How to start an AGN: the role of host galaxy environment Rachel Gilmour (ESO Chile & IfA, Edinburgh) Philip Best (Edinburgh), Omar Almaini & Meghan Gray (Nottingham) or stop

Why do some galaxies have AGN? Gas -> black hole = AGN Internal: size, morphology, star-formation Historical: previous activity -- depletion, feedback External: mergers, close encounters, tidal field, strangulation, ram-pressure stripping No AGN 0.01% 30%

External effects on galaxies Morphology: spirals -> S0s Star-formation rate: high -> low Q1 – Do the frequency and properties of AGN depend on the external environment? Q2 – Can this be explained by the changes in the type of host galaxies?

Where are AGN found? Miller '03, Wake '05 Kauffmann '04, Coldwell '02 Dressler '99 Eckart '05 Ruderman '05 Johnson '03 Porciani '04 Ledlow & Owen '96 Reddy '04 Best '04 Best '02 Galaxy density / AGN clustering Redshift ~0.8 ~0.1 Optical Radio X-ray

My projects 1. AGN in the A901/2 supercluster Detailed study X-ray detected AGN Includes groups, clusters, filaments, field etc. 2. Statistical survey of AGN in > 100 galaxy clusters X-ray detected AGN Find statistical excess of sources compared to “blank” field Split sample by cluster properties and redshift

A901  A901a A901b A902 Filament SW group The A901/2 supercluster (z=0.17) Optical data (from COMBO-17 team) Deep R-band imaging 17-band photometric redshifts for ~18000 objects (m R <24) 1240 supercluster galaxies found 282 supercluster spectra from 2dF Weak lensing map Spitzer data MIPS 24-micron sources X-ray data 12 ksec ROSAT images (HRI) 90 ksec XMM-Newton image People: Meghan Gray, Chris Wolf + COMBO-17 team, Bell and Papovich, Andy Taylor.

A901  A901a A902 A901b SW group z=0.5 cluster Emission A901/2: Finding the supercluster AGN Identify point sources Sources - wavelet detection on images from 3 cameras150 - remove uncertain and extended sources139

A901/2: Finding the supercluster AGN Identify point sources Sources - wavelet detection on images from 3 cameras150 - remove uncertain and extended sources139 Match with optical sources - R-band, using likelihood ratios from random sources - also Spitzer 24-micron data to resolve uncertainties 88

A901/2: Finding the supercluster AGN Identify point sources Sources - wavelet detection on images from 3 cameras150 - remove uncertain and extended sources139 Match with optical sources - R-band, using likelihood ratios from random sources - also Spitzer 24-micron data to resolve uncertainties 88 Determine supercluster membership - COMBO-17 photometric redshifts and 2dF spectra11 - Manual check for AGN contaminated sources 12

Identify point sources Sources - wavelet detection on images from 3 cameras150 - remove uncertain and extended sources139 Match with optical sources - R-band, using likelihood ratios from random sources - also Spitzer 24-micron data to resolve uncertainties 88 Determine supercluster membership - COMBO-17 photometric redshifts and 2dF spectra11 - Manual check for AGN contaminated sources 12 Find out which are AGN - check for low-mass X-ray binaries using fx/fB 12 - check for star-forming galaxies using Lx, hardness ratios, fx/fR, star-formation rates from OII lines and OIII/Hβ line ratios 11 A901/2: Finding the supercluster AGN

A901/2: Finding the non-AGN Aim: Compare the AGN environments with control samples of galaxies which have: no AGN similar magnitudes similar colours where AGN could be detected Method: 100 samples of 66 galaxies equal number of galaxies in each 0.5 magnitude bin exclude cluster centres use K-S and Kuipers tests

A901/2: AGN host galaxies RESULT 1 : All of the AGN lie in galaxies with m R < 20 RESULT 2 : ~5% of bright supercluster galaxies contain X-ray detected AGN (~1% optically detected) RESULT 3 : Brighter galaxies have equal luminosity or fainter AGN (92%)

A901/2: Separating the Environments Define by hand: Clusters (A901a, A901a, A901b, A902) Groups Outskirts of large clusters and groups Filaments

Two parameter separation for environments: (1.5' = 250 kpc) Local density: clusters & field Local colour: groups & edges filaments & clusters 1.5' A901/2: Separating the Environments - 2

A901/2: Separating the environments: Does it work for all galaxies? Cluster Red group / Edge Blue group Filament Field

cluster filament field group edge A901/2: Environments of AGN 3.3% - AGN match control in 2D space 18% -AGN match control in edge and group 4% - AGN match control in 1D space along cluster line (30% in density only) >98%-Lx decreases along the cluster line direction Cluster line

A901/2: Conclusions 1. ~5% of bright supercluster galaxies contain X-ray detected AGN. 2. All of the AGN lie in galaxies with m R < 20. more gas, larger black hole 3. The lack of AGN in fainter galaxies is not due to a L X – m R correlation. no correlation or large galaxies are more stable 4. Compared to other similar galaxies, those with AGN lie in group or edge like environments – moderate density and bluer than average. suppression in centre, triggering on outskirts, tracing star-formation, more smaller galaxies 5. AGN in more cluster like environments are fainter. galaxies with more gas need less disturbance, strangulation reduces available gas

Where are AGN found? Miller '03, Wake '05 Kauffmann '04, Coldwell '02 Dressler '99 Eckart '05 Ruderman '05 Johnson '03 Porciani '04 Ledlow & Owen '96 Reddy '04 Best '04 Best '02 Galaxy density / AGN clustering Redshift A901/2 ~0.8 ~0.1 Optical Radio X-ray

Chandra Clusters: Method Find sources in fields of galaxy clusters Predict source distribution assuming no cluster AGN Compare flux and radial distributions of excess sources AGN Abell 1689 HST Credit: NASA / N. Benitez

Chandra Clusters: The sample Secure redshift and z > 0.1 Exposure > 10 ksec X-ray detected cluster (after data reduction) === 139 good cluster fields === + 8 with z > 1 Redshift distribution Morphology 89 'relaxed' 23 'disturbed' 19 'contaminated' 8 high redshift (z > 1) Luminosity z 0.1 – 70 x erg/sec

Chandra Clusters: Prediction Blank fields – deep surveys (22) and high redshift QSOs (22) Sensitivity map – background, size, exposure, accuracy + errors Background Source sizeGood region Exposure time Sensitivity map

Chandra Clusters: Lensing Lensing changes background sources : flux increases number density decreases Net result: lensing causes ~ 10% reduction in the central 0.5 Mpc INPUTS: Background AGN redshift distribution (3 used) Cluster model (SIS now, NFW in future) Cluster luminosity => mass N Lx Model = Blank fields + Sensitivity map + Lensing

Chandra Clusters: Radial position AGN lie between 0.5 and 1 Mpc from the cluster centre. Excess of 1 or 2 sources per cluster Radial trend seen in physical distance (Mpc) Lack of AGN in central regions is not due to the intra-cluster emission

Chandra Clusters: Suppression? AGN appear to be suppressed in moderate redshift clusters N X (flux) N X (Cl,flux) N Opt (>L*) N Opt (Cl,>L*) = 25 galaxies > L* 5 galaxies > L* 1 galaxy > L* Clusters with low L X (~1x10 44 ) have ~6 galaxies > L* (De Propris 2004) (Excess per average field = excess per square degree x average field size)

Chandra Clusters: Evolution The evolution of AGN in clusters is faster than in the field 25 gal. 25 galaxies 5 galaxies Redshift samples < 1 have similar luminosity & morphology distributions

Chandra Clusters: Radial Evolution High redshift clusters have more AGN at larger radii

Chandra Clusters: Morphology Disturbed clusters have more low luminosity sources Disturbed clusters also have excess at higher radius

Chandra Clusters: Results AGN lie between 0.5 and 1 Mpc from the cluster centre. AGN appear to be suppressed in moderate redshift clusters. The evolution of AGN in clusters is faster than in the field. High redshift clusters have more AGN at larger radii. Disturbed clusters have more low luminosity sources.

Where are AGN found? Miller '03, Wake '05 Kauffmann '04, Coldwell '02 Dressler '99 Eckart '05 Ruderman '05 Johnson '03 Porciani '04 Ledlow & Owen '96 Reddy '04 Best '04 Best '02 Galaxy density / AGN clustering Redshift ~0.8 ~0.1 Optical Radio X-ray A901/2

AGN lie between 0.5 and 1 Mpc from the cluster centre. AGN appear to be suppressed in moderate redshift clusters. The evolution of AGN in clusters is faster than in the field. High redshift clusters have more AGN at larger radii. Disturbed clusters have more low luminosity sources. Results ~5% of bright supercluster galaxies contain X-ray detected AGN. All are in galaxies with m R < 20. The lack of AGN in fainter galaxies is not due to a L X – m R correlation. Compared to similar galaxies, those with AGN lie in group or edge like environments – moderate density and bluer. AGN in more cluster like environments are fainter.

AGN lie between 0.5 and 1 Mpc from the cluster centre. AGN appear to be suppressed in moderate redshift clusters. The evolution of AGN in clusters is faster than in the field. High redshift clusters have more AGN at larger radii. Disturbed clusters have more low luminosity sources. AGN in more massive clusters have a larger radial spread. Results ~5% of bright supercluster galaxies contain X-ray detected AGN. All are in galaxies with m R < 20. The lack of AGN in fainter galaxies is not due to a L X – m R correlation. Compared to similar galaxies, those with AGN lie in group or edge like environments – moderate density and bluer. AGN in more cluster like environments are fainter.

Chandra Clusters: Cluster size AGN in more massive clusters have a larger radial spread Expect mass to go as L x  M 4/3 Expect radius to go as R  ~L x 0.3