from outer regions.


An IRAM PdBI CO Survey of SMGsGas consumption time-scale and baryonic masses:

• The median starformation rate is <SFR>=720 MO yr-1, hence the duration of the ‘SCUBA/MAMBO’-phase is:

= M(H2)/SFR ~ 40Myr

• This is a lower limit since it assumes continuous starformation and ignores negative feedback and the possibility of HI falling in from outer regions.

• The median V-band restframe luminosity is 2 x 1011LO, which implies

median stellar mass of M* ~ 3 x 1010 MO (Smail et al. 2004).

So the typical baryonic mass is Mbar ~ 6 x 1010 MO - comparable to the masses of local L* galaxies. And SMGs are baryon-dominated in their

inner regions: Mbar/Mdyn ~ 0.5. Assembling that much baryonic matter so early is a severe challenge for models!


Implications for Models of Galaxy Formation

Greve et al. (2005)

A fundamental test-bed for galaxyformation models is the assemblyof massive baryonic galaxies.

Co-moving number density of

Mbar = 6 x 1010MO is

n(M>Mbar) ~ 5 x 10-6 Mpc-3

Corrected for our CO detection Fraction (0.53) and finite surveyvolume.


Implications for Models of Galaxy Formation

A fundamental test-bed for galaxyformation models is the assemblyof massive baryonic galaxies.

Co-moving number density of

Mbar = 6 x 1010MO is

n(M>Mbar) ~ 5 x 10-6 Mpc-3

Corrected for our CO detection Fraction (0.53) and finite surveyvolume.

This is a lower limit since we mustcorrect for the finite life time ofSMGs:

(2.0-3.5)/SMG = 1.5Gyr/(40-200)Myr = 8-38

1011

Mo

7x1010

Mo

5x1010

Mo

Greve et al. (2005)

High-resolution PdBI observations of SMGs

- a taste of ALMA


Tacconi et al. in prep.

1.3mm continuum, beam 0.7”x0.6”

SMMJ09431+4700: H6 + H7 (both radio sources) are part of the same

physical structure - separation 22kpc



SMMJ09431+4700:

CO(4-3) is detected in H7

(but not H6).

Tentative evidence for a

blueshifted filament of gas

between H7+H6.


- a taste of ALMA



SMMJ09431+4700:

CO(4-3) is detected in H7

(but not H6).

Tentative evidence for a

blueshifted filament of gas

between H7+H6.

We have ‘tasted’ what we

might expect to achieve

with ALMA!


- a taste of ALMA



SMMJ163681+4057:


- a taste of ALMA

The Future…


• CO is great! But…

• It doesn’t trace the dense starforming gas

• Need high-density tracers such as HCN

• Other molecular/atomic lines, e.g. CI

• Ultimate goal: detail ISM studies at high-z as well as ‘blind’ CO surveys.

…is here and it’s interferometrical!

The Future…


…is here and it’s interferometrical!• CO is great! But…

• It doesn’t trace the dense starforming gas

• Need high-density tracers such as HCN

• Other molecular/atomic lines, e.g. CI

• Ultimate goal: detail ISM studies at high-z as well as ‘blind’ CO surveys


The Future…


The Future…

Courtesy Jesper Sommer Larsen

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An IRAM PdBI CO Survey of Luminous Submm Galaxies A spearhead project for ALMA IDA Meeting,...

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