An Evolutionary Model of Submillimeter Galaxies

Sukanya Chakrabarti

NSF Fellow

CFA

Merging Galaxies, Starbursts

Mergers Dusty, Infrared Bright Galaxies ULIRGs – LIR > 1012 Lsun

•Toomre & Toomre (1972): “Galactic collisions can bring deepinto a galaxy a fairly sudden supplyof interstellar material” •Hydrodynamic simulations – Mihos & Hernquist (1996) – galactic bridges & tails, starbursts

Sanders & Mirabel (1996)

Merging Galaxies, Starbursts & AGN

(fast-forwarding a few years…)

Chandra image of NGC 6240: (Komossa et al 03) Recent Hydrodynamical

Simulations with Black Holes: Springel et al. 2005

Submillimeter Galaxies• Massive galaxies, with SFR of

~500-1000 Msun/yr. Sub-mm SCUBA surveys in late 90s (Smail et al 2000, Ivison et al. 98).

• SMGs: F850 > 1 mJy. Spectroscopic redshifts for higher redshift population (z~2), median F850 ~ few mJy for z~2 population.

• Before Spitzer and SHARC-2 observations (Kovacs et al. 2006), mostly 850 micron, some 450 micron, radio observations, CO, and some mm imaging.

• X-ray observations - Alexander et al. (2005) – AGN in SMGs. Total contribution of AGN to luminosity not known.

SMM J02399-0136 (Genzel et al 03)

How I study Dusty Galaxies (Feedback DrivenMethod of Study)

Simulations of Galaxy Mergers

Compare to observations - refine and calibratemodels

Radiative TransferCalculations (RADISH): Images,SED template factory, 6 panel moviesInfrared, CO (D. Narayanan), Lyman continuum, Lyman-alpha

Outline of Talk

•Simulations with AGN Feedback and starburst feedback for local LIRGS & ULIRGs - evolution of far-IR SEDs. Cold-Warm IRAS classification.•General trends: do these two kinds of feedback affect the evolutionary history differently?

•Submillimeter Galaxies at z ~ 2: Photometric Properties: IRAC color-color plot•What is the Role of AGN in SMGs: Infrared X-ray correlationsPhoto Albums of SMGs during their lifetimes•Classfication & Evolutionary Scheme for SMGs

•Star Formation in Recent High Resolution Simulations of Quiescent Galaxies

Basics of Radiative Transfer

•Contribution functions & SEDs from Chakrabarti & McKee 2005•L/M and Source of illumination does not matter for reprocessed far-IR SED

•What does self-consistent RT calculation mean: div F =0 -> Radiative Equilibrium.

Low

Intermediate High

temperature

Optical depth

AGN

dzyxTJdzyxTB )],,([)],,([

Temperature: Radiative Equilibrium

UnresolvedSources

ResolvedSources

RADISH: Photons that emerge undergo: attenuation,scattering, reemission

Chakrabarti & Whitney 2007

General Trends: Cold-Warm Transition: Telling AGN & Starbursts Apart

•AGN feedback:disperses gasmore effectively – lowercolumns – more highfrequency flux at peak of luminosity.•Source of illumination irrelevant•F(25)/F(60) increases with mass loading efficiency of starburst winds. Chakrabarti, Cox, et al. 2007a (and in Spitzer’s MIPS & Herschel’s PACS),SB winds - Cox,Chakrabarti,et al.2007

solid line: AGN feedback. Dotted: =0.5, dashed: =0.05,dash dotted: =0.005 (focus on typical observed values (Martin 05,06,Rupke et al 05)

Predictions for Herschel: Cold –Warm Trend: Telling AGN & Starbursts Apart

From Chakrabarti et al. 2007a

IRAC color-color plot

Lacy et al. (2004) from Spitzer FLS. Dashed lines mark “AGN-demarcated region”

Hot dust

Bunny-ear shape

clustering

IRAC color-color plots

• What is the clustering in the color-color plot due to? (Chakrabarti et al. 2006b)

clustering

AGN demarcated

region

Unfolding IRAC color-color plots

• Clustering in color-color plots – correlated with time spent in region of color space and stars dominating in bolometric luminosity output.

Clustering: time

Clustering: stars

Hot dust: LBH > Lstar

IRAC color-color plot

RAC color-color plot in rest-frame RAC color-color plot for z=0.3 slice,bunny- ear shape.

Bunny-ear shape

clustering

Hot dust

Life of A Sub-mm Galaxy: Time

Towards An Evolutionary Scheme for SMGs

Chakrabarti et al. 2007b. SMG phase short-lived: Class I,II only, dust emission ~10 kpc

Transition from Class I -> Class II : SEDs of SMGscold warm

SED Fit to SMG data of z~1 galaxy inPope et al. 2006. Close to Class I phase,With BH ~ 40 % of L, SFR ~ 500 Msun/yr

SED Fit to SMG data of z~2galaxy in Pope et. al 2006.Close to Class II phase, with BH ~ 80 % of L, SFR ~ 300 Msun/yr

If you have any (radiative) transfer problems …

Please call:

1-800-RADISH

Future Directions• Interfacing Simulations & Multiwavelength

Observations to understand galaxy evolution: Future Space Missions: Herschel Space Observatory & JWST.

•High Resolution Simulations of Mergers Kazantzidis, Mayer (~few pc)•Physical Models of AGN Feedback (Ciotti & Ostriker 07)•High Resolution Simulations of Spiral Galaxies: how does spiral structure arise? Why does it persist? How does it affect star formation?