Collisional ISM Heating in Ellipticals: the Case of M86 Jeffrey

15 Slides2.40 MB

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


NGC 4438 M86 Separation 23’ 115 kpc Kenney etal 2008

H velocities from WIYN Sparsepak

X-ray (ROSAT) HI (VLA) H (KPNO 4m)

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

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

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

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

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

Kenney etal 2008

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)

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

Chandra X-ray Randall etal 2008

Related Articles

Back to top button