Statistical Properties of Radio Galaxies in the local Universe

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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 Strauss, Ragnhild Lunnan
  (Princeton), Zheng Zheng (IAS)

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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

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motivation to make the bright end of the
luminosity function right
Croton et al (2006)
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motivation SZ surveys are happening!
Atacama Cosmology Telescope in construction
see Lin et al (0805.1750) for estimation of
effects of radio sources on SZ signal
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the sample

• using NYU-VAGC DR6 LSS galaxy sample as parent
  sample, containing 220,000 galaxies down to
  Mr?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

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bivariate luminosity function
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bivariate luminosity function
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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

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correlation function

• both galaxies and RGs are volume-limited and
  subject to same optical luminosity cut (Mr?21.5)
• RGs (red) more strongly clustered than galaxies
  (blue)
• clustering length comparable to groups of
  galaxies (10h-1Mpc)

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correlation function HOD modeling

• consider NRGNRG,cenNRG,sat
• NRG,cen1 if(M?Mmin)
• NRG,sat(M/M1)?
• HOD modeling suggests RGs are hosted by halos
  more massive than 1013 Msun (consistent with
  lensing results from Mandelbaum et al 2008)

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RGs in massive halos halo occupation number

• count galaxies and RGs at Mr?20.5 in 134 X-ray
  clusters from ROSAT all-sky survey
• number of galaxies goes as M0.8
• 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
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RGs in massive halos spatial distribution
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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?Mr?20.5
• within 0.5 Mpc, RL galaxies always have higher
  number of neighbors than RQ ones

Mpc
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RGs in dense regions
caution small number of SF galaxies in the
sample!
no RLAGNSF galaxy pairs at scaleslt1Mpc!
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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 whats 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