Understand Galaxy Understand Galaxy Evolution with IR Surveys:Evolution with IR Surveys:

Comparison between Comparison between ISOCAM 15-ISOCAM 15-m and Spitzer m and Spitzer 24-24-m Source Counts as a m Source Counts as a

ToolTool

Carlotta Gruppioni – INAF Carlotta Gruppioni – INAF OABOAB

La Thuile 08/03/05La Thuile 08/03/05

SummarySummarySummarySummary

General PerspectiveGeneral PerspectivePast:Past: ISOCAM Surveys ISOCAM SurveysPresent:Present: from ISOCAM to Spitzer : What from ISOCAM to Spitzer : What can we learn from the comparison can we learn from the comparison between 15- and 24-between 15- and 24-m?m?

Future:Future: from ISOCAM and Spitzer to from ISOCAM and Spitzer to Herschel and ALMAHerschel and ALMA

General PerspectiveGeneral PerspectivePast:Past: ISOCAM Surveys ISOCAM SurveysPresent:Present: from ISOCAM to Spitzer : What from ISOCAM to Spitzer : What

can we learn from the comparison can we learn from the comparison between 15- and 24-between 15- and 24-m?m?

Future:Future: from ISOCAM and Spitzer to from ISOCAM and Spitzer to Herschel and ALMAHerschel and ALMA

General PerspectiveGeneral PerspectiveGeneral PerspectiveGeneral Perspective

Locally stars form in giant Locally stars form in giant molecular clouds, where molecular clouds, where opticaloptical and and UVUV light is strongly light is strongly absorbed byabsorbed by DUSTDUST

Thanks to Thanks to IRASIRAS we know that we know that galaxies forming stars at galaxies forming stars at > 20 M> 20 M/yr/yr radiate the bulk of their luminosity radiate the bulk of their luminosity above 5 above 5 mm:: LIGS:LIGS: 11 11 log(L log(LIRIR/L/L) ) 12 12ULIGS:ULIGS: 12 12 log(L log(LIRIR/L/L) ) 1313

Locally stars form in giant Locally stars form in giant molecular clouds, where molecular clouds, where opticaloptical and and UVUV light is strongly light is strongly absorbed byabsorbed by DUSTDUST

Thanks to Thanks to IRASIRAS we know that we know that galaxies forming stars at galaxies forming stars at > 20 M> 20 M/yr/yr radiate the bulk of their luminosity radiate the bulk of their luminosity above 5 above 5 mm:: LIGS:LIGS: 11 11 log(L log(LIRIR/L/L) ) 12 12ULIGS:ULIGS: 12 12 log(L log(LIRIR/L/L) ) 1313

In the Past, when galaxies were In the Past, when galaxies were moremore gaseousgaseous and formed the bulk of their and formed the bulk of their present-day stars, it would be logical present-day stars, it would be logical to expect to detect a large populationto expect to detect a large population of of LIGs/ULIGsLIGs/ULIGs. .

ISO observationsISO observations showed that showed that GalaxyGalaxy Formation could not be understoodFormation could not be understood without accounting for without accounting for dust extinctiondust extinction as a major ingredient as a major ingredient

In the Past, when galaxies were In the Past, when galaxies were moremore gaseousgaseous and formed the bulk of their and formed the bulk of their present-day stars, it would be logical present-day stars, it would be logical to expect to detect a large populationto expect to detect a large population of of LIGs/ULIGsLIGs/ULIGs. .

ISO observationsISO observations showed that showed that GalaxyGalaxy Formation could not be understoodFormation could not be understood without accounting for without accounting for dust extinctiondust extinction as a major ingredient as a major ingredient

ISO SURVEYSISO SURVEYSISO SURVEYSISO SURVEYS

Mid-IRMid-IR: : ISOCAMISOCAM (at (at 15 15 mm a a LIGLIG is is visible up to visible up to zz~1.3~1.3))

- Several Surveys were performed in- Several Surveys were performed in

Garanteed TimeGaranteed Time ( (IGTES: IGTES: 0.1 < S < 0.5 0.1 < S < 0.5 mJymJy; ; Elbaz et al. 1999Elbaz et al. 1999) and ) and Open TimeOpen Time ((ELAIS: ELAIS: 0.5 < S < 150 mJy0.5 < S < 150 mJy; ; Oliver Oliver

et al. 2000; Rowan-Robinson et al. 2004et al. 2000; Rowan-Robinson et al. 2004) )

Mid-IRMid-IR: : ISOCAMISOCAM (at (at 15 15 mm a a LIGLIG is is visible up to visible up to zz~1.3~1.3))

- Several Surveys were performed in- Several Surveys were performed in

Garanteed TimeGaranteed Time ( (IGTES: IGTES: 0.1 < S < 0.5 0.1 < S < 0.5 mJymJy; ; Elbaz et al. 1999Elbaz et al. 1999) and ) and Open TimeOpen Time ((ELAIS: ELAIS: 0.5 < S < 150 mJy0.5 < S < 150 mJy; ; Oliver Oliver

et al. 2000; Rowan-Robinson et al. 2004et al. 2000; Rowan-Robinson et al. 2004) )

Source counts exhibit a Source counts exhibit a strong excessstrong excess of sources of sources below Sbelow S1515 ~2 mJy~2 mJy..

Galaxies above this flux density do fall Galaxies above this flux density do fall within the within the “no-evolution region”“no-evolution region” (ELAIS(ELAIScounts: Gruppioni et al. ’02) counts: Gruppioni et al. ’02)

The predicted The predicted Extragalactic BackgroundExtragalactic BackgroundLight at 15 Light at 15 mm is: is:

EBLEBLmodelsmodels(15 (15 m) ~ 3.3 nW mm) ~ 3.3 nW m-2-2 sr sr-1-1

ISOCAMISOCAM resolves resolves ~73 %~73 % of EBL of EBL

Source counts exhibit a Source counts exhibit a strong excessstrong excess of sources of sources below Sbelow S1515 ~2 mJy~2 mJy..

Galaxies above this flux density do fall Galaxies above this flux density do fall within the within the “no-evolution region”“no-evolution region” (ELAIS(ELAIScounts: Gruppioni et al. ’02) counts: Gruppioni et al. ’02)

The predicted The predicted Extragalactic BackgroundExtragalactic BackgroundLight at 15 Light at 15 mm is: is:

EBLEBLmodelsmodels(15 (15 m) ~ 3.3 nW mm) ~ 3.3 nW m-2-2 sr sr-1-1

ISOCAMISOCAM resolves resolves ~73 %~73 % of EBL of EBL

Nature of ISOCAM galaxiesNature of ISOCAM galaxiesNature of ISOCAM galaxiesNature of ISOCAM galaxies

Most are Most are star-forming galaxiesstar-forming galaxies, often , often in small groups and showing in small groups and showing irregular/merging morphologiesirregular/merging morphologies. .

from Shallow Surveys (i.e. ELAIS;from Shallow Surveys (i.e. ELAIS; La Franca, Gruppioni et al. ’04La Franca, Gruppioni et al. ’04) : ) : <L<L1515> > ~ 10~ 1010 10 LL , <z> ~ 0.2 , <z> ~ 0.2 from Deep Surveys (i.e. IGTES; from Deep Surveys (i.e. IGTES; Elbaz Elbaz et et al. ’99,’01al. ’99,’01) : <L) : <L1515> > ~ 10~ 101111 L L , <, <z> z> 0.80.8 LIGLIG is an is an important phase in galaxy important phase in galaxy lifelife: a galaxy might experience : a galaxy might experience several several bursts of intense SFbursts of intense SF

Most are Most are star-forming galaxiesstar-forming galaxies, often , often in small groups and showing in small groups and showing irregular/merging morphologiesirregular/merging morphologies. .

from Shallow Surveys (i.e. ELAIS;from Shallow Surveys (i.e. ELAIS; La Franca, Gruppioni et al. ’04La Franca, Gruppioni et al. ’04) : ) : <L<L1515> > ~ 10~ 1010 10 LL , <z> ~ 0.2 , <z> ~ 0.2 from Deep Surveys (i.e. IGTES; from Deep Surveys (i.e. IGTES; Elbaz Elbaz et et al. ’99,’01al. ’99,’01) : <L) : <L1515> > ~ 10~ 101111 L L , <, <z> z> 0.80.8 LIGLIG is an is an important phase in galaxy important phase in galaxy lifelife: a galaxy might experience : a galaxy might experience several several bursts of intense SFbursts of intense SF

< z > = 0.2< z > = 0.2 ELAIS-S1ELAIS-S1

< z > = 0.8< z > = 0.8HDFNHDFN

Cosmic EvolutionCosmic EvolutionCosmic EvolutionCosmic Evolution

Several authors have produced Several authors have produced backwardsbackwardsevolution modelsevolution models to reproduce to reproduce sourcesourcecountscounts and and redshift distributionsredshift distributions of of ISOCAM galaxies (and IR galaxies)ISOCAM galaxies (and IR galaxies)::

i.e.i.e. Devriendt & Guiderdoni ’00; Dole et al. ’00; Devriendt & Guiderdoni ’00; Dole et al. ’00; Chary Chary & Elbaz ’01; Pearson ’01, ’05; Franceschini et al. & Elbaz ’01; Pearson ’01, ’05; Franceschini et al.

’01, ’03; Malkan & Stecker ’01; Xu et al. ’01, ’03’01, ’03; Malkan & Stecker ’01; Xu et al. ’01, ’03;; King & Rowan-Robinson ’03; Lagache, Dole & King & Rowan-Robinson ’03; Lagache, Dole & Puget ’03;Puget ’03; Pozzi,Pozzi,

Gruppioni, Oliver et al. ‘04Gruppioni, Oliver et al. ‘04

Several authors have produced Several authors have produced backwardsbackwardsevolution modelsevolution models to reproduce to reproduce sourcesourcecountscounts and and redshift distributionsredshift distributions of of ISOCAM galaxies (and IR galaxies)ISOCAM galaxies (and IR galaxies)::

i.e.i.e. Devriendt & Guiderdoni ’00; Dole et al. ’00; Devriendt & Guiderdoni ’00; Dole et al. ’00; Chary Chary & Elbaz ’01; Pearson ’01, ’05; Franceschini et al. & Elbaz ’01; Pearson ’01, ’05; Franceschini et al.

’01, ’03; Malkan & Stecker ’01; Xu et al. ’01, ’03’01, ’03; Malkan & Stecker ’01; Xu et al. ’01, ’03;; King & Rowan-Robinson ’03; Lagache, Dole & King & Rowan-Robinson ’03; Lagache, Dole & Puget ’03;Puget ’03; Pozzi,Pozzi,

Gruppioni, Oliver et al. ‘04Gruppioni, Oliver et al. ‘04

Cosmic EvolutionCosmic EvolutionCosmic EvolutionCosmic Evolution

All use a combination of All use a combination of luminosityluminosity andanddensity evolutiondensity evolution as a function of as a function of z z of the of the IR luminosity functionIR luminosity function at at 1515 or or 60 60 mm

The major output of these models The major output of these models was towas toshowshow that that LIGs/ULIGs LIGs/ULIGs were much were much more commonmore common in the pastin the past than they than they areare todaytoday(i.e.(i.e. Chary & Elbaz ’01Chary & Elbaz ’01:: comoving IR comoving IR luminosityluminosity due todue to LIGs LIGs ~ 70 times ~ 70 times largerlargerat z~1 than todayat z~1 than today))

All use a combination of All use a combination of luminosityluminosity andanddensity evolutiondensity evolution as a function of as a function of z z of the of the IR luminosity functionIR luminosity function at at 1515 or or 60 60 mm

The major output of these models The major output of these models was towas toshowshow that that LIGs/ULIGs LIGs/ULIGs were much were much more commonmore common in the pastin the past than they than they areare todaytoday(i.e.(i.e. Chary & Elbaz ’01Chary & Elbaz ’01:: comoving IR comoving IR luminosityluminosity due todue to LIGs LIGs ~ 70 times ~ 70 times largerlargerat z~1 than todayat z~1 than today))

Pozzi et al. ‘04Lagache et al.’04Pearson et al. ’01Franceschini ’01Franceschini upd.

1)1)DataData

ELAIS:ELAIS: larger OT ISO survey, larger OT ISO survey, 12 deg12 deg22 (PI: M. Rowan-Robinson) (PI: M. Rowan-Robinson)

ELAIS-S1 :ELAIS-S1 : field field ((4 sq.deg)4 sq.deg) completely analysed completely analysed Bologna + RomaBologna + Roma

15 15 m :m : 406 sources406 sources (‘ (‘Lari methodLari method’’, , Lari et al. Lari et al. ‘01‘01))

R-band :R-band : 81%81% (330/406) of the 15 µm (330/406) of the 15 µm sources optically identified sources optically identified RR2323 Spectra:Spectra: 72%72% (293/406) of the 15 (293/406) of the 15 m m source source spectroscopically classifiedspectroscopically classified R=23 at ESO+2dF R=23 at ESO+2dF (La Franca et al ‘04)(La Franca et al ‘04)

1)1)DataData

ELAIS:ELAIS: larger OT ISO survey, larger OT ISO survey, 12 deg12 deg22 (PI: M. Rowan-Robinson) (PI: M. Rowan-Robinson)

ELAIS-S1 :ELAIS-S1 : field field ((4 sq.deg)4 sq.deg) completely analysed completely analysed Bologna + RomaBologna + Roma

15 15 m :m : 406 sources406 sources (‘ (‘Lari methodLari method’’, , Lari et al. Lari et al. ‘01‘01))

R-band :R-band : 81%81% (330/406) of the 15 µm (330/406) of the 15 µm sources optically identified sources optically identified RR2323 Spectra:Spectra: 72%72% (293/406) of the 15 (293/406) of the 15 m m source source spectroscopically classifiedspectroscopically classified R=23 at ESO+2dF R=23 at ESO+2dF (La Franca et al ‘04)(La Franca et al ‘04)

The The Pozzi et al. (‘04)Pozzi et al. (‘04) 15 15 m model (a)m model (a)The The Pozzi et al. (‘04)Pozzi et al. (‘04) 15 15 m model (a)m model (a)

Relation LRelation L1515/L_opt of versus L/L_opt of versus L1515 Relation LRelation L1515/L_opt of versus L/L_opt of versus L1515

More luminous IR galaxy having larger L15/Lopt

More luminous IR galaxy having larger L15/Lopt

M51M51

M82M82

Arp220Arp220StarburstsStarbursts

Spirals Spirals

(Pozzi et al. 04)(Pozzi et al. 04)

Quantitative estimators:

Maximum likelihood (Marshall et al.’83) +

1/Vmax formalism (Schmidt ‘68)

4 Populations: Spiral (M51), Starburst (M82), AGN1 (Elvis et al. ‘94) & AGN2 (Circinus)

Evolution: Starburst : density & luminosity

Normal Spiral : no evolution

Agn1 & AGN2 : luminosity

NEW !!!! NEW !!!! L_15/L_opt to divide L_15/L_opt to divide starburst/spiralstarburst/spiral

Quantitative estimators:

Maximum likelihood (Marshall et al.’83) +

1/Vmax formalism (Schmidt ‘68)

4 Populations: Spiral (M51), Starburst (M82), AGN1 (Elvis et al. ‘94) & AGN2 (Circinus)

Evolution: Starburst : density & luminosity

Normal Spiral : no evolution

Agn1 & AGN2 : luminosity

NEW !!!! NEW !!!! L_15/L_opt to divide L_15/L_opt to divide starburst/spiralstarburst/spiral

The The Pozzi et al. (2004)Pozzi et al. (2004) 15 15 m m model (b)model (b)The The Pozzi et al. (2004)Pozzi et al. (2004) 15 15 m m model (b)model (b)2) Luminosity Function Method2) Luminosity Function Method2) Luminosity Function Method2) Luminosity Function Method

Pop. kl kd zbPop. kl kd zb------------------------- ------------------------- Spiral 0 0Spiral 0 0 0 0 Starb 3.5 3.8 1Starb 3.5 3.8 1 Agn1 2.6 0 2Agn1 2.6 0 2 Agn2 2-2.6 0 2Agn2 2-2.6 0 2(NGC1068 or (NGC1068 or Circinus)Circinus)

Starbursts Starbursts evolve in evolve in luminosity [as luminosity [as (1+z)(1+z)3.53.5] and ] and density density [(1+z)[(1+z)3.83.8]]up to up to z=1z=1

Pop. kl kd zbPop. kl kd zb------------------------- ------------------------- Spiral 0 0Spiral 0 0 0 0 Starb 3.5 3.8 1Starb 3.5 3.8 1 Agn1 2.6 0 2Agn1 2.6 0 2 Agn2 2-2.6 0 2Agn2 2-2.6 0 2(NGC1068 or (NGC1068 or Circinus)Circinus)

Starbursts Starbursts evolve in evolve in luminosity [as luminosity [as (1+z)(1+z)3.53.5] and ] and density density [(1+z)[(1+z)3.83.8]]up to up to z=1z=1

ISOCAM extragalactic counts at ISOCAM extragalactic counts at 1515mmISOCAM extragalactic counts at ISOCAM extragalactic counts at 1515mm

Luminosity Luminosity FunctionFunctionLuminosity Luminosity FunctionFunction

z-distributionz-distributionz-distributionz-distribution

From From ISOCAMISOCAM to to SpitzerSpitzer ......From From ISOCAMISOCAM to to SpitzerSpitzer ......

Spitzer Spitzer Telescope is Telescope is now providing now providing new new insight into the IR insight into the IR populationpopulation contributing to the contributing to the CIBCIB

Spitzer Spitzer Telescope is Telescope is now providing now providing new new insight into the IR insight into the IR populationpopulation contributing to the contributing to the CIBCIB

In particular with the In particular with the MIPS 24-MIPS 24-mm bandband,,which is which is starting to detectstarting to detect the the high-z high-z (z(z~~1.5-3.0) 1.5-3.0) analogs of theanalogs of the 15- 15-m m galaxiesgalaxies

In particular with the In particular with the MIPS 24-MIPS 24-mm bandband,,which is which is starting to detectstarting to detect the the high-z high-z (z(z~~1.5-3.0) 1.5-3.0) analogs of theanalogs of the 15- 15-m m galaxiesgalaxies

FLS Extragalactic Source Counts at 24 FLS Extragalactic Source Counts at 24 m:m:

comparison with some existing modelscomparison with some existing models

FLS Extragalactic Source Counts at 24 FLS Extragalactic Source Counts at 24 m:m:

comparison with some existing modelscomparison with some existing models

Franceschini et al. (2001) & Franceschini et al. (2001) & Rodighiero et al. (2004):Rodighiero et al. (2004): non-evolving normal pop, non-evolving normal pop, fast-evolving type-II AGNs & fast-evolving type-II AGNs & starbursts, starbursts, evolving type-I AGNsevolving type-I AGNs

Franceschini et al. (2001) & Franceschini et al. (2001) & Rodighiero et al. (2004):Rodighiero et al. (2004): non-evolving normal pop, non-evolving normal pop, fast-evolving type-II AGNs & fast-evolving type-II AGNs & starbursts, starbursts, evolving type-I AGNsevolving type-I AGNs

Lagache, Dole & Puget Lagache, Dole & Puget (2003):(2003): non-evolving non-evolving normal spirals and normal spirals and starbursts with L density starbursts with L density evolving with redshiftevolving with redshift

Lagache, Dole & Puget Lagache, Dole & Puget (2003):(2003): non-evolving non-evolving normal spirals and normal spirals and starbursts with L density starbursts with L density evolving with redshiftevolving with redshift

No-evolution model No-evolution model normalized to IRAS normalized to IRAS countscounts

No-evolution model No-evolution model normalized to IRAS normalized to IRAS countscounts

Galaxy evolution Galaxy evolution models:models:

Galaxy evolution Galaxy evolution models:models:

IRAS data points IRAS data points (transformed to 24 (transformed to 24 μμm) m) (Hacking & Soifer 1991; (Hacking & Soifer 1991; Sanders et al. 2003)Sanders et al. 2003)

IRAS data points IRAS data points (transformed to 24 (transformed to 24 μμm) m) (Hacking & Soifer 1991; (Hacking & Soifer 1991; Sanders et al. 2003)Sanders et al. 2003)

Marleau, Fadda, Storrie-Lombardi, et al. Marleau, Fadda, Storrie-Lombardi, et al. 20042004

Spitzer 24 Spitzer 24 m FLS compared to 15 m FLS compared to 15 m source countsm source counts (Marleau et al. ‘04)(Marleau et al. ‘04)

Spitzer 24 Spitzer 24 m FLS compared to 15 m FLS compared to 15 m source countsm source counts (Marleau et al. ‘04)(Marleau et al. ‘04)

Shaded region:Shaded region:24 24 m countsm counts

empty symbolempty symbol:15 15 mm countscounts

??

ELAIS ELAIS rangerange

Confirm Confirm existence existence of rapidly evolving of rapidly evolving population population discovered discovered by ISOCAM by ISOCAM

Question: Question: how to how to compare with compare with previous ISOCAM previous ISOCAM 1515 m counts?m counts?

ONLY one ratio ONLY one ratio assumed to convertassumed to convert

15 15 mm to 24 to 24 mm (S(S2424/S/S15151.2)1.2)

Confirm Confirm existence existence of rapidly evolving of rapidly evolving population population discovered discovered by ISOCAM by ISOCAM

Question: Question: how to how to compare with compare with previous ISOCAM previous ISOCAM 1515 m counts?m counts?

ONLY one ratio ONLY one ratio assumed to convertassumed to convert

15 15 mm to 24 to 24 mm (S(S2424/S/S15151.2)1.2) Gruppioni et al.’02Gruppioni et al.’02Gruppioni et al.’02Gruppioni et al.’02

Considering M82 (dominant population):ratio strongly dependent on z (because of PAHs)

S24/S15 2-2.5 z 0 S24/S15 1.2 z 1 S24/S15 > 5 2<z< 3

The ratio assumed by FLS team is fine for objects at z1 but NOT for ELAIS sources or higher z ones

Considering M82 (dominant population):ratio strongly dependent on z (because of PAHs)

S24/S15 2-2.5 z 0 S24/S15 1.2 z 1 S24/S15 > 5 2<z< 3

The ratio assumed by FLS team is fine for objects at z1 but NOT for ELAIS sources or higher z ones

Ratio for different IR prototype populationsRatio for different IR prototype populationsRatio for different IR prototype populationsRatio for different IR prototype populations

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 !

ContributionsContributions from different zfrom different z ContributionsContributions from different zfrom different z

While While galaxies with galaxies with z<1.3 dominate up to z<1.3 dominate up to SS0.3 mJy0.3 mJy, at lower , at lower fluxes the fluxes the new high-new high-z populationz population starts starts contributingcontributing for a for a significant fraction: significant fraction:

Anyway, Anyway, 70 %70 % background background qt qt z < 1.5z < 1.5

Spitzer Spitzer deep counts deep counts resolveresolve 75 % 75 % background background

While While galaxies with galaxies with z<1.3 dominate up to z<1.3 dominate up to SS0.3 mJy0.3 mJy, at lower , at lower fluxes the fluxes the new high-new high-z populationz population starts starts contributingcontributing for a for a significant fraction: significant fraction:

Anyway, Anyway, 70 %70 % background background qt qt z < 1.5z < 1.5

Spitzer Spitzer deep counts deep counts resolveresolve 75 % 75 % background background

First published 24 First published 24 m m datadataFLS team FLS team (Marleau et al. (Marleau et al. ‘04)‘04)

First published 24 First published 24 m m datadataFLS team FLS team (Marleau et al. (Marleau et al. ‘04)‘04)

After some months…After some months…

Swire team Swire team (Shupe(Shupe et al. et al. 2005, in preparation)2005, in preparation)

After some months…After some months…

Swire team Swire team (Shupe(Shupe et al. et al. 2005, in preparation)2005, in preparation)

A bit of criticism ...A bit of criticism ...A bit of criticism ...A bit of criticism ...

Our Model fit to other Spitzer Our Model fit to other Spitzer BandsBandsOur Model fit to other Spitzer Our Model fit to other Spitzer BandsBands

From From ISOCAMISOCAM to the to the longer longer ’s’s of of SpitzerSpitzer and and to to HERSCHELHERSCHEL

From From ISOCAMISOCAM to the to the longer longer ’s’s of of SpitzerSpitzer and and to to HERSCHELHERSCHEL

For the longer For the longer ’s ’s Fundamental Fundamental Ingredient: Ingredient: Galaxy SEDs (FIR Galaxy SEDs (FIR BUMP) !!!BUMP) !!!

For starburst galaxies For starburst galaxies we need we need “colder”“colder” SEDs than the SEDs than the prototypical prototypical M82M82 to fit the observed to fit the observed 70 and 160 70 and 160 mm source countssource counts

Use the phenomenological Use the phenomenological evolution modelevolution modelto make predictions also in the to make predictions also in the Herschel bands Herschel bands (PACS:75, 110, 170 (PACS:75, 110, 170 m;m; SPIRE: 250, 350, 500 SPIRE: 250, 350, 500 m)m)

For the longer For the longer ’s ’s Fundamental Fundamental Ingredient: Ingredient: Galaxy SEDs (FIR Galaxy SEDs (FIR BUMP) !!!BUMP) !!!

For starburst galaxies For starburst galaxies we need we need “colder”“colder” SEDs than the SEDs than the prototypical prototypical M82M82 to fit the observed to fit the observed 70 and 160 70 and 160 mm source countssource counts

Use the phenomenological Use the phenomenological evolution modelevolution modelto make predictions also in the to make predictions also in the Herschel bands Herschel bands (PACS:75, 110, 170 (PACS:75, 110, 170 m;m; SPIRE: 250, 350, 500 SPIRE: 250, 350, 500 m)m)

Strength of our ModelStrength of our ModelStrength of our ModelStrength of our Model

The The evolution parametersevolution parameters are are determined with a determined with a Maximum Maximum LikelihoodLikelihood fit of the fit of the 15-15-m LF, m LF, source counts and redshift source counts and redshift distributionsdistributions

TheThe starburst/normal galaxy starburst/normal galaxy separationseparation is based on a is based on a physical physical property of galaxies property of galaxies (L(L1515/L/Loptopt ratio) ratio) instead of being an instead of being an arbitraryarbitrary variablevariable

The The evolution parametersevolution parameters are are determined with a determined with a Maximum Maximum LikelihoodLikelihood fit of the fit of the 15-15-m LF, m LF, source counts and redshift source counts and redshift distributionsdistributions

TheThe starburst/normal galaxy starburst/normal galaxy separationseparation is based on a is based on a physical physical property of galaxies property of galaxies (L(L1515/L/Loptopt ratio) ratio) instead of being an instead of being an arbitraryarbitrary variablevariable

Weakness of our ModelWeakness of our ModelWeakness of our ModelWeakness of our Model

Is based on Is based on 15-15-m datam data only: only: Extend the ML fit to Extend the ML fit to all the MIR/FIR all the MIR/FIR observablesobservables (i.e. source counts and (i.e. source counts and redshift distributions) redshift distributions) find the find the best-best-fitting multi-fitting multi-solutionsolution

Use a Use a single SEDsingle SED for each galaxy for each galaxy population: population: Better using a Better using a SED librarySED library, with , with SEDs changingSEDs changing (i.e. becoming (i.e. becoming “colder”) “colder”) as function ofas function of LLIRIR oror z z (mainly for(mainly for starbursts starbursts))

Is based on Is based on 15-15-m datam data only: only: Extend the ML fit to Extend the ML fit to all the MIR/FIR all the MIR/FIR observablesobservables (i.e. source counts and (i.e. source counts and redshift distributions) redshift distributions) find the find the best-best-fitting multi-fitting multi-solutionsolution

Use a Use a single SEDsingle SED for each galaxy for each galaxy population: population: Better using a Better using a SED librarySED library, with , with SEDs changingSEDs changing (i.e. becoming (i.e. becoming “colder”) “colder”) as function ofas function of LLIRIR oror z z (mainly for(mainly for starbursts starbursts))

Separation Separation between between evolving evolving and non-evolvingand non-evolving population is population is sharp:sharp: Better considering a Better considering a smoother smoother variationvariation (i.e. different evolutions (i.e. different evolutions for different intervals of for different intervals of LL1515/L/Loptopt))

MUCH WORK TBDMUCH WORK TBD

SPITZER WILL SPITZER WILL HELP !!!HELP !!!

Separation Separation between between evolving evolving and non-evolvingand non-evolving population is population is sharp:sharp: Better considering a Better considering a smoother smoother variationvariation (i.e. different evolutions (i.e. different evolutions for different intervals of for different intervals of LL1515/L/Loptopt))

MUCH WORK TBDMUCH WORK TBD

SPITZER WILL SPITZER WILL HELP !!!HELP !!!