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
Background Slides from Lecture 1
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
0.1 1 10 100 mag (AV)
GALEX FUV + NUV (1500/2500 A)
IRAC 8.0 m MIPS 24 m
H + R
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
UV Continuum Emission
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
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
Steidel et al. 1996, ApJ, 462, L17
Maeder, Meynet 1988, A&AS, 76, 411
Building an Evolutionary Synthesis Model
Kurucz 1979, ApJS, 40, 1
+
single star SED evolution model
Leitherer et al. 1999, ApJS, 123, 3 “Starburst99”
“single burst models” “continuous star formation” models (single age star clusters)
apply evolutionary synthesis maodels to constrain IMF
Kennicutt, Tamblyn, Congdon 1994, ApJ, 435, 22
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
26
Blue= starburstsRed= normal SF
M51 Calzetti et al. 2005, ApJ, 633, 871
FUV, H, 24m 3.6, 4.5, 5.8, 8.0 m
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
Kennicutt 1992, ApJS, 79, 255
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
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
Leakage of Ionizing Flux at z ~ 3
Shapley et al. 2006, ApJ, 651, 688
Shapley et al. 2006, ApJ, 651, 688
composite spectrum
Calzetti et al., ApJ, submittedKennicutt & Moustakas, in prep
HII regions galaxies (integrated fluxes)
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
Wavelength
Moustakas, Kennicutt, Tremonti 2006, ApJ, 642, 775
Moustakas et al. 2006, ApJ, 642, 775
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)
Lecture 2 Begins Here
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
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
NGC 628(M74)
C. Tremonti
Moustakas et al. 2006, ApJ, 642, 775
Calzetti et al. 2007Kennicutt & Moustakas 2007
HII regions galaxies (integrated fluxes)
GALEX FUV + NUV (1500/2500 A)
IRAC 8.0 m MIPS 24 m
H + R
M81
H + R
M 81
24µm 70µm 160µm
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
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)
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.
Demographics of Local Star-Forming Galaxies and Starbursts
M82: Spitzer/CXO/HST
• 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
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
Spitzer Local Volume Legacy
• UV/H/IR census of local volume• HST ANGST sample to 3.5 Mpc• GALEX 11HUGS sampel to 11 Mpc
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
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:
R = 100 pc
1 kpc
10 kpc
11HUGS/LVL Sample
11HUGS Sample + HGS + Goldmine Virgo Sample (James et al. 2003; Gavazzi et al. 2003)
Gronwall 1998
SFR* ~5 Mo/yr
LIGs, ULIGs (Dopita et al., Soifer et al, Scoville et al)
merger-driven inflows, starbursts
Martin 2005, ApJ, 619, L59
Mgas/Hubble
gas/Hubble
Mgas/dyn
crit
1 O5V/3_Myr
0.5” @ 4 M
pc
Meurer limit
Lecture 2 Ended Here Extra Slides Follow
(from Lecture 4)
108 109 1010
1011 Mo
11MPC + BCGs (Gil de Paz et al. 2003)
11HUGS Sample + HGS + Goldmine Virgo Sample (James et al. 2003; Gavazzi et al. 2003)
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
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
Bruzual, Charlot 1993, ApJ, 405, 538
Kennicutt 1992, ApJS, 79, 255
Disk SF – Global Trends
Kennicutt 1998, ARAA, 36, 189 Bendo et al. 2002, AJ, 124, 1380
Kennicutt, Tamblyn, Congdon 1994, ApJ, 435, 22
Sandage 1986, A&A, 161, 89
Kennicutt 1998, ARAA, 36, 189
Bell, de Jong 2000,MNRAS, 312, 497
• Gas consumption– typical timescales for
depletion ~few Gyr– stellar recycling of gas
is significant factor!
SFR increase reflects an increase in frequency of SF events, and a shift in the mass spectrum of single events
Brinchmann et al. 2004, MNRAS, 351, 1151
blue sequence red sequence
Kauffmann et al. 2003, MNRAS, 341, 54
Lee & Kennicutt,in preparation
Janice Lee, PhD thesis
starburst duty cycle in dwarf galaxies (Lee 2006)
see poster by Lee et al.
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)
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
NGC 1512 (HST)
NGC 1512 (GALEX FUV/NUV)
Kormendy & Kennicutt 2004, ARAA, 42, 603 Sakamoto et al. 1999, ApJ, 525, 691
M82NGC 3034
Lo et al. 1987, ApJ, 312, 574
Kennicutt 1998, ARAA, 36, 189
ELS limit
normal galaxies
IR-luminous galaxies
Circumnuclear Star Formation - Trends with Type
Ho et al. 1997, ApJ, 487, 595
ellipticals too?!
Yi et al. 2005, ApJ, 619, L111
Borne et al. 2000, ApJ, 529, L77
IR-luminous: ~5-8%circumnuclear: ~3-4%BCGs, ELGs: ~5-8%
Contributions to the global star formation budget
Total fraction ~10-20%
L’Floch et al. 2005, ApJ, 632, 169
total
IR-luminous starbursts