Panchromatic population synthesis studies of galaxies Laura Silva (INAF-Trieste, It) Sandro Bressan (INAF-Padova, It), Gian Luigi Granato (INAF-Padova, It), Pasquale Panuzzo (INAF -Padova, It), Olga Vega (INAOE -Puebla, Mx) Outline: * Modelling UV to radio SED of galaxies with GRASIL (short summary) * Detailed analysis of galaxy SEDs with GRASIL to retrieve physical information: (1) Early-type galaxies in the Virgo cluster: NGC4435 (with SF activity ) (2) Attenuation in spiral galaxies (3) SED analysis of ULIRGs including radio

(Very brief) Description of GRA(phite)SIL(icate) (Silva et al 98, Silva 99, Granato et al 00, Bressan et al 02, Silva et al 03, Panuzzo et al 03, Vega et al 05) 3 dusty environments: dense phase ISM (star forming Molecular Clouds), diffuse phase (cirrus)  clumping of stars and dust, dusty envelopes of AGB stars Stars are born within MCs and gradually escape as a function of their age  age- dependent extinction Stars and dust are distributed in a bulge (King profile) + disk (double exponential profile) geometry Radiative transfer exactly solved in MCs, with approximation in the cirrus (reasonable computing time) Dust includes big grains, very small grains and PAHs. The emission is appropriately computed for each component UV-to radio SEDs (continuum & nebular lines)

- - - emission from star forming MCs ….. emission from cirrus (diffuse ISM).-.-.-extincted stars ___ non extincted stars Input SF (and metallicity) history (“classical” chemical evolution code or galaxy formation model)

NGC5253 SSC 5

(1) Early-type galaxies in Virgo: SED analysis of NGC4435 Systematic spectroscopic study with Spitzer IRS of 17 Early type galaxies along the Color-Magnitude relation in Virgo Cluster (cycle 1) Aim: *Optical+MIR SED as a tool to disentangle age and metallicity in passive E where the MIR is dominated by AGB dusty envelopes. *MIR to detect also possible signs of nuclear SF Result: * 13 galaxies with the 10  m bump expected from AGB dusty envelopes * 4 galaxies with MIR signs of SF activity

Modelling intermediate age stellar populations in the IR: accounting for AGB dusty envelopes in SSPs (Bressan, Granato, Silva 1998) The brightest stars in intermediate age (  100 Myr to a few Gyrs) stellar populations are AGB stars AGB stars are embedded within dusty envelopes originated by very strong stellar winds (  Mo/yr) We included the effect of AGB dusty envelopes in SSP: Spherical symmetry and v exp independent of r   =  (M,R,L,Z). Radiative transfer of the photospheric SED through the envelope computed with the Granato et al code.

SEDs for Single Stellar Populations

Age & Metallicity degeneracy hampers reconstructing the history of baryon assembly in the early universe, recorded in the fossil stellar populations (early type galaxies) Old & Metal Poor = Young & Metal Rich NO Dusty AGBs Lot of Dusty AGBs OPT: MIR: Age & metallicity Age Metallicity  Bressan, Granato, Silva 1998

Old Stellar Populations MIR emission from dusty (silicates) AGB Stars (Bressan, Granato & Silva 98) Degeneracy in the Optical Degeneracy in the MIR MIR + Optical NIR Removes degeneracy

13 galaxies (76%) with a broad and spatially extended 10  m emission feature 10Gyr SSP models with Z=0.008, 0.02, 0.05 SSP with 5Gyr Z=0.008 Dashed: mean outflow AGB star Dotted: C-rich star U Cam Bressan et al 2006

M giant sed model + circumstellar envelope model

NGC galaxies with MIR signs of SF activity: SED analysis of NGC4435 N4435: Circumnuclear disk (4”) source of IR emission - Interacting with NGC Opt classified LINER/HII (Ho et al 97) - MBH < 7.5e6 Msun  1/10 average MBH- L relation (Coccato et al 06) (5”)

NGC4435: Direct information from MIR (5”) PAH revealed by Spitzer: 10.7  m, complex at 17  m (16.9 & 17.4  m),  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 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 t esc, 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= Mo/yr, =0.75 Mo/yr Compatible with interaction ~ 100 Myr ago with NGC4438 M*SB=1.4% stellar mass, LSB=32% Lbol No need of AGN to fit the SED Refinment of parameters to reproduce H  and H  : disk scale radii for dust more extended than stars

NGC4435: full SED fit (5”) Spitzer/IRS MCs CIRRUS SF component Old component No dust SF comp Central 5” SED (Galex, JHK, IRAC, MIPS, IRAS, radio) Starburst + old component Grid of models with GRASIL: * exp SFR (e-folding, age )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 t esc, 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= Mo/yr, =0.75 Mo/yr Consistent with interaction with NGC4438 (Vollmer et al 05: direct ISM-ISM interaction  100Myr ago, tidal interaction older) M*SB=1.4% stellar mass 5” ( 0.3% total aperture stellar mass ) LSB=32% Lbol 5” ( 8% total aperture 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 Attenuation curve resulting from age- dependent extinction and spatial distributions of stars and dust Average Galactic extinction curve (adopted for dust intrinsic properties)

(2) Attenuation in spiral galaxies Panuzzo et al astro-ph/ b=SFR/ Analysis of a sample of GALEX NUV-selected late type galaxies (Buat et al 2005, Iglesias-Paramo et al 2006) Meurer et al 1999 UV-bright sb GRASIL models: geometrical age- dependent effects and intrinsic dust properties effects b=0.25 b= A A

No age-dependent extinction: only diffuse dust, stars smoothly distributed independently from age Sequence of models with increasing dust content (1  m polar opt depth = ) 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, Myr Reddest data require tesc>30Myr

Age-dependent extinction due to cirrus only Stars younger than t thin with smaller disk scale height than older, dust in between Sequence of models with increasing dust content and t thin = Myr Age-dependent extinction due to MCs and cirrus Sequence of models with increasing dust content in the cirrus and t thin = Myr

Attenuation curves Only cirrus age- dependent extinction MCs+cirrus age- dependent extinction Granato et al 2000 GALFORM+GRASIL simulated galaxy catalogues MW extinction curve Calzetti et al attenuation curve

(3) SED analysis of LIRGs and ULIRGs Sample of 24 LIRGs and ULIRGs (from Condon et al 1991) observed at 22 GHz + full SED 22 GHz data to better constrain the thermal 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 starburst (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

q (FIR/Radio) vs Radio slope Effect of free-free absorption: t 1.4 =1 a = Radio Slope GHz Models evolve from left to right as NTh-emission from SN overcomes Th-emission from HII Does not affect higher n a q 1.4GHz q 8.4GHz Bressan,Silva,Granato 2002

Radio observations allow finer age tuning M82 ARP220 Bressan,Silva,Granato 2002

13/24 galaxies do not require AGN MCs cirrus NTh Th

11/24 require AGN MCs cirrus NTh Th AGN

* Esb=(Starburst age / e-folding starburst time scale) of the best fit to quantify the phase of the starburst (Vega et al 2005) * No apparent correlation between sb phase and presence of AGN Early phase Esb < 0.2 Peak starburst phase Esb= galaxies Old starburst phase Esb=2-4 6 galaxies Post starburst phase Esb>4 1 galaxy  = only SB  = SB+AGN

)Early starburst phase: warm FIR and cold MIR colors. The few newly formed stars still deep inside their MCs. SED dominated by emission from MCs but the intensity of the radiation field has not reached its peak value. In our models this phase has age b /t b ~ 0.05 to )Starburst peak phase, most massive stars are produced, SED dominated by the hot dust emission from MCs. The starburst reaches the hottest FIR colours and the lowest relative PAH emission. age b /t b ~ Young stars are still mostly embedded in the parent MCs. 3)Evolved starburst phase, the number of newly formed stars has drastically decreased, most of the still hot stars are out of their MCs and heat the cirrus. Emission dominated by the cirrus component, age b /t b ~ 2.0 to )Post-starburst phase: ageb/tb >4, current SFR mainly due to the quiescent disk and all the stars formed during the starburst are now outside the MC. FIR and MIR colors are evolving toward those of normal spiral galaxies. Vega et al 2005

 m LIR SB+AGN Only SB Fit for SB only: LIR/Mdense=183 Lo/Mo =5.25 average value for objects in common with G&S04 sample Fit SB+AGN Gao&Solomon 2004 LIR/Mdense=90 Lo/Mo Mdense/L_HCN=10 Mo/(Kkms-1pc2)^-1 Molecular mass associated with SF

SF effciency vs evolutionary status of the sb

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

GALSYNTH: a friendly WEB interface to run GRASIL Anyone can register and be a user Users have their workspaces Interactive editing of parameters, with explanations and bound checking, including iterations Sets of parameters can be saved, modified, reused. Batch jobs are executed on a pool of our computers When job completed, user is notified and downloads models

Derived AGN fractions in different bands

Best fit starburst parameters Age sb/ e-fold sb

Best fit AGN parameters

Some derived quantities