STARBURSTS IN PERSPECTIVE: The Multiwavelength View of Star-Forming Galaxies Robert Kennicutt U. Arizona U. Cambridge

Outline Introduction to starbursts –extreme starbursts? Clues from the local universe –Spitzer Infrared Nearby Galaxies Survey (SINGS)

Starbursts: Many Definitions Absolute star formation rate (SFR) much larger than the maximum in normal galaxies –at redshift z = 0 this implies SFR >> 10 M o /yr –comparable to luminous infrared galaxy (LIRG) (L IR > L o ) A large, centrally concentrated star formation event (R < 1 kpc) implies SFR surface density  sfr > 0.1 M o /yr/kpc 2 range in absolute SFR is large: 0.1 – 1000 M o /yr A star formation rate that is much higher than the average past SFR in the galaxy (b >> 1) A star formation rate that cannot be sustained by the galaxy’s gas supply for longer than 0.1 – 1 Gyr

11HUGS + H  GS + Goldmine (Virgo) H  Surveys (Kennicutt et al. 2005, James et al. 2003; Gavazzi et al. 2003) SFR area SFR

Starbursts: Milestones NGC 7714: “star-burst nucleus” Weedman et al. 1981, ApJ, 248, 105 –compact burst: ~10 M o /yr, R<<1 kpc IRAS, HST… infrared-luminous, ultraluminous galaxies SFRs ~ M o /yr, R = kpc uniquely identified with gas-rich galaxy mergers ISO Infrared spectra show decisively that LIRGs, ULIRGs are powered by combination of starbursts, AGNs Spitzer, GALEX, SCUBA Full spectral energy distributions (SEDs) of starbursts cosmic evolution of starbursts “unification” of IR-selected vs UV-selected primeval galaxies

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

Kennicutt 1998, ApJ, 498, 541 Gao, Solomon 2004, ApJ, 606, 271 Patterns, Scaling Laws normal galaxies starbursts

In the most luminous starburst galaxies the star formation is very compact (R < 1 kpc) and most energy is emitted in the infrared. Martin et al. 2005, ApJL, 619, L75 (GALEX Special Issue) Arp ULIRG

“Extreme” Starbursts(?) Several factors limit the maximum rate at which a galaxy can form stars –many starburst galaxies lie close to these limits “ELS” Limit (Eggen, Lynden-Bell, & Sandage; Heckman) –an absolute maximum SFR for a galaxy is set by its gas mass and dynamical time –SFR max = M gas / t dyn –for a massive galaxy: SFR lim ~ M o / 10 8 yr ~ 1000 M o /yr

Kennicutt 1998, ARAA, 36, 189, after Scoville et al ELS limit normal galaxies IR-luminous galaxies

Starburst Limits II Dust Radiation Pressure Limit (“dust Eddington limit”) (Murray, Quataert, & Thompson 2005, Downes & Solomon) –star formation rate is limited by radiation pressure on dust grains, which can disperse the gas disk –may explain origin of Faber- Jackson and black hole mass vs galaxy mass/dispersion relations –Predicts limiting SFR intensity, ~1000 M o /yr/kpc 2

1000 M o /yr Murray et al. 2005

Starburst Limits III Large-Scale Mass Loss, Galactic Superwinds (e.g., Dekel & Silk, Heckman, Martin) –clustered stellar winds and supernovae produce “superwind” that may eject gas and metals from galaxy –winds will terminate starburst, and possibly end star formation altogether –effects especially pronounced in dwarf galaxies with shallow potential wells, but mass loss seen on all galaxy mass scales

NGC 1569: Chandra + Ha M82 BVR + Ha + [NII] + [SII] Martin et al. 2002, ApJ, 574, 663 M. Westmoquette et al., NOAO

Clues from Nearby (Normal) Galaxies star formation diagnostics –test, calibrate SFR measurements in UV, visible, IR, radio –reference libraries of galaxy SEDs, spectra –reference data on star formation at z = 0 spatially-resolved studies -structure of different IR-emitting components -dust radiative transfer (UV, optical extinction, dust heating) -structure, topology of ISM underlying physics of large-scale star formation - SFR vs gas density (Schmidt) law, other scaling laws - impact of star formation on surrounding ISM - variations in clustering, populations, IMF, etc.

An Information Explosion advent of the mega-survey –SDSS, 2DF --> imaging, spectra for >>10 6 galaxies to z=0.2 GALEX –SFRs for 10 7 galaxies at z<1, 10 4 galaxies within 70 Mpc –dedicated surveys (MIS/DIS, GANGS, SUNGG, 11MPC) Spitzer –3 Legacy surveys + MIPS/IRS GTO starburst survey H  surveys –UCM, KISS, AMIGA, GoldMine, H  GS, Mosaic Cluster, SINGG, SMUDGES, 11Mpc+ ---> >4000 galaxies, public data for most ISM surveys –e.g., WHISP, THINGS, BIMA SONG --> ALMA, Herschel True multi-wavelength surveys (e.g., SINGS, SWIRE)

Thanks to: The 11HUGS Team: C. Tremonti, J. Lee, J. Moustakas, S. Akiyama J. Funes (Arizona), S. Sakai (UCLA), L. van Zee (Indiana) + The SINGS Team: RCK, D. Calzetti, L. Armus, G. Bendo, B. Buckalew, J. Cannon, D. Dale, B. Draine, C. Engelbracht, K. Gordon, G. Helou, D. Hollenbach, T. Jarrett, L. Kewley, C. Leitherer, A. Li, S. Malhotra, M. Meyer, E. Murphy, M. Prescott, M. Regan, G. Rieke, M. Rieke, H. Roussel, K. Sheth, JD Smith, M. Thornley, F. Walter + 10 babies!

11 Mpc H  and Ultraviolet Survey (11HUGS) H  imaging for 400 spiral-irregular galaxies within 11 Mpc of Milky Way (complete for b > 20 o, B < 15) GALEX UV imaging (Cycle 1 Legacy project + archival data) for 284/400 galaxies drift-scan integrated spectra for ~200 galaxies Science goals –SFR statistics, demographics for a volume-limited sample –the SFR burst duty cycle in dwarf galaxies (Janice Lee) –evolution/migration of star formation within galaxies –SFR metrics, reference for cluster, lookback studies –HII region/cluster statistics, atlas –an archival resource for the astronomical community

> 11 Mpc H  /Ultraviolet Survey (11HUGS) Distribution of Specific SFRs U9240 UA106 M81 U7559 Cen A N7090 Sex A N4826 M83 N3432 N4449 GR8 IC4662 U681

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 (5–37  m) ancillary dataset covering UV to radio

Ferguson et al 1998, ApJ, 506, L19 MIPS 24  m NGC 6946 H  vs IR Spitzer maps the 40% of the bolometric energy of nearby galaxies emitted in the mid- to far-infrared..

0.15  m  m  m 3.6  m 8.0  m 24  m 70  m 160  m

GALEX FUV + NUV (1500/2500 A) IRAC 8.0  m MIPS 24  m H  + R

SINGS Science Highlights structure of the dusty ISM in galaxies (pretty pictures) star formation rate diagnostics –global SEDs of galaxies –infrared SFR tracers for high-z galaxies extinction and evolution of massive SF regions the star formation – gas density (Schmidt) law

NGC 4594

8  m

M82 = NGC  m

M82 = NGC  m

(P  region, d~6 kpc Scoville et al. 2001)

M81 H  + R

Kennicutt et al, in preparation 24  m + Ha SFRs Calzetti et al 2005, ApJ, in press

Integrated SEDs of SINGS galaxies Dale et al. 2005, ApJ, submitted

Dale et al., 2005, ApJ, in press

8  m SFRs Dale et al., 2005, ApJ, in press Metal-rich galaxies have a limited dispersion in 8  m/FIR ratio (within a factor ~10), but the dispersion increases (~20x) when adding metal-poor objects.

B = UIT FUV G = IRAC 8  m R = MIPS 24  m M101: Gordon et al., in prep (MIPS GTO team)

Kennicutt 1998, ApJ, 498, 541 The SFR vs Gas Density Law (Schmidt Law) observations show a strong correlation between the disk- averaged star formation rate (SFR) and the mean gas density of the disk a single power law of slope N ~ 1.4 fits the full range of galaxy types, from normal disks to ultraluminous infrared starburst galaxies does this global relation also apply locally within galaxies?

Kennicutt et al., in preparation Kennicutt 1998, ApJ, 498, 541

Local Schmidt Law Kennicutt, Calzetti, Walter, et al. 2005, in prep. slope= 1.41

Whole galaxies Kennicutt et al. 2005, in prep. Schmidt Law…

SINGS Legacy Data Products Full-coverage IRAC + MIPS imaging (  m) Radial IRS + MIPS SED datacubes (  m) Spectral maps of galaxy centers + 75 extra-nuclear IR-emitting regions (  m) Ancillary data –BVRIJHK, Ha, P , HI, CO, submm, radio cont, UV –ancillary optical spectra (nuclear, centers, SED strips) –pixel-resolved SED library of galaxies (  m) Data analysis tools (SEDTOOL, Cubism, CubeView) 25 galaxies/delivery: May 2005 – May 2006

SINGS Homepage: SINGS Pipeline Data: SINGS Data Products: SINGS Observations Kennicutt et al. 2003, PASP, 115, 928