background slides from lecture 1
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Background Slides from Lecture 1. Multi-Wavelength SFR Diagnostics. `calorimetric’ IR. ( m) 1 10 100 1000. 24 m. 70 m. 160 m. 8 m. [OII]. P . H . UV. - PowerPoint PPT PresentationTRANSCRIPT
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Background Slides from Lecture 1
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Multi-Wavelength SFR Diagnostics
(m) 1 10 100 1000
H P 8 m 24 m 70 m 160 mUV [OII]
`calorimetric’ IR
Dale et al. 2007, ApJ, 655, 863
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0.1 1 10 100 mag (AV)
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GALEX FUV + NUV (1500/2500 A)
IRAC 8.0 m MIPS 24 m
H + R
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Spitzer Infrared Nearby Galaxies Survey (SINGS)
• complete IRAC, MIPS imaging of 75 nearby galaxies (3.5 – 160 m)
• IRS, MIPS radial strip maps (10 – 100 m)• IRS maps of centers, 75 extranuclear sources (5–37m)• ancillary imaging campaign covering UV to radio
Kennicutt et al. 2003, PASP, 115, 928
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UV Continuum Emission
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Ultraviolet stellar continuum: key advantages- direct photospheric measure of young massive stars- primary groundbased SFR tracer for galaxies at z>2-
However:- heavily attenuated by dust. Dust `correction’ methods
have limits (age-dust degeneracy).- dependent on the stellar population mix, usually
measures timescales of ~100 Myr.
Dale et al. 2007, ApJ, 655, 863
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GALEX Mission
- all-sky survey- 5 arcsec resolution- 1500 A, 2500 A to
AB = 20-21- 10,000 galaxies to
z=0.02- deep surveys to
AB = 25.5, 26.5- launched April
2003
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Steidel et al. 1996, ApJ, 462, L17
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Maeder, Meynet 1988, A&AS, 76, 411
Building an Evolutionary Synthesis Model
Kurucz 1979, ApJS, 40, 1
+
single star SED evolution model
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Leitherer et al. 1999, ApJS, 123, 3 “Starburst99”
“single burst models” “continuous star formation” models (single age star clusters)
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apply evolutionary synthesis maodels to constrain IMF
Kennicutt, Tamblyn, Congdon 1994, ApJ, 435, 22
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UV, Dust, and Age
Starbursts
(Calzetti et al. 1994,1995,1996,1997,2000, Meurer et al. 1999, Goldader et al. 2002)
26
A dusty stellar population may have similar UV characteristics of an old population
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26
Blue= starburstsRed= normal SF
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M51 Calzetti et al. 2005, ApJ, 633, 871
FUV, H, 24m 3.6, 4.5, 5.8, 8.0 m
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Photoionization Methods: Emission Lines
SINGG survey, G. Meurer et al. (NOAO)
• for ionization-bounded region observed recombination line flux scales with ionization rate
• ionization dominated by massive stars (M > 10 Mo), so nebular emission traces SFR in last 3-5 Myr
• ionizing UV reprocessed through few nebular lines, detectable to large distances
• only traces massive SFR, total rates sensitive to IMF extrapolation
• SFRs subject to systematic errors from extinction, escape of ionizing radiation from galaxy
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Kennicutt 1992, ApJS, 79, 255
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Local H Surveys
Survey Ngal Selection PI
GOLDMine 277 magnitude Coma/Virgo G. Gavazzi
MOSAIC ~1000 H Abell clusters R. Kennicutt
HGS 450 mag/volume field (<40 Mpc) P. James
SINGG/SUNGG* 468 HIPASS field (<40 Mpc) G. Meurer
STARFORM 150 volume field (<25 Mpc) S. Hameed
11HUGS *** 470 volume field (<11 Mpc) R. Kennicutt
AMIGA ~270 magnitude isolated field L. Montenegro
SINGS *** 75 multi-param <30 Mpc R. Kennicutt
SMUDGES ~1000 mag field dwarfs L. van Zee
UCM 376 obj prism field J. Gallego
KISS ~2200 obj prism field J. Salzer
** paired GALEX survey
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Photoionization Methods: Emission Lines
SINGG survey, G. Meurer et al. (NOAO)
• for ionization-bounded region observed recombination line flux scales with ionization rate
• ionization dominated by massive stars (M > 10 Mo), so nebular emission traces SFR in last 3-5 Myr
• ionizing UV reprocessed through few nebular lines, detectable to large distances
• only traces massive SFR, total rates sensitive to IMF extrapolation
• SFRs subject to systematic errors from extinction, escape of ionizing radiation from galaxy
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Leakage of Ionizing Flux at z ~ 3
Shapley et al. 2006, ApJ, 651, 688
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Shapley et al. 2006, ApJ, 651, 688
composite spectrum
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Calzetti et al., ApJ, submittedKennicutt & Moustakas, in prep
HII regions galaxies (integrated fluxes)
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Other Emission Lines
- H (0.48 m)
- Paschen- (1.9 m)
- Brackett- (2.2m)
- [OII] (0.37 m)
- Lyman- (0.12 m)
Scoville et al. 2000, AJ, 122, 3017
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Wavelength
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Moustakas, Kennicutt, Tremonti 2006, ApJ, 642, 775
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Moustakas et al. 2006, ApJ, 642, 775
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M83 = NGC 5236 (Sc)
SINGG: Survey for Ionization in Neutral-Gas
Galaxies
SINGG: Survey for Ionization in Neutral-
Gas Galaxies
11 Mpc Ha/Ultraviolet Survey (11HUGS)
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Lecture 2 Begins Here
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Dust Emission
• Interstellar dust absorbs ~50% of starlight in galaxies, re-radiates in thermal infrared (3–1000 m)
• Provides near-bolometric measure of SFR in dusty starbursts, where absorbed fraction ~100%
• Largest systematic errors from non-absorbed star formation and dust heated by older stars
• Different components of IR trace distinct dust species and stellar sub-populations
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FIR to SFR?
Dale et al. 2007
(m) 1 10 100 1000
8 m 24 m 70 m 160 m
`calorimetric’ IR
FIR - sensitive to heating from old stellar populations 8 m - mostly single photon heating (PAH emission)24 m - both thermal and single photon heating70 m and 160 m - mostly thermal, also from old stars
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NGC 628(M74)
C. Tremonti
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Moustakas et al. 2006, ApJ, 642, 775
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Calzetti et al. 2007Kennicutt & Moustakas 2007
HII regions galaxies (integrated fluxes)
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GALEX FUV + NUV (1500/2500 A)
IRAC 8.0 m MIPS 24 m
H + R
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M81
H + R
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M 81
24µm 70µm 160µm
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Bell 2003, ApJ, 586, 794
Radio Continuum Emission
• exploits tight observed relation between 1.4 GHz radio continuum (synchrotron) and FIR luminosity
• correlation may reflect CR particle injection/acceleration by supernova remnants, and thus scale with SFR
• no ab initio SFR calibration, bootstrapped from FIR calibration
• valuable method when no other tracer is available
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Cookbook
Extinction-Free Limit (Salpeter IMF, Z=ZSun)
SFR (Mo yr-1) = 1.4 x 10-28 L (1500) ergs/s/Hz
SFR (Mo yr-1) = 7.9 x 10-42 L (H) (ergs/s) Extinction-Dominated Limit; SF Dominated
SFR (Mo yr-1) = 4.5 x 10-44 L (FIR) (ergs/s)
SFR (Mo yr-1) = 5.5 x 10-29 L (1.4 GHz) (ergs/Hz)
Composite: SF Dominated Limit
SFR (Mo yr-1) = 7.9 x 10-42 [L H, obs + a L24m ] (erg s-1) [a = 0.15 – 0.31]
SFR (Mo yr-1) = 4.5 x 10-44 [L(UV) + L (FIR)] (ergs/s)
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General Points and Cautions• Different emission components trace distinct stellar
populations and ages– nebular emission lines and resolved 24 m dust sources trace ionizing
stellar population, with ages <5-10 Myr– UV starlight mainly traces “intermediate” age population, ages 10-200
Myr– diffuse dust emission and PAH emission trace same “intermediate”
age and older stars– 10 Myr to 10 Gyr(!)
• Consequence: it is important to match the SFR tracer to the application of interest– emission lines – Schmidt law, early SF phases– UV – time-averaged SFR and SFR in low surface brightness systems– dust emission – high optical depth regions
• Multiple tracers can constrain SF history, properties of starbursts, IMF, etc.
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Demographics of Local Star-Forming Galaxies and Starbursts
M82: Spitzer/CXO/HST
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• Spitzer Infrared Nearby Galaxies Survey (SINGS) – resolved UV radio mapping of 75 galaxies
– selection: maximize diversity in type, mass, IR/optical
• 11 Mpc H/Ultraviolet Survey (11HUGS)– resolved H, UV imaging, integrated/resolved IR of 400 galaxies
– selection: volume-complete within 11 Mpc (S-Irr)
• Survey for Ionization in Neutral-Gas Galaxies (SINGG)– resolved H, UV imaging, integrated/resolved IR of 500 galaxies
– selection: HI-complete in 3 redshift slices
• Integrated Measurements– Ha flux catalogue (+IR, UV) for >3000 galaxies within 150 Mpc
- integrated spectra (+IR, UV) for ~600 galaxies in same volume (Moustakas & Kennicutt 2006, 2007)
Primary Datasets
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Thanks to: S. Akiyama, J. Lee, C. Tremonti, J. Moustakas, C. Tremonti (Arizona), J. Funes (Vatican), S. Sakai (UCLA), L. van Zee (Indiana) + The SINGS Team: RCK, D. Calzetti, L. Armus, G. Bendo, C. Bot, J. Cannon, D. Dale, B. Draine, C. Engelbracht, K. Gordon, G. Helou, D. Hollenbach, T. Jarrett, S. Kendall, L. Kewley, C. Leitherer, A. Li, S. Malhotra, M. Meyer, E. Murphy, M. Regan, G. Rieke, M. Rieke, H. Roussel, K. Sheth, JD Smith, M. Thornley, F. Walter
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Spitzer Local Volume Legacy
• UV/H/IR census of local volume• HST ANGST sample to 3.5 Mpc• GALEX 11HUGS sampel to 11 Mpc
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The Starburst Bestiary
GEHRs
SSCs
HII galaxies
ELGs
CNELGs
W-R galaxies
BCGs
BCDs
LIGs, LIRGs
ULIGs, ULIRGs
LUVGs, UVLGs
nuclear starbursts
circumnuclear
starbursts
clumpy irregular
galaxies
Ly- galaxies
E+A galaxies
K+A galaxies
LBGs
DRGs
EROs
SCUBA galaxies
extreme starbursts
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Demographics of Star-Forming Galaxies
• absolute SFR (Mo/yr)– from H corrected for [NII], dust
• SFR density, intensity (Mo/yr/kpc2)– defined as SFR/R2
SF
– correlates strongly with gas density, SF timescale
• normalized SFR/mass; birthrate parameter b – ratio of present SFR to average past SFR– defined here globally – integrated over galaxy– primary evolutionary variable along Hubble sequence
Baseline: 11 Mpc H + Ultraviolet Survey (11HUGS) - all known galaxies w/gas within 11 Mpc + Ursa Major cluster - companion GALEX Legacy survey coming…
Quantify SF properties in terms of 3 observables:
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R = 100 pc
1 kpc
10 kpc
11HUGS/LVL Sample
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11HUGS Sample + HGS + Goldmine Virgo Sample (James et al. 2003; Gavazzi et al. 2003)
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Gronwall 1998
SFR* ~5 Mo/yr
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LIGs, ULIGs (Dopita et al., Soifer et al, Scoville et al)
merger-driven inflows, starbursts
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Martin 2005, ApJ, 619, L59
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Mgas/Hubble
gas/Hubble
Mgas/dyn
crit
1 O5V/3_Myr
0.5” @ 4 M
pc
Meurer limit
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Lecture 2 Ended Here Extra Slides Follow
(from Lecture 4)
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108 109 1010
1011 Mo
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11MPC + BCGs (Gil de Paz et al. 2003)
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11HUGS Sample + HGS + Goldmine Virgo Sample (James et al. 2003; Gavazzi et al. 2003)
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Disk SFRs: Main Results
• spectra best fitted with IMF ~ Salpeter for M* > 1 Mo
• SF is ubiquitous when cold gas is present - <4% S-Irr non-detects in H, nearly all show trace SF in UV
• average SFR/mass increases by 5-10x per type bin (S0 - Sa - Sb, etc)– proportional changes in disk SF history with type- changes in frequency and characteristic mass of SF events
• large residual variation in SFR within a given type– most variation in disk SFR vs B/D ratio– more strongly correlated with mean gas density– temporal SFR variations (bursts)
• strong bimodality seen in SFR/mass vs galaxy mass– extension to dwarfs shows evidence for third mode
• radial gradients in disk age and metallicity
Kennicutt 1998, ARAA, 36, 189Brinchmann et al. 2004, MNRAS, 351, 1151
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Disk Star Formation Rates and Histories
• evolutionary synthesis of integrated colors
Tinsley 1968, ApJ, 151, 547 Searle et al. 1973, ApJ, 179, 427 Larson, Tinsley 1978, ApJ, 219, 46
• results – disk colors consistent
with sequence of constant age, IMF, Z, and variable SF history (t)
– best fit for ~Salpeter IMF
– spectra fit with similar model sequence
Kennicutt 1983, ApJ, 272, 54
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Bruzual, Charlot 1993, ApJ, 405, 538
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Kennicutt 1992, ApJS, 79, 255
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Disk SF – Global Trends
Kennicutt 1998, ARAA, 36, 189 Bendo et al. 2002, AJ, 124, 1380
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Kennicutt, Tamblyn, Congdon 1994, ApJ, 435, 22
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Sandage 1986, A&A, 161, 89
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Kennicutt 1998, ARAA, 36, 189
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Bell, de Jong 2000,MNRAS, 312, 497
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• Gas consumption– typical timescales for
depletion ~few Gyr– stellar recycling of gas
is significant factor!
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SFR increase reflects an increase in frequency of SF events, and a shift in the mass spectrum of single events
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Brinchmann et al. 2004, MNRAS, 351, 1151
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blue sequence red sequence
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Kauffmann et al. 2003, MNRAS, 341, 54
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Lee & Kennicutt,in preparation
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Janice Lee, PhD thesis
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starburst duty cycle in dwarf galaxies (Lee 2006)
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see poster by Lee et al.
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Application to Starburst Duty Cycles
• bursts produce 20-40% of present-day SF in dwarfs• fraction of bursting dwarfs in same sample is 5-10%
• the galaxies are bursting 5-10% of the time
• average burst amplitude is ~4-8x the background SFR
• typical burst durations are 10-100 Myr (e.g., Gallagher, Harris, Calzetti, Zaritsky, Hunter…)
- a typical burst lasts for 0.1-1% of Hubble time
• a typical galaxy bursts ~10-20 times over a Hubble time, each time producing a few percent of its stars (every 500-1000 Myr)
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Disk SFRs: Main Results
• spectra best fitted with IMF ~ Salpeter for M* > 1 Mo
• SF is ubiquitous when cold gas is present - <4% S-Irr non-detects in H, nearly all show trace SF in UV
• average SFR/mass increases by 5-10x per type bin (S0 - Sa - Sb, etc)– proportional changes in disk SF history with type- changes in frequency and characteristic mass of SF events
• large residual variation in SFR within a given type– most variation in disk SFR vs B/D ratio– more strongly correlated with mean gas density– temporal SFR variations (bursts)
• strong bimodality seen in SFR/mass vs galaxy mass– extension to dwarfs shows evidence for third mode
• radial gradients in disk age and metallicity
Kennicutt 1998, ARAA, 36, 189Brinchmann et al. 2004, MNRAS, 351, 1151
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NGC 1512 (HST)
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NGC 1512 (GALEX FUV/NUV)
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Kormendy & Kennicutt 2004, ARAA, 42, 603 Sakamoto et al. 1999, ApJ, 525, 691
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M82NGC 3034
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Lo et al. 1987, ApJ, 312, 574
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Kennicutt 1998, ARAA, 36, 189
ELS limit
normal galaxies
IR-luminous galaxies
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Circumnuclear Star Formation - Trends with Type
Ho et al. 1997, ApJ, 487, 595
ellipticals too?!
Yi et al. 2005, ApJ, 619, L111
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Borne et al. 2000, ApJ, 529, L77
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IR-luminous: ~5-8%circumnuclear: ~3-4%BCGs, ELGs: ~5-8%
Contributions to the global star formation budget
Total fraction ~10-20%
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L’Floch et al. 2005, ApJ, 632, 169
total
IR-luminous starbursts