background slides from lecture 1

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