Lisa Kewley (CfA)Lisa Kewley (CfA)

Margaret Geller (CfA)Margaret Geller (CfA)Rolf Jansen (ASU)Rolf Jansen (ASU)

Mike Dopita (RSAA)Mike Dopita (RSAA)

SummarySummarySummarySummary

IntroductionIntroduction NFGS SampleNFGS Sample IR & HIR & HSFRsSFRs Radio SFRs Radio SFRs [OII] SFRs[OII] SFRs Abundances Abundances ConclusionsConclusions Future DirectionsFuture Directions

Why are SFRs important?Why are SFRs important?Why are SFRs important?Why are SFRs important?

Galaxy evolution Galaxy evolution

Star formation history of the universeStar formation history of the universe

Problem? Problem? SFRs do not agreeSFRs do not agree

Galaxy EvolutionGalaxy Evolution

Starburst99(Leitherer et al. 1999))

Stellar population age prediction

Cosmic Star Formation HistoryCosmic Star Formation History

Madau 1998

SFR from HSFR from H

Assumptions:Assumptions: solar abundancesolar abundanceno dustno dusttotal re-emission of ionizing photonstotal re-emission of ionizing photonsSaltpeter IMFSaltpeter IMF

SFR(H) = 7.9 x 10-42 L(H)

(Kennicutt 1998)

Infrared SFR Infrared SFR

Assumptions:Assumptions: young stars dominate emissionyoung stars dominate emission

large optical depthlarge optical depthcontinuous burst modelcontinuous burst modelSaltpeter IMFSaltpeter IMF

(Kennicutt 1998, Calzetti et al. 2000)

SFR(IR) = 4.5 x 10-44 L(IR) 7.9 x 10-44 L(FIR)~~

SFR(IR) & SFR(HSFR(IR) & SFR(Hin interacting starburst galaxiesin interacting starburst galaxies

Dopita, Pereira, Kewley & Dopita, Pereira, Kewley & Capaccioli (2002)Capaccioli (2002)

Sample:Sample:

Kewley et al. (2001)Kewley et al. (2001)

No reddening correctionNo reddening correction

DisagreementDisagreement

SFR(IR) & SFR(HSFR(IR) & SFR(Hin starburst galaxiesin starburst galaxies

Dopita, Pereira, Kewley & Dopita, Pereira, Kewley & Capaccioli (2002)Capaccioli (2002)

Also:Also:

Charlot et al. 2002Charlot et al. 2002

Rosa-Gonzalez et al. 2002Rosa-Gonzalez et al. 2002

Reddening correctionReddening correction

better agreementbetter agreement

Nearby Field Galaxy SurveyNearby Field Galaxy Survey

Sample selection:Sample selection:

198 galaxies objectively selected from the CfA galaxy survey198 galaxies objectively selected from the CfA galaxy survey (Davis & Peebles 1983, Huchra et al. 1983)(Davis & Peebles 1983, Huchra et al. 1983)

full range in Hubble typefull range in Hubble type

full range of absolute magnitudes in CfA surveyfull range of absolute magnitudes in CfA survey

Jansen et al. (2000)Jansen et al. (2000)http://http://cfa-www.harvard.edu/~jansen/nfgs/nfgssample.htmlcfa-www.harvard.edu/~jansen/nfgs/nfgssample.html

F(HF(H) :) : extinction corrected using Balmer Decrementextinction corrected using Balmer Decrement

corrected for stellar absorption corrected for stellar absorption

Integrated spectra

HIR SFRsIR SFRs

Kewley et al. Kewley et al. (2002)(2002)

HH uncorrected uncorrectedfor reddeningfor reddening

SFR(IR) = (2.7+/- 0.3) SFR(H)1.30 +/- 0.06

HIR SFRsIR SFRs

HH uncorrected uncorrectedfor reddeningfor reddening

Kewley et al. Kewley et al. (2002)(2002)

Reddening vs. FIR/H

log = (0.62 +/- 0.08) log {E(B-V)} + 2.66 +/- 0.06L(FIR)

L( H)

Kewley et al. Kewley et al. (2002)(2002)

HH corrected correctedfor reddeningfor reddening

SFR(IR) = (0.91+/- 0.04) SFR(H)1.07+/- 0.03

SFR(HSFR(H) & SFR(IR) agree to within 10%) & SFR(IR) agree to within 10%

Kewley et al. Kewley et al. (2002)(2002)

HIR SFRsIR SFRs

HH corrected correctedfor reddeningfor reddening

Kewley et al. Kewley et al. (2002)(2002)

K98 SFR K98 SFR constantsconstants

L(FIR) / L(HL(FIR) / L(H) => Empirical test) => Empirical test

L(FIR) / L(HL(FIR) / L(H) x k(FIR)/k(H) x k(FIR)/k(H) = 0.96 +/- 0.04) = 0.96 +/- 0.04

estimate the relationship between estimate the relationship between

L(FIR) / L(HL(FIR) / L(H) and SFR (FIR) / SFR (H) and SFR (FIR) / SFR (H))

Implications for NFGS galaxiesImplications for NFGS galaxies Implications for NFGS galaxiesImplications for NFGS galaxies

Young star formation responsible for HYoung star formation responsible for H & FIR & FIR

Dust heated close to the active SF regionsDust heated close to the active SF regions

global dust & gas relationship universalglobal dust & gas relationship universal

Infrared EmissionInfrared Emission

More IR cirrus in More IR cirrus in early-type spirals?early-type spirals?

dust heated by young OB starsdust heated by young OB starsphotospheres of evolved starsphotospheres of evolved stars

infrared “cirrus”infrared “cirrus”

Sauvage & Thuan (1992)Sauvage & Thuan (1992)

Stellar populations in early-type spiralsStellar populations in early-type spirals

Early-types Early-types deficient in deficient in young starsyoung stars

Kennicutt & Kent (1983)Kennicutt & Kent (1983)Sauvage & Thuan (1994)Sauvage & Thuan (1994)

IR detections

Implications for early-type spiralsImplications for early-type spiralsImplications for early-type spiralsImplications for early-type spirals

Either:Either: 1. Compensation effect?1. Compensation effect? Inoue 2002, Bell 2003Inoue 2002, Bell 2003 oror

2. Young star formation dominates2. Young star formation dominatesradio-FIR correlation: Gavazzi et al. 1986radio-FIR correlation: Gavazzi et al. 1986

1212m-FIR correlation: Shapley et al. 2001m-FIR correlation: Shapley et al. 2001

Radio SFRs Radio SFRs

SFR(1.4 GHz) = 1.2 x 10-21 L(1.4 GHz)

(Condon, Cotton, & Broderick 2002, Condon 1992)

Assumptions:Assumptions: Galactic relation between LGalactic relation between LNN & & SNSN

no dust no dust nonthermal spectral index ~ 0.8nonthermal spectral index ~ 0.8IMF slope ~ 2.5 for M > 5 MIMF slope ~ 2.5 for M > 5 MoSaltpeter IMF for M < 5 MSaltpeter IMF for M < 5 Mo

..

Radio & HRadio & H SFRs SFRs

Constant offsetConstant offsetSFR(20cm) = (0.54+/- 0.04) SFR(H)0.90 +/- 0.03

Kewley, Geller, & Kewley, Geller, & Jansen Jansen

(2003, (2003, in prepin prep))

Radio & IR SFRsRadio & IR SFRs

Constant offsetConstant offsetSFR(IR) = (0.54+/- 0.04) SFR(20cm)0.88 +/- 0.03

Kewley, Geller, & Jansen Kewley, Geller, & Jansen

(2003, (2003, in prepin prep))

Radio & HRadio & H SFR constants SFR constants

L(20cm) / L(HL(20cm) / L(H) => Empirical test) => Empirical test

L(20cm) / L(HL(20cm) / L(H) x C02/K98 constants ~ 2.4 +/- 0.2) x C02/K98 constants ~ 2.4 +/- 0.2

do notdo not agree with the empirical relationship agree with the empirical relationship between L(20cm) / L(Hbetween L(20cm) / L(H) )

possible causes: IMF differences, SN rate, ... possible causes: IMF differences, SN rate, ...

[OII] SFRs[OII] SFRs

Assumptions:Assumptions: solar abundancesolar abundance

no dustno dust

Saltpeter IMFSaltpeter IMF

SFR([OII]) = (1.4 +/- 0.4) x 10SFR([OII]) = (1.4 +/- 0.4) x 10-41-41 L([OII]) L([OII])

(Kennicutt 1998)

[OII] & H[OII] & H SFRs SFRs

SFR([OII]) = (1.51+/- 0.07) SFR(H)0.92 +/- 0.02

Kewley, Geller, & Jansen Kewley, Geller, & Jansen

(2003, (2003, in prepin prep))

[OII], H[OII], H and magnitude and magnitudeJansen et al. (2001)Jansen et al. (2001)

AbundancesAbundancesDerived using Kewley & Dopita (2002, ApJS, 142, 35)Derived using Kewley & Dopita (2002, ApJS, 142, 35)

[OII] SFR & abundance[OII] SFR & abundance

Kewley, Geller & Kewley, Geller & Jansen Jansen

(2003, in prep)(2003, in prep)

also Moustakas, also Moustakas, 2002, AAS, 200, 432002, AAS, 200, 43

ConclusionsConclusionsConclusionsConclusions

Reddening & stellar absorption correction Reddening & stellar absorption correction

SFR(IR) & SFR(HSFR(IR) & SFR(H) agree to within 10%) agree to within 10%

Systematic offset between Condon 2002 20cm Systematic offset between Condon 2002 20cm

constant and K98 constantsconstant and K98 constants

SFR[OII] depends on abundance (low metallicities)SFR[OII] depends on abundance (low metallicities)

FIR/HFIR/H & FIR/radio relations & FIR/radio relations

All IR NFGS star-forming galaxies are dominated by All IR NFGS star-forming galaxies are dominated by young SF in the FIR, Hyoung SF in the FIR, H, and radio., and radio.

Future DirectionsFuture DirectionsFuture DirectionsFuture Directions

NFGS J, H, K, L imaging survey (UKIRT) NFGS J, H, K, L imaging survey (UKIRT)

old stellar populations & hot dustold stellar populations & hot dust

HH images images young stellar populationsyoung stellar populations

Differences between K98 and C02 SFR constants: Differences between K98 and C02 SFR constants: Stellar population synthesis models => Stellar population synthesis models => IMFIMF Radio measurements => Radio measurements => SN rateSN rate