Panchromatic population synthesis studies of galaxies

Laura Silva –INAF TriesteAlessandro Bressan – INAF PadovaGian Luigi Granato – INAF PadovaPasquale Panuzzo –INAF Padova

Olga Vega – INAOE Puebla

Aim:

detailed analysis of galaxy SEDs with GRASIL (Silva et al) to retrieve physical information

Specific topics:

(1) NGC4435: Early-type galaxy with SF activity in the Virgo cluster (2) Attenuation in spiral galaxies(3) SED analysis of ULIRGs including radio

(1) SED analisys of NGC4435 Systematic spectroscopic study with Spitzer IRS of 17 Early type galaxies along the CM relation in Virgo Cluster (PID 3419 cycle 1 - PI A. Bressan):

13 galaxies with the 10 m bump: Optical+MIR SED as a tool to disentangle age and metallicity in passive E where the MIR is dominated by AGB dusty envelopes.

4 galaxies with MIR signs of SF activity:

NGC4435

N4435: Circumnuclear disk (4”) - Interacting with NGC4438 - Opt classified LINER/HII (Ho et al 97) - MBH < 7.5e6 Msun (Coccato et al 06)

NGC4435: Direct information from MIR (5”)

PAH revealed by Spitzer: 10.7m, complex at 17m (16.9 & 17.4 m), 19.07 m

Known PAHs: 6.2, 7.7, 8.2, 8.6, 11.2, 11.9, 12.7, 13.5, 14.5, 15.9, 16.4 m

Only low inization emission lines - [NeIII]15.5/[NeII]12.8=0.38 comparing to CLOUDY models AGN < 2%

NGC4435: full SED fit (5”)Spitzer/IRS

MCs

CIRRUS

SF component

Old component

No dust SF comp

NGC4435: full SED fit•Central 5” SED (Galex, JHK, IRAC, MIPS, IRAS, radio) + nebular lines (H , H , [NeII]12.8)

•Starburst + old component

•Grid of models with GRASIL: * exp SFR (e-folding , age ) * 2 phase ISM (opt depth of MCs 1, escape time scale of young stars from MCs tesc , Mmol/Mgas, disk geometry for stars and dust i=45°, dust/gas metallicity)

Derived quantities: •Nuclear disk in a post-starburst phase: e-fold=55 Myr, age=186 Myr, SFRc= 0.089 Mo/yr, <SFR>=0.75 Mo/yr Consistent with interaction with NGC4438

•M*SB=1.4% stellar mass 5” , 0.3% total stellar mass LSB=32% Lbol 5” , 8% total Lbol

•No need of AGN to fit the SED consistent with MIR lines

•Solar metallicity from fit of broad band SED + ionizing flux -> good agreement with observed MIR lines ([NeII], [NeIII], [ArII], [SIII])

NGC4435: attenuation law

Refinment of parameters to reproduce H and H : disk scale radii for dust more extended than stars

Attenuation law resulting from age-dependentextinction and spatial distributions of stars and dust

(2) Attenuation in spiral galaxies Padova+Marseille nodes, Panuzzo et al astro-ph/0612087

b=SFR/<SFR>Analysis of a sample of GALEX NUV-selected late type galaxies (Buat et al 2005, Iglesias-Paramo et al 2006)

Meurer e

t al 1

999

UV-bright s

b

GRASIL models: geometrical age- dependent effects and intrinsic dust properties effects + range of SF histories

b=0.25

b=1.25

•No age-dependent extinction: only diffuse dust, stars smoothly distributed indepently from age•Disc geometry, same scale lengths•Sequence of models with increasing dust content (1m polar opt depth =0.05-6.4)•MW and SMC dust composition•2175A bump within NUV

MW

SMC

•Age-dependent extinction due to MCs only, no cirrus• Sequence of models with increasing escape time scale from MCs, 0.5-64Myr•Reddest data require tesc>30Myr

•Age-dependent extinction due to cirrus only•Stars younger than tthin smaller disk scale height than older, dust in between•Sequence of models with increasing dust content and tthin=25-200 Myr

•Age-dependent extinction due to MCs and cirrus•Sequence of models with increasing dust content in the cirrus and tthin=25-200 Myr

Attenuation law

Only cirrus age- dependent extinctionMCs+cirrus age- dependent extinction

Granato et al 2000GALFORM(Cole etal)+GRASIL(Silva etal)

(3) SED analisys of ULIRGs

Sample of 25 LIRGs and ULIRGs observed at 22 GHz + 8 GHz + full SED

22 GHz data to better constrain the th radio emission and radio slope:•Thermal radio direct measure of SFR•Deviations from the FIR/Radio correlations and radio slope linked to the evolutionary status of a sb (Bressan, Silva, Granato 2002)

Large grid of GRASIL + AGN tori model SEDs (Granato et al 94,97)

Parameters grid for SF histories

Parameters grid for GRASIL

Parameters grid for AGN tori

Radio observations

allow Fine Age Tuning

M82ARP220

The q-Radio slope diagram

Effect of free-free absorption:

= Radio Slope 1.4 - 8.4 GHz

1.2

e2

ff

1.35-

T 0.082

GHz

ln pce

Models evolve from left to rightas NT-emission from CCSN overcomes T-emission from HII

Does not affect higher

q 1.4GHz

q 8.4GHz

Bressan,Silva,Granato 2002

13 galaxies do not require AGN

cirrus

MCs

Th

NTh

12 require AGN

Esb=(SB age/ e-folding time) of the best fit to quantify the phase of the starburst (Vega et al 2005)

Early phaseEsb=0.05-0.2

Peak sb phaseEsb=0.2-218 galaxies

Old sb phaseEsb=2-46 galaxies

Post sb phaseEsb>41 galaxy

8-1000m LIR

SB+AGNOnly SB

Fit for SB only:LIR/Mden=183Lo/Mo

Mdens/L_HCN=5.25

Fit SB+AGN

Gao&Solomon 2004LIR/Mdens=90 Lo/Mo

Mdens/L_HCN=10

AGN fraction• ~50% have an AGN, only ~10% have LAGN/Lbol>10%•No significant differences in the sb parameter values for pure sb and sb+agn

(SHORT) CONCLUSIONS

• If a large coverage of data is available a realistic model for galaxy SED is able to provide many fundamental physical quantities

• It is particularly important to have a model with predictive power rather than a template-type model when dealing with high z galaxies

• GRASIL is public and not so difficult to use

•Web interface: http://web.oapd.inaf.it/galsynth