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Statistical Properties of Radio Galaxies in the local Universe Yen-Ting Lin Princeton University Pontificia Universidad Católica de Chile Yue Shen, Michael.

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Presentation on theme: "Statistical Properties of Radio Galaxies in the local Universe Yen-Ting Lin Princeton University Pontificia Universidad Católica de Chile Yue Shen, Michael."— Presentation transcript:

1 Statistical Properties of Radio Galaxies in the local Universe Yen-Ting Lin Princeton University Pontificia Universidad Católica de Chile Yue Shen, Michael Strauss, Ragnhild Lunnan (Princeton), Zheng Zheng (IAS)

2 outline motivations science goals –consensus of radio galaxies (RGs) hosted by massive galaxies in the local universe (z  0.3) –formation mechanism of RGs –identification of interesting objects for detailed study the sample several statistics to look at –relationship with radio-quiet (RQ) population –dependence on the environment

3 motivation: to make the bright end of the luminosity function right Croton et al (2006)

4 motivation: SZ surveys are happening! credit: CXO Carlstrom et al (2002) Atacama Cosmology Telescope in construction see Lin et al (0805.1750) for estimation of effects of radio sources on SZ signal

5 using NYU-VAGC DR6 LSS galaxy sample as parent sample, containing ~220,000 galaxies down to M r  –20.5 (about M * ) cross-matched with NVSS and FIRST surveys at 1.4 GHz to generate the largest radio galaxy catalog to date: 10,500 RGs stronger than 3mJy improvements over previous studies –construction of several volume-limited subsamples –90% of RGs have measured redshift –all RGs visually inspected to secure matches and measurement of fluxes –morphology information of radio sources –high S/N measurement of correlation functions –halo occupation distribution (HOD) modeling the sample

6 bivariate luminosity function whole sample M  -20.5 volume-limited M  -21.5 volume-limited

7 bivariate luminosity function

8 optical luminosity function 0.02  z  0.132 108,873 galaxies 2,253 RGs 2.1% of galaxies more luminous than M * have radio power logP  23.12 fiber collision correction applied

9 correlation function both galaxies and RGs are volume-limited and subject to same optical luminosity cut (M r  –21.5) RGs (red) more strongly clustered than galaxies (blue) clustering length comparable to groups of galaxies (~10h -1 Mpc)

10 correlation function: HOD modeling consider N RG =N RG,cen +N RG,sat N RG,cen =1 if(M  M min ) N RG,sat =(M/M 1 )  HOD modeling suggests RGs are hosted by halos more massive than 10 13 M sun (consistent with lensing results from Mandelbaum et al 2008)

11 RGs in massive halos: halo occupation number count galaxies and RGs at M r  – 20.5 in 134 X-ray clusters from ROSAT all-sky survey number of galaxies goes as M 0.8 occupation number of RGs not a strong function of cluster mass 1435 galaxies, 85 RGs (~6%) 62/134 (=46%) clusters host RGs among these, 34 have RL BCGs 44 clusters host only 1 RG, 20 of these are BCG 25% of BCGs are RL 3.9% of non-BCG galaxies are RL NOTE: 2.1% of galaxies are RL globally BCGs clusters w/o RGs

12 RGs in massive halos: spatial distribution

13 RGs in dense regions excess number of neighbors –1000 RGs, 1000 RQ galaxies matched to optical luminosity, apparent magnitude, and redshift –count nearby objects out to 2 Mpc from SDSS photometric catalog, within –23.5  M r  –20.5 –within ~0.5 Mpc, RL galaxies always have higher number of neighbors than RQ ones Mpc

14 RGs in dense regions no RLAGN–SF galaxy pairs at scales<1Mpc! caution: small number of SF galaxies in the sample!

15 summary observations: –given optical luminosity and color, RGs are more strongly clustered than the corresponding RQ galaxy sample –large scale clustering implies hosts are group or cluster-sized halos –RGs very centrally concentrated towards halo center ingredients for RL AGN phenomenon –dense environment –presence of intracluster/intragroup gas: confining pressure –low level supply of gas: what’s the source? work in progress –dissection of the bivariate LF –environment of high and low-excitation RL AGNs (e.g., FRI vs FRII) –relationship with X-ray and optical AGNs


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