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Panchromatic population synthesis studies of galaxies

Panchromatic population synthesis studies of galaxies. Laura Silva – INAF Trieste Alessandro Bressan – INAF Padova Gian Luigi Granato – INAF Padova Pasquale Panuzzo – INAF Padova Olga Vega – INAOE Puebla.

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Panchromatic population synthesis studies of galaxies

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  1. Panchromatic population synthesis studies of galaxies Laura Silva –INAF Trieste Alessandro Bressan – INAF Padova Gian Luigi Granato – INAF Padova Pasquale 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

  2. (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: N4435: Circumnuclear disk (4”) - Interacting with NGC4438 - Opt classified LINER/HII (Ho et al 97) - MBH < 7.5e6 Msun (Coccato et al 06) NGC4435

  3. NGC4435: Direct information from MIR (5”) PAH revealed by Spitzer: 10.7m, complex at 17m (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%

  4. NGC4435: full SED fit (5”) Spitzer/IRS MCs No dust SF comp SF component Old component CIRRUS

  5. 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])

  6. 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-dependent extinction and spatial distributions of stars and dust

  7. (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 et al 1999 UV-bright sb b=0.25 GRASIL models: geometrical age- dependent effects and intrinsic dust properties effects + range of SF histories b=1.25

  8. 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 • 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 (1m polar opt depth =0.05-6.4) • MW and SMC dust composition • 2175A bump within NUV

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

  10. Attenuation law Only cirrus age- dependent extinction MCs+cirrus age- dependent extinction Granato et al 2000 GALFORM(Cole etal)+GRASIL(Silva etal)

  11. (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

  12. Radio observations allow Fine Age Tuning M82 ARP220

  13. q 1.4GHz The q-Radio slope diagram a = Radio Slope 1.4 - 8.4 GHz Models evolve from left to right as NT-emission from CCSN overcomes T-emission from HII a Effect of free-free absorption: t1.4=1 q 8.4GHz Does not affect higher n Bressan,Silva,Granato 2002

  14. 13 galaxies do not require AGN MCs NTh cirrus Th

  15. 12 require AGN

  16. Esb=(SB age/ e-folding time) of the best fit to quantify the phase of the starburst (Vega et al 2005) Post sb phase Esb>4 1 galaxy Old sb phase Esb=2-4 6 galaxies Peak sb phase Esb=0.2-2 18 galaxies Early phase Esb=0.05-0.2

  17. Fit SB+AGN SB+AGN Fit for SB only: LIR/Mden=183Lo/Mo Mdens/L_HCN=5.25 Only SB 8-1000m LIR Gao&Solomon 2004 LIR/Mdens=90 Lo/Mo Mdens/L_HCN=10

  18. 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

  19. (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

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