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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.

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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

Dale et al. 2007, ApJ, 655, 863


0.1 1 10 100 mag (AV)


GALEX FUV + NUV (1500/2500 A)

Ha + R

IRAC 8.0 mm

MIPS 24 mm


Spitzer Infrared Nearby Galaxies Survey (SINGS)

  • complete IRAC, MIPS imaging of 75 nearby galaxies (3.5 – 160 mm)

  • IRS, MIPS radial strip maps (10 – 100 mm)

  • IRS maps of centers, 75 extranuclear sources (5–37 mm)

  • 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


Building an Evolutionary Synthesis Model

+

Kurucz 1979, ApJS, 40, 1

single star SED evolution model

Maeder, Meynet 1988, A&AS, 76, 411


“single burst models” “continuous star formation” models

(single age star clusters)

Leitherer et al. 1999, ApJS, 123, 3 “Starburst99”


apply evolutionary synthesis maodels to constrain IMF

Kennicutt, Tamblyn, Congdon 1994, ApJ, 435, 22


UV, Dust, and Age

26

Starbursts

A dusty stellar population may have similar UV characteristics of an old population

(Calzetti et al. 1994,1995,1996,1997,2000,

Meurer et al. 1999, Goldader et al. 2002)


Blue= starbursts

Red= normal SF

26


M51Calzetti et al. 2005, ApJ, 633, 871

FUV,Ha, 24mm

3.6,4.5,5.8, 8.0mm


Photoionization Methods: Emission Lines

  • 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

SINGG survey, G. Meurer et al. (NOAO)


Kennicutt 1992, ApJS, 79, 255


Local Ha Surveys

Survey Ngal Selection PI

GOLDMine 277 magnitude Coma/VirgoG. Gavazzi

MOSAIC ~1000 HaAbell clustersR. Kennicutt

HaGS 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 isolatedfieldL. Montenegro

SINGS ***75 multi-param<30 Mpc R. Kennicutt

SMUDGES ~1000 mag field dwarfs L. van Zee

UCM 376 objprism field J. Gallego

KISS ~2200obj prismfield J. Salzer

** paired GALEX survey


Photoionization Methods: Emission Lines

  • 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

SINGG survey, G. Meurer et al. (NOAO)


Leakage of Ionizing Flux at z ~ 3

Shapley et al. 2006, ApJ, 651, 688


composite spectrum

Shapley et al. 2006, ApJ, 651, 688


galaxies (integrated fluxes)

HII regions

Calzetti et al., ApJ, submitted

Kennicutt & Moustakas, in prep


  • Other Emission Lines

    • - Hb (0.48 mm)

    • - Paschen-a (1.9 mm)

    • - Brackett-g (2.2 mm)

    • - [OII] (0.37 mm)

    • - Lyman-a (0.12 mm)

Scoville et al. 2000, AJ, 122, 3017


Wavelength


Moustakas, Kennicutt, Tremonti 2006, ApJ, 642, 775


Moustakas et al. 2006, ApJ, 642, 775


11 Mpc Ha/Ultraviolet Survey (11HUGS)

SINGG: Survey for Ionization in Neutral-Gas Galaxies

SINGG: Survey for Ionization in Neutral-Gas Galaxies

M83 = NGC 5236 (Sc)


Lecture 2 Begins Here


Dust Emission

  • Interstellar dust absorbs ~50% of starlight in galaxies, re-radiates in thermal infrared (3–1000 mm)

  • 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

`calorimetric’ IR

 (m) 1 10 100 1000

24 m

70 m

160 m

8 m

FIR - sensitive to heating from old stellar populations

8 m - mostly single photon heating (PAH emission)

24 m - both thermal and single photon heating

70 m and 160 m - mostly thermal, also from old stars


NGC 628

(M74)

C. Tremonti


Moustakas et al. 2006, ApJ, 642, 775


galaxies (integrated fluxes)

HII regions

Calzetti et al. 2007

Kennicutt & Moustakas 2007


GALEX FUV + NUV (1500/2500 A)

Ha + R

IRAC 8.0 mm

MIPS 24 mm


M81

Ha + R


M 81

24µm

70µm

160µm


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

Bell 2003, ApJ, 586, 794


Cookbook

Extinction-Free Limit(Salpeter IMF, Z=ZSun)

SFR (Mo yr-1) = 1.4 x 10-28 Ln (1500) ergs/s/Hz

SFR (Mo yr-1) = 7.9 x 10-42 L (Ha) (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 L24m ] (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 mm 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


Primary Datasets

  • Spitzer Infrared Nearby Galaxies Survey (SINGS)

    • resolved UV  radio mapping of 75 galaxies

    • selection: maximize diversity in type, mass, IR/optical

  • 11 Mpc Ha/Ultraviolet Survey (11HUGS)

    • resolved Ha, 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 Ha, 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)


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/Ha/IR census of local volume

    • HST ANGST sample to 3.5 Mpc

    • GALEX 11HUGS sampel to 11 Mpc


The Starburst Bestiary

nuclear starbursts

circumnuclear starbursts

clumpy irregular galaxies

Ly-a galaxies

E+A galaxies

K+A galaxies

LBGs

DRGs

EROs

SCUBA galaxies

extreme starbursts

GEHRs

SSCs

HII galaxies

ELGs

CNELGs

W-R galaxies

BCGs

BCDs

LIGs, LIRGs

ULIGs, ULIRGs

LUVGs, UVLGs


Demographics of Star-Forming Galaxies

Baseline: 11 Mpc Ha + 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:

  • absolute SFR (Mo/yr)

    • from Ha corrected for [NII], dust

  • SFR density, intensity (Mo/yr/kpc2)

    • defined as SFR/pR2SF

    • 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


11HUGS/LVL Sample

R = 100 pc

1 kpc

10 kpc


11HUGS Sample + HaGS + Goldmine Virgo Sample

(James et al. 2003; Gavazzi et al. 2003)


SFR* ~5 Mo/yr

Gronwall 1998


LIGs, ULIGs (Dopita et al., Soifer et al, Scoville et al)

merger-driven

inflows, starbursts


Martin 2005, ApJ, 619, L59


Mgas/tHubble

Mgas/tdyn

1 O5V/3_Myr

Meurer limit

0.5” @ 4 Mpc

Sgas/tHubble

Scrit


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 + HaGS + Goldmine Virgo Sample

(James et al. 2003; Gavazzi et al. 2003)


Disk SFRs: Main Results

Kennicutt 1998, ARAA, 36, 189

Brinchmann et al. 2004, MNRAS, 351, 1151

  • spectra best fitted with IMF ~ Salpeter for M* > 1 Mo

  • SF is ubiquitous when cold gas is present

    - <4% S-Irr non-detects in Ha, 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


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 y(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 sequencered 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

Kennicutt 1998, ARAA, 36, 189

Brinchmann et al. 2004, MNRAS, 351, 1151

  • spectra best fitted with IMF ~ Salpeter for M* > 1 Mo

  • SF is ubiquitous when cold gas is present

    - <4% S-Irr non-detects in Ha, 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


NGC 1512 (HST)


NGC 1512

(GALEX FUV/NUV)


Sakamoto et al. 1999, ApJ, 525, 691

Kormendy & Kennicutt 2004, ARAA, 42, 603


M82

NGC 3034


Lo et al. 1987, ApJ, 312, 574


IR-luminous galaxies

ELS limit

normal galaxies

Kennicutt 1998, ARAA, 36, 189


Circumnuclear Star Formation - Trends with Type

ellipticals too?!

Yi et al. 2005,

ApJ, 619, L111

Ho et al. 1997, ApJ, 487, 595


Borne et al. 2000, ApJ, 529, L77


Contributions to the global star formation budget

IR-luminous: ~5-8%

circumnuclear: ~3-4%

BCGs, ELGs: ~5-8%

Total fraction ~10-20%


total

IR-luminous

starbursts

L’Floch et al. 2005, ApJ, 632, 169


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