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Collisional ISM Heating in Ellipticals: the Case of M86

Collisional ISM Heating in Ellipticals: the Case of M86. Jeffrey Kenney (Yale) Tomer Tal (Yale) Hugh Crowl (Yale) John Feldmeier (YSU) George Jacoby (WIYN). SDSS gri. SDSS gri KPNO MOSAIC H  +[NII]. NGC 4438. M86. Separation 23’ = 115 kpc. Kenney etal 2008. H  velocities from

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Collisional ISM Heating in Ellipticals: the Case of M86

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  1. Collisional ISM Heating in Ellipticals: the Case of M86 Jeffrey Kenney (Yale) Tomer Tal (Yale) Hugh Crowl (Yale) John Feldmeier (YSU) George Jacoby (WIYN)

  2. SDSS gri

  3. SDSS gri KPNO MOSAIC H+[NII]

  4. NGC 4438 M86 Separation 23’ = 115 kpc Kenney etal 2008

  5. H velocities from WIYN Sparsepak

  6. X-ray (ROSAT) HI (VLA) H(KPNO 4m)

  7. H B NGC 4438 (Arp120) • very HI-deficient <10% “normal” HI • ~5x109 Msun of HI “missing” HI on B X-Ray on H X-ray: Machacek etal 2004 HI: Hota etal 2007

  8. M86 X-ray (Chandra: Randall etal 2008) HI (VLA: Li & van Gorkom 2001) H M(HI) = 2x108 Msun

  9. Collisional KE should be significant heating source for M86 ISM • Kinetic energy of gas stripped from NGC 4438 by gaseous halo of M86 1/2Mv2 = 1/2 (5x109Msun)(1000 km/s)2 = 5x1058 erg compare to: • Thermal energy of M86 ISM nkTV = (10-3 cm-3)(0.8 keV)(4/3)(73 kpc)3 = 6x1058 erg

  10. H evidence for a previously unknown high-velocity collision between M86 and highly disturbed spiral NGC 4438 (during subcluster merger) • HI stripped from NGC 4438 by ram pressure during passage through M86 ISM leaves debris trail of gas heated by ram pressure drag /collisional excitation/shocks/thermal conduction (?) from hot ISM of M86, producing H filaments

  11. Relevant for current major problem in galaxy formation/evolution: how to prevent continued star formation and stellar growth of largest galaxies • Large collision KE~1059 erg from stripped gas should contribute to heating of M86 ISM, inhibiting “cooling flow”, star formation and BH fueling • M86 has very weak radio source, so AGN heating of ISM unlikely at present • Although extreme case, ISM easy to study in M86: should teach us about general importance of gravitational ISM heating in ellipticals

  12. Kenney etal 2008

  13. A 3rd galaxy involved?HI tail from NGC 4388(Oosterloo & van Gorkom 2005) High velocity (2000-2500 km/s) HI (WRST) and H tail from NGC 4388 (contours, green) Low velocity (-600 to +100 km/s) H between M86 and NGC 4438 (red)

  14. Implication for EVLA • Some galaxies/clusters have very large range of velocities, which cannot be observed with VLA correlator • But CAN BE with EVLA correlator

  15. Chandra X-ray Randall etal 2008

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