The interplay between the brightest cluster galaxy and the intra-cluster medium via AGN feedback.

Transcription

1 The interplay between the brightest cluster galaxy and the intra-cluster medium via AGN feedback. John Stott Durham University Stott et al. 2012, MNRAS 2012, 422, 2213, arxiv: The XCS Collaboration (PI: K Romer) +Ryan Hickox, Alastair Edge, Ian McCarthy Joop Schaye

2 Outline The XMM Cluster Survey (XCS) BCG-cluster scaling relations BCG AGN interplay with the ICM BCG influence on cluster Lx-Tx relation BCG radio properties in relation to ICM

3 Outline The XMM Cluster Survey (XCS) BCG-cluster scaling relations BCG AGN interplay with the ICM BCG influence on cluster Lx-Tx relation BCG radio properties in relation to ICM

4 XMM Cluster Survey The XMM Cluster Survey aims to mine the XMM science archive for galaxy clusters The science goals of the XCS are: To measure cosmological parameters σ8, ΩM, ΩΛ to 5, 10 and 15 per cent accuracy respectively To study the evolution of the cluster gas (i.e., the luminosity temperature relation) to high redshift To provide a sample of high redshift clusters that can be used to test theories of cluster galaxy formation and evolution

5 DR1 sample details Blue are new to literature, Green is the full sample Mehrtens et al clusters with Tx Lloyd-Davies et al. 2011

6 Properties of the DR1 sample Comparison with some other Tx data releases Clusters (> z) Maughan 07 Vikhlinin 09 XMM-LSS Mantz z More low redshift systems

7 Properties of the DR1 sample Comparison with some other Tx data releases Clusters (> z) XCS Maughan 07 Vikhlinin 09 XMM-LSS Mantz z More low redshift systems

8 Properties of the DR1 sample Comparison with some other Tx data releases Clusters (> Tx) Maughan 07 Vikhlinin 09 XMM-LSS Mantz T x (kev) Excellent resource of group mass systems

9 Properties of the DR1 sample Comparison with some other Tx data releases Clusters (> Tx) XCS Maughan 07 Vikhlinin 09 XMM-LSS Mantz T x (kev) Excellent resource of group mass systems

10 DR1 L-T relation (no selection function) 10 2 Bolometric Luminosity (10 44 erg s 1 ) Temperature (kev) Algorithms paper Lloyd-Davies et al Lx-Tx and its evolution appears in Hilton et al arxiv:

11 XCS Cosmology predictions XCS predictions based on LCDM mock catalogue, XCS selection function (need to know LT relation), and MT relation Parameters derived from n(m,z) (Sahlen et al. 2009)

12 Outline The XMM Cluster Survey (XCS) BCG-cluster scaling relations BCG AGN interplay with the ICM BCG influence on cluster Lx-Tx relation BCG radio properties in relation to ICM

13 BCG AGN feedback in Clusters Powerful radio emitting jets from the vicinity of the black hole can blow out cavities in the ICM

14 The sample 123 XCS galaxy clusters with z<0.3 that overlap with SDSS and FIRST for optical and radio coverage. Tx= kev Lx= x1044 erg s -1 No evidence for strong Lx dependence on z.

15 The sample BCG photometry I-band model magnitudes (de Vauc. n=4 Sersic) Stellar masses derived from photometry BCG radio data from FIRST All extended radio sources with multiple components

16 Key BCG assumptions To study BCG affect in time averaged sense, ignoring radio: BCG black hole mass is proportional to stellar mass (MBH-bulge/MBH-sigma relation) ALL BCGs are AGN but because of duty-cycle only a fraction are on at any given time The most massive BCGs will therefore have had more influence on their clusters ICM in a timeaveraged sense over the lifetime of the system. (Lin & Mohr 2007, upper Lrad envelope correlates with stellar mass)

17 Key ICM assumptions Both Lx and Tx are proportional to cluster mass Tx is a measure of the virial temperature Lx is proportional to the integral of the square of the gas density For a self similar cluster (ICM properties governed solely by gravitational heating): A departure from this is caused by nongravitational processes

18 Theoretical motivation Lx-Tx relation from OWLS simulations (McCarthy et al. 2010) Demonstrates effect of AGN feedback on ICM First order: AGN feedback lowers Lx for a given Tx NB: this is a consequence of both energy injection at z>1 from L* galaxies and a maintenance mode for the BCG

19 Scaling relations b Points: XCS sample, Crosses: OWLS simulations (which provide ICM and BCG stellar mass information) BCG mass correlates with ICM properties OWLS in the right ball park with a=0.78, is steep compared to some studies (e.g. a=0.12 Whiley 2008) but comparable to the most similar (Mittal 2009) with a= also using BCES fitting and Sersic-style total magnitudes

20 Scaling relations b Points: XCS sample, Crosses: OWLS simulations (which provide ICM and BCG stellar mass information) BCG mass correlates with ICM properties OWLS in the right ball park with a=0.78, is steep compared to some studies (e.g. a=0.12 Whiley 2008) but comparable to the most similar (Mittal 2009) with a= also using BCES fitting and Sersic-style total magnitudes

21 Lx-Tx relation for this sample

22 Observed Lx-Tx relation influence of BCG mass Clusters with most massive BCGs have steeper Lx-Tx relation (exponent~3) Clusters with least massive BCGs follow self-similarity (exponent~2) 3 sigma significance - with cross-over occurring around 2keV (1x10 43 erg s -1, MSol)

23 Lx-Tx relation influence of BCG mass in OWLS simulations The OWLS simulation also shows dependence on BCG mass

24 Lx-Tx relation influence of BCG distance from X-ray centroid of cluster similar story with distance of BCG to X-ray centroid: co-located BCGs = steeper relation.

25 BCG influence on Lx-Tx relation It seems that the Lx-Tx relation is interrelated with the mass of the BCG - which correlates with mass of black hole. Also influenced by distance from BCG to X-ray centroid (peak in ICM density). Therefore the BCGs with the largest black holes and most effective supply of gas cause departure of Lx-Tx relation from pure gravitational heating. Similarly steep relations seen for cool-core clusters and those with extended radio sources (e.g. Mittal 2009, Magliocchetti 2007)

26 Radio properties of BCGs Radio loud definition (LR>2x10 23 WHz -1 ) Radio luminosity distribution of BCGs in our sample ~25% BCGs radio loud - similar to other X-ray and optical cluster surveys (eg Best 2007, Lin&Mohr 2007)

27 Radio-loud scaling relations No correlations between Cluster mass or BCG mass and radio luminosity - probably washed out by duty-cycle. Instead look at radio loud fraction correlations

28 Radio-loud Fraction relations No evidence of correlation between RLF and BCG mass although in agreement with Best 2007 correlation Some evidence that RLF increases with proximity to ICM peak (greater fuel supply?)

29 Radio loud Fraction relations RLF correlates most strongly with cluster mass with the data showing a jump at MSol (2keV, 1x10 43 erg s -1 ) - same as crossover mass between the steepened Lx-Tx and self-similarity

30 Toy model of energetics From Birzan 2004 EAGN= Ratio of these energies depends on cluster mass Assume constant Lrad and account for duty-cycle If crossover mass/radio-loud jump mass (at Tx=2keV) corresponds to where AGN FB starts to be significant (~10%) then eta~5.5 Diagram shows where AGN feedback dominates and where ICM cooling dominates Horizontal lines show where AGN feedback injected energy is10% and 100% of the ICM thermal energy in cluster core (*factor of 2 higher in vicinity of AGN - Lin & Mohr 2007)

31 Implications The key parameters that govern the duty-cycle of AGN in BCGs are primarily the cluster mass and to a lesser extent the BCG offset from the cluster X-ray centroid, but not BCG mass. Supermassive black holes at the centres of BCGs in cluster cores know more about their host cluster than they do about their host galaxy, consistent with the OWLS simulations (Booth & Schaye 2010). The sub pc scale is governed by the 100s kpc scale and not the kpcscale. We conclude that the connection must be due to the amount of fuel available and thus what drives AGN activity in the central galaxies of clusters is the availability of a large, cooling gas supply that can be effectively fed to the central black hole (cool-core AGN connection). Relates to Lx-Tx departure for massive BCGs most likely in cool-cores. The results lead us to conclude that 2 kev (10 14 MSol, erg s 1 ) is an important mass scale which delineates the boundary between cooling dominated systems above this mass and the AGN feedback dominated systems below. We propose that this is an excellent empirical demarcation between what is referred to as a group and what is a cluster

32 Implications The key parameters that govern the duty-cycle of AGN in BCGs are primarily the cluster mass and to a lesser extent the BCG offset from the cluster X-ray centroid, but not BCG mass. Supermassive black holes How at the this centres cooling of BCGs in gas cluster cores know more about their host cluster than they do about their host galaxy, consistent with the OWLS simulations (Booth & on Schaye kpc 2010). scales The sub pc is scale is governed by the 100s kpc scale and not the kpcscale. funnelled down into the We conclude that the connection must be due to the amount of fuel available and thus accretion disk of the what drives AGN activity in the central galaxies clusters is the availability of a large, cooling gas supply that black can be effectively hole remains fed to the central an black hole (cool-core AGN connection). Relates to Lx-Tx departure for massive BCGs most likely in cool-cores. open question. The results lead us to conclude that 2 kev (10 14 MSol, erg s 1 ) is an important mass scale which delineates the boundary between cooling dominated systems above this mass and the AGN feedback dominated systems below. We propose that this is an excellent empirical demarcation between what is referred to as a group and what is a cluster

33 Cartoon Lower RLF: less massive halo, noncentral position High RLF: massive halo, central position

34 Paper and Further work Stott et al. 2012, MNRAS, 422, 2213, arxiv: Data available here: ~jps/stott2012/stott2012.cat Now going to compare to the results of the Millennium Gas simulation, GALFORM Extension to higher redshift XCS data here:

35 Lx Tx normalisation evo. Text