Diapositiva 1

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
OpticalMIR 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 lt 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 -
NeIII15.5/NeII12.80.38 comparing to CLOUDY
models AGN lt 2
4
NGC4435 full SED fit (5)
Spitzer/IRS
MCs
No dust SF comp
SF component
CIRRUS
Old component
5
NGC4435 full SED fit

• Central 5 SED (Galex, JHK, IRAC, MIPS, IRAS,
  radio) nebular lines (H? , H? , NeII12.8)
• 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 i45, dust/gas ? metallicity)

• Derived quantities
• Nuclear disk in a post-starburst phase
  e-fold55 Myr, age186 Myr, SFRc 0.089 Mo/yr,
  ltSFRgt0.75 Mo/yr Consistent with interaction
  with NGC4438
• MSB1.4 stellar mass 5 , 0.3 total stellar
  mass LSB32 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 -gt 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 extin
ction and spatial distributions of stars and dust
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(2) Attenuation in spiral galaxies
PadovaMarseille nodes, Panuzzo et al
astro-ph/0612087
bSFR/ltSFRgt
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
b0.25
GRASIL models geometrical age- dependent
effects and intrinsic dust properties effects
range of SF histories
b1.25
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 tescgt30Myr

• 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

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• Age-dependent extinction due to MCs and cirrus
• Sequence of models with increasing dust content
  in the cirrus and tthin25-200 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 tthin25-200 Myr

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Attenuation law
Only cirrus age- dependent extinction
MCscirrus age- dependent extinction
Granato et al 2000 GALFORM(Cole
etal)GRASIL(Silva etal)
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(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
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Radio observations allow Fine Age Tuning
M82
ARP220
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The q-Radio slope diagram
q 1.4GHz
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 t1.41
q 8.4GHz
Does not affect higher n
Bressan,Silva,Granato 2002
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13 galaxies do not require AGN
MCs
NTh
cirrus
Th
15
12 require AGN
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Esb(SB age/ e-folding time) of the best fit to
quantify the phase of the starburst (Vega et al
2005)
Post sb phase Esbgt4 1 galaxy
Old sb phase Esb2-4 6 galaxies
Peak sb phase Esb0.2-2 18 galaxies
Early phase Esb0.05-0.2
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Fit SBAGN
SBAGN
Fit for SB only LIR/Mden183Lo/Mo Mdens/L_HCN5.
25
Only SB
8-1000?m LIR
GaoSolomon 2004 LIR/Mdens90 Lo/Mo Mdens/L_HCN1
0
18

• AGN fraction
• 50 have an AGN, only 10 have LAGN/Lbolgt10
• No significant differences in the sb parameter
  values for pure sb and sbagn

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(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