The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Cool Cores in Galaxy Groups Ewan O’Sullivan Harvard-Smithsonian Center for Astrophysics In Collaboration with T. J. Ponman (University of Birmingham), J. Vrtilek & L. P. David (CfA), A. J. R. Sanderson (University of Illinois)

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Introduction  The majority of galaxies in the universe are found in galaxy groups (Tully 1987), and many elliptical- dominated groups have massive hot gas halos (Mulchaey 2003).  A general X-ray study of galaxy groups with Chandra and XMM-Newton (and ROSAT), focusing particularly on cooling and feedback processes Questions  It is now clear that AGN heating stops cooling flows in clusters - is this also true in groups?  How does group gas become enriched with metals?

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Groups Sample 23 groups from XMM archive, 18 from Chandra

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Analysis 2-D multi-component surface brightness fits Radial spectral profiles (circular or elliptical, deprojected)  Derive mass, entropy, cooling time, etc. profiles, assuming hydrostatic equilibrium  What about disturbed systems? Adaptively binned spectral maps - each pixel represents a separate spectral fit, but fits are not independent. Behaviour comparable to adaptive smoothing Current focus on XMM data, work in progress!

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 NGC 5044 From ROSAT (David et al 1994)  Cooling flow (20 M  /yr)  Cooling wake indicates ~100 km/s motion of galaxy From Chandra / XMM: No CF, no gas kT<0.6 keV (Tamura et al 2003; Buote et al 2003) Our XMM analysis: No CF, but cooling time less than 10 9 yrs Minimal AGN activity, so what prevents cooling? Is cooling wake seen? Deprojected temperature Deprojected abundance Gas cooling time

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Cooling wake XMM X-ray image with optical contours Temperature map

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 NGC 4636 Jones et al (2002) use Chandra to find ‘spiral arms’ in core  Shocks from AGN outburst? Ohto et al (2003) find high kT, excess N H west of core  Cavity blown by AGN jets during previous outburst? Chandra image with VLA-First contours

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Cavity to E clearly visible SW ‘Spiral arm’ marks cavity boundary Highest abundance gas outside galaxy core? Complex spectra… Chandra image XMM temperature XMM abundance

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 NGC 4636 spectral maps Hot gas surrounds core on N and E sides Highest abundances to SW XMM TemperatureXMM Abundance

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 NGC 4636 southwest region Plume of cool gas to SW with high abundance AGN driving galaxy/group gas mixing? XMM TemperatureXMM Abundance

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 NGC 507 ROSAT shows strong cooling in core (Kim & Fabbiano 1995) FR-I radio galaxy (Parma et al 1986) Paolillo et al (2003) find X-ray / radio structure correlated but no CF AGN power sufficient to stop cooling Kraft et al (2004) find abundance edge NE of core

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 XMM temperature XMM abundance XMM gaussian smoothed DSS optical

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Bright groups comparison Comparable M total, M gas profiles Large difference in kT, central density, Entropy NGC 507 AGN most active, NGC 4636 activity beginning AGN cycle governs core entropy?

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 AWM 4 & MKW 4: poor clusters ~2.5 keV systems chosen to be regular, undisturbed Very large central dominant galaxies NGC 4073 in MKW4 is radio quiet NGC 6051 in AWM4 has 100 kpc radio jets

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 AWM 4 kT and abundance clearly affected by AGN activity - cavity to E, shock and high abundance to NW Relaxed system, SB profile well described by two  -models Isothermal kT profile XMM temperature XMM abundance

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 MKW 4 Maps show highest abundances in core and to SE, where SB profile shows steepest drop SB fits show cluster is asymmetrical Strong kT drop in core but no gas <0.5 keV XMM abundance XMM temperature

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 MKW 4 / AWM 4 comparison Very similar mass profiles MKW4 has cooler, denser, more gas-rich core  Rapid cooling Gas fraction step in AWM 4  Gas pushed out by AGN

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 AWM 4 / MKW 4 summary Slight difference in core M total caused by difference in BCG mass (factor ~2) Remaining differences caused by AGN cycle - AWM 4 isothermal because of AGN heating - MKW 4 is cooling, soon to trigger AGN? Current radio power in AWM 4 ~10 41 erg/s, but expect mechanical power to be up to 10 4 times greater Energy required to raise MKW 4 temperature to that of AWM 4: ~9x10 58 erg or ~3x10 43 erg/s for 100 Myr - reasonable for AGN

The Environments of Galaxies: from Kiloparsecs to Megaparsecs August 2004 Conclusions  Cooling Flow / AGN connection holds across wide range of mass scales (1 keV groups to massive clusters)  Enrichment of groups through AGN galaxy / group gas mixing likely (at least in central regions)  AGN outbursts probably a major source of energy feedback in groups as well as clusters