Lisa Kewley (CfA) Margaret Geller (CfA) Rolf Jansen (ASU) Mike Dopita (RSAA)
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Transcript of Lisa Kewley (CfA) Margaret Geller (CfA) Rolf Jansen (ASU) Mike Dopita (RSAA)
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
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)
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))
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