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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),. Compact Groups:. Hickson 1982 Richness: N>3 with m<m 1 +3mag

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Spitzer Observations of Hickson Compact Groups of Galaxies

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  1. 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

  2. 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

  3. 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

  4. Spitzer IRAC 3.6, 4.5, 5.8, 8 m bands+ MIPS 24m Starburst SED Models Spitzer Dust Stars 3.6m 8m24m Radio ---> Brent Groves, 2005 J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

  5. Spitzer IRAC & MIPS Mid-IR Imaging 3.6 m 4.5 m 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

  6. 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

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

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

  9. 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

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

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

  12. 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

  13. 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

  14. 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

  15. Not HI Def HCG 61 (N=3) 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

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

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

  18. 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

  19. 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

  20. 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

  21. Optical+HI HCG 31 (N=4+2) 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

  22. 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

  23. HCG 90 (N=4+1) DefHI=1.4 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

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

  25. 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

  26. 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

  27. Def vs. MIR SEDs Stars HCG7C: Def=0.55 PAHs HCG7D Def=0.55 HCG7B Def>1.3 HCG7A Def=0.85 PAHs + warm dust J. Hibbard ESO Workshop: Groups of Galaxies Dec 5-9 2005

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

  29. 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

  30. 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

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