Spitzer Observations of Hickson Compact Groups of Galaxies J. E. Hibbard (NRAO), K. Johnson (P.I., UVa), A. Heiderman (NRAO REU), S. C. Gallagher, K. C. Peterson (UCLA), A. E. Hornschemeier (GSFC) & J. C. Charlton (PSU), J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Compact Groups: Hickson 1982 Richness: N>3 with m<m1+3mag Isolation: Rneighbor>3Rgroup Compactness: G<26 mag/arcsec2 (selected off of red plates, so bias towards early types) May be stage in evolution to cluster core, field early type, or “fossil group”, or “dry merger remnants” (c.f. yesterdays talk by Emanuela Pompei) Stay tuned to meeting - 6 more CG talks on schedule! J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Spitzer Survey of HCGs: Kelsey Johnson (UVa) P.I. IRAC and MIPS imaging of 12 close HCGs spanning a range of evolutionary states Use MIR to conduct a complete census of activity (AGN; star formation) and dust content of HCGs This is VERY MUCH a work in progress! (some photometry completed yesterday). See Kelsey’s presentation & Amanda’s poster at January AAS (Washington D.C) for actual results! J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Spitzer IRAC 3.6, 4.5, 5.8, 8 m bands + MIPS 24m Starburst SED Models Spitzer Dust Stars 3.6m 8m 24m Radio ---> Brent Groves, 2005 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Spitzer IRAC & MIPS Mid-IR Imaging Mostly Stars, some PAHs Just Stars 5.8 m 8 m 24 m Some Stars, mostly PAHs PAHs Hot dust J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

So whats a nice radio astronomer like me involved for? Compact groups are deficient in HI with respect to field galaxies of the same type Nearby galaxies Virgo Compact groups Virgo core Huchtmeier 1997 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Verdes-Montenegro et al. 2001 Compact groups Virgo Coma Coma I group J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

HI Deficiency: DefHI = log[ M(HI:L)pred ] - log[ M(HI:L)obs ] HI properties of 324 isolated galaxies: Haynes & Giovanelli, 1984 DefHI = log[ M(HI:L)pred ] - log[ M(HI:L)obs ] (positive for systems more deficient than isolated galaxies of same type) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Evaluate evolution of HCGs, especially with respect to their cold gas content and proposed evolutionary scenario (L. Verdes-Montenegro, 2001) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Can this help us understand “quenching” of star formation in massive galaxies?? J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

In models, continued infall slows color evolution of remnants (Somerville 2005) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

SAMs can reproduce observed bimodality by truncating SF when bulge gets above some critical value Mcrit~2x1010 Mo (Somerville 2005) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Spitzer IRAC 3.6m, 4.5m, 5.0m, 8.0m color images J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Phase 1: HI in individual galaxies. HCG 02 HCG 61 HCG 59 HCG 19* HCG 22* HCG 07** *=at least one member HIdef **=all members HIdef (L. Verdes-Montenegro, 2001) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Vilchez & Iglesias-Paramo 1998 HCG 61 (N=3) Not HI Def R-band Halpha X Vilchez & Iglesias-Paramo 1998 24um IRAC Log Lx<41.6 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

* HCG 19 (N=3+2) Not HI Def Optical+HI Optical X No X-ray IRAC 24um C B * X D VLA Archive No X-ray IRAC 24um J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

* HCG 22 (N=3) DefHI=0.59 Optical Optical+HI X X ROSAT (Log Lx=40.6) B X X E ATCA Archive, thanks to B. Koribalski D ROSAT A=dSy2 (Log Lx=40.6) IRAC 24um J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005 Mulchaey et al. 2003

Vilchez & Iglesias-Paramo 1998 HCG 07 (N=4) DefHI=0.64 R-band Halpha IRAC+HI * * * * Vilchez & Iglesias-Paramo 1998 VLA Archive 24um IRAC Log Lx<41.7 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Phase 2: HI being tidal removed from galaxies. HCG 31** HCG 16** *=at least one member HIdef **=all members HIdef (L. Verdes-Montenegro, 2001) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Vilchez & Iglesias-Paramo 1998 HCG 16 (N=4+2) DefHI=0.41 Optical+HI R-band Halpha * * * Vilchez & Iglesias-Paramo 1998 Verdes-Montenegro 2001 24um XMM IRAC B=Sy2 A=LNR C=SBNG D=LNR Log Lx=41.0 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Vilchez & Iglesias-Paramo 1998 HCG 31 (N=4+2) Optical+HI R-band Halpha * Vilchez & Iglesias-Paramo 1998 Verdes-Montenegro 2001 DefHI=0.57 24um IRAC Log Lx<41.2 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

(L. Verdes-Montenegro, 2001) Phase 4: X-ray medium. no HI in central galaxies; deficient galaxies in the outskirts HCG 48? HCG 90** HCG 62? ?=no HI map **=all members HIdef (L. Verdes-Montenegro, 2001) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

* * HCG 90 (N=4+1) DefHI=1.4 IRAC Optical+HI ROSAT Log Lx=40.8 A B A=Sy2 IRAC A Optical+HI * B C * D ROSAT Log Lx=40.8 D=LNR Mulchaey et al. 2003 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

HCG 42 (N=4) E dominated IRAC ROSAT 24um Log Lx=41.8 C A B D A=dLNR Log Lx=41.8 Mulchaey et al. 2003 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

HCG 62 (N=4) E dominated Chandra IRAC Log Lx=42.9 B C A D J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

So what can we do with the MIR data? SEDs give dominant activity Spatially separate SED J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Def vs. MIR SEDs Stars HCG7C: Def=0.55 PAHs HCG7D Def=0.55 HCG7B Tidal interactions create or disrupt star formation (vm) HCG7A Def=0.85 PAHs + warm dust J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Trends with MIR Colors Blue=not HI Def Red=HI Def [3.6]-[4.5] (mag) AGN [3.6]-[4.5] (mag) PAHs stars [4.5]-[8.0] (mag) J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Nuclear vs. Extranuclear MIR SEDs HCG 90 PAHs & Hot dust Mostly starlight HCG 90D DefHI>2.0 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

Conclusions: None yet. But track down Kelsey or Amanda Heiderman at January AAS Meeting J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005