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How to start an AGN: the role of host galaxy environment

or stop. 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). Why do some galaxies have AGN?. Gas -> black hole = AGN Internal : size, morphology, star-formation

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How to start an AGN: the role of host galaxy environment

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  1. or stop 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)

  2. 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%

  3. 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?

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

  5. 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

  6. The A901/2 supercluster (z=0.17) People: Meghan Gray, Chris Wolf + COMBO-17 team, Bell and Papovich, Andy Taylor. Optical data (from COMBO-17 team) • Deep R-band imaging • 17-band photometric redshifts for ~18000 objects (mR<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 A901a A901a A901b Filament A902 SW group

  7. A901/2: Finding the supercluster AGN • Identify point sources Sources - wavelet detection on images from 3 cameras 150 - remove uncertain and extended sources 139 A901a A901b A901a Emission z=0.5 cluster SW group A902

  8. A901/2: Finding the supercluster AGN • Identify point sources Sources - wavelet detection on images from 3 cameras 150 - remove uncertain and extended sources 139 • Match with optical sources - R-band, using likelihood ratios from 14000 random sources - also Spitzer 24-micron data to resolve uncertainties 88

  9. A901/2: Finding the supercluster AGN • Identify point sources Sources - wavelet detection on images from 3 cameras 150 - remove uncertain and extended sources 139 • Match with optical sources - R-band, using likelihood ratios from 14000 random sources - also Spitzer 24-micron data to resolve uncertainties 88 • Determine supercluster membership - COMBO-17 photometric redshifts and 2dF spectra 11 - Manual check for AGN contaminated sources 12

  10. A901/2: Finding the supercluster AGN • Identify point sources Sources - wavelet detection on images from 3 cameras 150 - remove uncertain and extended sources 139 • Match with optical sources - R-band, using likelihood ratios from 14000 random sources - also Spitzer 24-micron data to resolve uncertainties 88 • Determine supercluster membership - COMBO-17 photometric redshifts and 2dF spectra 11 - 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

  11. 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

  12. A901/2: AGN host galaxies RESULT 1 : All of the AGN lie in galaxies with mR < 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%)

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

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

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

  16. 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 field Cluster line edge filament group

  17. A901/2: Conclusions 1. ~5% of bright supercluster galaxies contain X-ray detected AGN. 2. All of the AGN lie in galaxies with mR < 20. more gas, larger black hole 3. The lack of AGN in fainter galaxies is not due to a LX – mR 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

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

  19. Abell 1689 AGN 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 HST Credit: NASA / N. Benitez

  20. Morphology 89 'relaxed' 23 'disturbed' 19 'contaminated' 8 high redshift (z > 1) Redshift distribution Luminosity 0.1 – 70 x 1044 erg/sec z 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

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

  22. 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

  23. Chandra Clusters: Radial position 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 AGN lie between 0.5 and 1 Mpc from the cluster centre.

  24. 25 galaxies > L* 5 galaxies > L* 1 galaxy > L* NX(flux) NX(Cl,flux) NOpt(>L*) NOpt(Cl,>L*) = Chandra Clusters: Suppression? Clusters with low LX (~1x1044) have ~6 galaxies > L*(De Propris 2004) (Excess per average field = excess per square degree x average field size) AGN appear to be suppressed in moderate redshift clusters

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

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

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

  28. 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.

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

  30. Results ~5% of bright supercluster galaxies contain X-ray detected AGN. All are in galaxies with mR < 20. The lack of AGN in fainter galaxies is not due to a LX – mR 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.

  31. Results ~5% of bright supercluster galaxies contain X-ray detected AGN. All are in galaxies with mR < 20. The lack of AGN in fainter galaxies is not due to a LX – mR 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.

  32. Chandra Clusters: Cluster size Expect mass to go as Lx M4/3 Expect radius to go as R  ~Lx 0.3 AGN in more massive clusters have a larger radial spread

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