Spitzer Observations of Hickson Compact Groups of Galaxies

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<m 1+3 mag – Isolation: Rneighbor>3 Rgroup – Compactness: G<26 mag/arcsec 2 – (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 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 Brent Groves, Radio --->2005

Spitzer IRAC & MIPS Mid-IR Imaging 3. 6 m 4. 5 m Mostly Stars, some PAHs Just Stars 5. 8 m Some Stars, mostly PAHs 8 m PAHs J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 24 m Hot dust

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 Nearb y gala Compact groups J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 xies Virgo core Huchtmeier 1997

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

HI Deficiency: HI properties of 324 isolated galaxies: Haynes & Giovanelli, 1984 Def. HI = 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~2 x 1010 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

HCG 61 (N=3) R-band Not HI Def Halpha X Vilchez & Iglesias-Paramo 1998 IRAC 24 um Log Lx<41. 6 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005

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

HCG 22 (N=3) Optical+HI Def. HI=0. 59 A C B X X E ATCA Archive, thanks to B. Koribalski D A=d. Sy 2 IRAC 24 um J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 * ROSAT (Log Lx=40. 6) Mulchaey et al. 2003

HCG 07 (N=4) R-band Halpha IRAC+HI Def. HI=0. 64 * Vilchez & Iglesias-Paramo 1998 * * * VLA Archive IRAC 24 um 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

HCG 16 (N=4+2) R-band Optical+HI Def. HI=0. 41 Halpha * Vilchez & Iglesias-Paramo 1998 IRAC ** Verdes-Montenegro 2001 24 um B=Sy 2 XMM A=LNR C=SBNG D=LNR J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 Log Lx=41. 0

HCG 31 (N=4+2) R-band Optical+HI Halpha * Vilchez & Iglesias-Paramo 1998 IRAC 24 um Verdes-Montenegro 2001 Def. HI=0. 57 Log Lx<41. 2 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005

• 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) Def. HI=1. 4 A=Sy 2 IRAC B � A � C � D � Optical+HI * * ROSAT D=LNR J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 Log Lx=40. 8 Mulchaey et al. 2003

HCG 42 (N=4) IRAC E dominated C � ROSAT A � B � D � 24 um A=d. LNR 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 B � C � A � D � Log Lx=42. 9 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 HCG 7 C: Def=0. 55 PAHs HCG 7 D Def=0. 55 PAHs + warm dust J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 HCG 7 B Def>1. 3 HCG 7 A Def=0. 85

[3. 6]-[4. 5] (mag) Trends with MIR Colors Blue=not HI Def Red=HI Def AGN 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 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5 -9 2005 HCG 90 D Def. HI>2. 0

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