Conference summary

Catherine CesarskyESO

Moriond, March 2005

When UV meets infrared

• (and everything from gamma rays to radio)

• Do we see the same sources in UV and IR?

GALEX 24 micron MIPS

IRAC GOODS

Summary

1. By selection, UV galaxies and IR galaxies have very different characteristic IR/UV ratios (the means differ by a factor of 10). 2. The morphological and stellar mass distributions of the two populations have good overlaps (> 70%). IR galaxies tend to be more massive and earlier types, with an excess of interacting galaxies, and UV galaxies to be less massive and later types.3. UV galaxies are less clustered than IR galaxies.

4. Galaxies with the highest SFR (>100 M /yr, Ltot > 1012 L ),

are missed in the UV samples.5. A population of low metallicity (< 1/10 solar), low mass (<10^9 M ) dwarf UV galaxies (prototype I Zw 18) are `IR quiet’, with the IR/UV ratio ~ 0.3 or less. They occupy only a few percent of a UV selected sample.

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Moriond 2005VC

UV/mid-IR comparison of two LIRGsUV/mid-IR comparison of two LIRGs

Charmandaris, Le Floc’h, Mirabel, ApJ, 2004, 600, L15

At z~2: UV --> R-/I- band & ISO/CAM 7μm -> Spitzer/MIPS24.

The poor spatial at z~2 will result in blending of the emission from the unresolved interacting components. An increased scatter will thus be introduced in the observed optical to mid-IR colors of these galaxies, leading to a

systematic underestimation of their dust content.

7μm/UV ~ 800:10:35 7μm/UV ~ 330:160:190

Images: HST/STIS UV - Contours: ISOCAM 7μm

• Do we need UV to understand star formation?

• YES, at least in some cases (low obscuration)

Rest UV Traces Star Formation

Over Large Range of Specific Star Formation & SFR/Area

What gives???

gas ranges 20:1

gas 1.4 ranges 70:1

Milky Way

Luminous UV Galaxies

Low SurfaceBrightnessGalaxies

Early Type Gals

( )* *

** / age

M Mb

M tM= =

& &

&

Shortcut to SFH

• b-parameter vs. NUV-r color

– Obtain b from color alone– Works when no spectra are

available– Valuable for high z– Spread in x-direction due to

internal extinction

( )* *

** / age

M Mb

M tM= =

& &

&

NUV-r b

Rest UV Traces Star Formation

Over Large Range of Specific Star Formation

H and UV radial profiles Thilker, Meuer, et al

• Radial profile differences seen in other galaxies

• Not all galaxies show H deficit

UV

Ha

•Star clusters as indicators/ demonstrators of star formation

• Do we need IR to understand star formation?

• YES, especially for the brightest galaxies

• Can the different star formation indicators be reconciled?

• Sometimes…

Ha/UV in SDSSTreyer, Johnson, et al.

• Ha/UV shows systematic trend

Higher LUV, Blue NUV-r

L(Ha)/L(UV)~Kennicutt

Low LUV, Red NUV-r

L(Ha)/L(UV) > Kennicutt

OII line & UV luminosities underestimate SFR values by factors 5 to 100 for starbursts & LIRGs !

SFRs as estimated by UV, [OII] & IR(Hammer et al, Venice 2003, proceedings, astro-

ph/0401246)

SFRSFRNUVNUV vs. SFR vs. SFR

dustdust

Quite good agreement on average but...Quite good agreement on average but...lo

g S

FRdust (

Msu

n y

r-1)

log SFRNUV (Msun yr-1)

● At low values of At low values of AANUVNUV, the dust , the dust

emission emission underestimates the underestimates the total SFR because of total SFR because of the non negligible the non negligible NUV emission.NUV emission.● At high values of At high values of AANUVNUV, the NUV , the NUV

emission emission underestimates the underestimates the total SFR. total SFR. Problem with AProblem with ANUVNUV??

Two different trends are observed:Two different trends are observed:

log SFRNUV (Msun yr-1)

log S

FRN

UV/S

FRdust

Estimating extinctions and SFRs at z ~1

(Flores et al, 2004, A&A 415, 885)FORS2/ISAAC: 16 ISO galaxies, 0.4< z <1

- extinction corrected H SFRs are close to mid-IR estimates (Elbaz et al, 2002) for SFR < 150 MO/yr (i.e. below ULIRGs)

more robust SFR estimates

-luminous IR galaxies (not ULIRGs) dominates the cosmic star formation density at z~1 (confirmed by Spitzer, Le Floch et al, 2004)

less than 20% of the star formation density is coming from extremely dust enshrouded regions

•Deep IR surveys: do we understand what we see?

•Probably, but…

EBL: optical vs IR

CIRB~ 1.5 OPT IGL

In local universe, about 30% bolometric light in IR; LIRGs, ULIRGs produce 2% of bolometric luminosity

However,distant universe is IR.

Due to LIRGs? How distant?

LW3z=0

0.5

1

1.5

2

Typical galaxyspectra

K-corrections

LW3 15

LW2 6.7

CIRB peak: 140 m

Individual galaxies peak: 60 to 100 m

Peak shifted to 140 m

if z=0.4 to 1.3 (<z>~0.85)

15 m 8 m

z=0.85 z=0

140 m 80 m

ISOCAM deep surveys in LW3 (12-18 m):

Ideal to detect redshifted PAH for z~0.85 (or in general at z<1.5)

Number Counts• Roughly in agreement with

ISOCAM results • Some confused ISOCAM

sources are resolved by Spitzer• The HDF-N pilot study is not an

unbiased survey• Marleau et al. (2004) find 24

m number counts peak at fainter flux than 15 m counts

• difference b/w 15 and 24 m counts is not the result of confusion of ISOCAM sources or systematic differences between the observatories

From the MIR ? From the MIR ?

Local universe : correlation MIR – LIR Local universe : correlation MIR – LIR (Elbaz et al, 2002)

correlation radio-MIR correlation radio-MIR (Codon 1992, Yun et al, 2001)

or radio is a tracer of LIRor radio is a tracer of LIR

MIR + local templates or correlations => FIR=> LIR => SFRMIR + local templates or correlations => FIR=> LIR => SFR Chary & Elbaz 2001 Kennicutt 1998Chary & Elbaz 2001 Kennicutt 1998

Dale & Helou, 2002 Dale & Helou, 2002 Lagache et et al, 2004Lagache et et al, 2004

…… ……....

M82(disque)

(Laurent et al. 2000)

15 m vs IRIR vs IRAS 12 mIR vs ISOCAM 15 m

24m Spitzer-MIPS

15m ISOCAM

SED of a LIRG at z=0.69 (LIR~10SED of a LIRG at z=0.69 (LIR~1011.111.1 L L,SFR~22 M,SFR~22 Myr-1)yr-1)

The PAH bump exists at z=0.7The PAH bump exists at z=0.7

*

50 % stars born z<1.5 (70 % universe age)36 % @ z<1 (57 %)67 % @ z<2 (76 %)

Proportion of present-day stars born in LIRGs > 50 %==> Common phase experienced by all/most galaxies...

LIRGs and cosmic star formation

General 24m differential counts (this work, Chary et al. 2004, Papovich et al. 2004)

Model predictions Model predictions SS2424/S/S1515 as a function of z, Sas a function of z, S2424Model predictions Model predictions SS2424/S/S1515 as a function of z, Sas a function of z, S2424

S > 2-3 mJyS > 2-3 mJy dominated by dominated by objects with Sobjects with S2424/S/S15152-2.52-2.5

S S 0.3 mJy 0.3 mJy dominated by dominated by objects with Sobjects with S2424/S/S15 15 1.51.5

S < 0.2-0.3 mJyS < 0.2-0.3 mJy dominated dominated by objects with Sby objects with S2424/S/S15 15 > 2-3 > 2-3 -> NEW POPULATION !-> NEW POPULATION !

S > 2-3 mJyS > 2-3 mJy dominated by dominated by objects with Sobjects with S2424/S/S15152-2.52-2.5

S S 0.3 mJy 0.3 mJy dominated by dominated by objects with Sobjects with S2424/S/S15 15 1.51.5

S < 0.2-0.3 mJyS < 0.2-0.3 mJy dominated dominated by objects with Sby objects with S2424/S/S15 15 > 2-3 > 2-3 -> NEW POPULATION !-> NEW POPULATION !

R-band mag versus Flux@24μm

Rencontres de Moriond, March 6-12th 2005

80% completeness limit at 24μm

VERY hard to be complete in the redshift identification at any 24μm flux, using VVDS/GOODS/COMBO-17

IR luminosities in the CDFS

2635 sourceswith redshifts

* Modest IR emitters at 0<z<0.5

* ULIRGs : quite rare at 0<z<1

* LIRGS: significant contribution at z>0.5

* More « normal » starbursts are not negligible neither

80% completeness limit

Rencontres de Moriond, March 6-12th 2005

Star formation history at z<1

LIRGs/ULIRGs dominate beyond z~0.7

Chary & Elbaz 2001

Blain et al. 2002

Lagache et al. 2004

. . . . . .

_ _ _ _ _

ULIRGs

total

L >10 L .11

IR

L <10 L .11

IR

Rencontres de Moriond, March 6-12th 2005

Compilation by Hopkins 2004

Star formation history at z<1

LIRGs/ULIRGs dominate beyond z~0.7

AGN contribution ??* ISO/XMM : <20% (Fadda et al. 2002)* X-ray +IR bkg synthetic models : <5% (e.g., Silva et al. 2004)

First Spitzer results : <15% of sources flagged as AGNs by VVDS& COMBO-17 (see also SWIRE, Franceschini et al. 2005)

Rencontres de Moriond, March 6-12th 2005

* 55~65 % of 24μm sources at z<1 for flux>80μJy

Summary

* At 0<z<1, L* evolves at least by (1+z) ( exclude a pure density evolution)

3.5

* IR luminous galaxies start to dominate the SFRH at z>0.6

* LIRGs+ULIRGs = 70% of SFR at z=1

* Need a better understanding of IR SEDs : IRS GTO, MIPS SED mode...

Cornell University - Ithaca, December 1st 2004

• Is galaxy formation (the building up of galaxies) regular or episodic?

• Mostly episodic, even if we don’t know for sure why.

LIRGs: potentially double their masses in ~0.8 Gyr

SFR: [OII]3727Open symbols

From BE00:

Brinchman & Ellis 2000

SFR: IR & HRed dots: LIRGs (20-200 MO/yr)

Full squares: starbursts (<20M/yr)

How to account for the high LIRG fraction (15% of intermediate mass galaxies) ?

A specific population ?

LIRGs are continuously forming stars during 3.3 Gyrs (z=1 z=0.4)

they would multiply their masses by 2 x (3.3/0.8)=8.2 !!

BUT no trace of recent formation of massive galaxies, dominated by E/S0, with 3 1011<Mstar<31012MO

• Do we understand ultra luminous star forming galaxies?

• Yes, although debate on role of AGN not completely closed

Moriond 2005VC

The first 18

low-resolution

IRS spectra

of ULIRGs

Diversity!

is the name of the game…

• Highly luminous (ULIRG) systemsHighly luminous (ULIRG) systems• SFR ~ 1000 MSFR ~ 1000 M yr yr-1 -1

• Massive systemsMassive systems• Evidence for outflowing windsEvidence for outflowing winds

Progenitors of massive

elliptical galaxies?

Results of submm surveys

• Do we understand Luminous star forming galaxies?

• Errrrr, well…

Stellar properties of distant LIRGs

• b parameter: SFR/<SFR> = 5 +/-3

• Burst duration ~ 108 years

• Burst stellar mass fraction ~ 5-10 %

• M/Lz ~ 0.3 (SDSS 1.6)

• Stellar masses: <M*> ~ 5 x1010 M

Large UVLGs = LIRGs ?

• UV Luminosity Density from UVLG x30 from z=0 to z=1• 25% of FUV luminosity density at z=1 from UVLG• SFR from LIRGs x20 from z=0 to z=1• > 70% of dust-enshrouded SFR density at z=1 from LIRGs

Goldader et al. (2002)

Burgarella et al.(2005)

Conclusions The most UV luminous galaxies in the combined

GALEX/SDSS sample comprise two populations: Large UVLGs – rare, massive disk systems Compact UVLGs – small systems undergoing intense star

formation Compact UVLGs appear similar in many respects to

Lyman break galaxies UV Luminosity, star formation rate (selected) Size UV extinction Stellar mass, velocity dispersion Metallicity

Compact UVLGs may be useful analogs for LBGs

UV Luminous Galaxies (UVLGs)Dramatic Evolution to z=3 (DS, Ilbert, Arnouts

et al)

(1+z)2.5

Luminosity density ofUV luminous (LBG-analog)galaxies shows dramaticevolution: (1+z)5

LFUV,bol > 1010 Lsol

SFR > 10 Msol/yr

Steeper than QSOLD evolution (Boyle+Madau et al)

UVLGs producea significant fraction of LD at z = 1

Total

GALEX AIS + IRAS Bivariate SF Luminosity

Function

1000 GALEX+IRAS galaxies

LBG

LBG

Do AGNs play a role in galaxy

evolution?

Yes.

Chandra allows to separate the X-ray emission from the nucleus and the star-forming ring

Jet-Induced Star Formation in Centaurus A

S. G. Neff et al.

• New GALEX data:– Deep (~27 mag rms)– Wide field (1.2o)

• FUV emission (1500A) detected:

– along jet(s) for >25 kpc (shocks)

– where jet hits cold clouds (young stars)

– where inner jet is disrupted (???)

– possibly around radio lobes (young stars?)

FUV (1500A)NUV (2300A)

5 kpc ~

Minkowski’s Object

(cf. van Breugel)

FUV + HI Neff, Schiminovich et al.

Results for 65 Sey2: for central (median) 174 pc (65 Sey 2); 121 pc (14-rest)

Heterogeneous star formation histories.

● 10 SSP BC03 ages, Z=1 and 2.5 solar, plus a power law FC.

Some, dominated by old stars (t>2.5Ga), to 80% of the optical light;

Some show strong component of intermediate age stars (100Ma<t<1.4Ga);

Young clusters are ubiquitous (t<25Ma), in some cases to more than 50% of the light at 4020A and in several to 20%.

Strong FC component also present. This could be a genuine monster or a dusty young burst.

At least 3 of the 4 components present with significant strength (more than 10%) in any one galaxy.

A simple Ell galaxy + a power law (used many times before) does not apply to the bulk of Sey 2s.

Benson (2003)

Problem can be solved with extreme super-winds >5x1049 erg per solar mass required

Massive X-ray outflow in PDS 456

Reeves et al. (2003)

XMM EPIC pn/MOS

Conclusions Overwhelming evidence for CDM hierarchical structure formation

Problems with semi-analytical galaxy formation models - mechanism required to terminate SF in massive gals - plus other problems…

AGN feedback is a likely solution - may be related to the origin of the M/ relation - could also explain high-mass cut-off & cluster heating problem

• Are galaxies sensitive to their large scale environment?

• Discussed yesterday.

Other problem:

•How to reconcile integrated and small scale properties?

V. Lebouteiller – Moriond 2005

Blue Compact DwarfsBlue Compact Dwarfs

Refs : Lebouteiller et al. (2003), Lecavelier et al. (2003), Aloisi et al. (2003), Thuan et al.(2005), Thuan et al. (2002), Lee et al. (2003)

NGC1705 NGC253 IZw18 IZw36 Markarian59 SBS0335-052

[N/H] [O/H]

[Si/H] [P/H]

[Ar/H] [Fe/H]

HII region (opt. +IR em. lines)HI region (UV abs. lines)

6/18

Distant star formation: what came first?

Consensus (purely theoretical):

1000 Mo stars