FRI RADIO GALAXIES AT z > 1 STUDYING THE BUILDING BLOCKS OF TODAY'S MOST MASSIVE GALAXIES AND CLUSTERS Marco Chiaberge Space Telescope Science Institute and INAF-IRA Bologna G. Tremblay (STScI) A. Capetti (INAF-OATO) D. Macchetto (STScI) W.B. Sparks (STScI) P. Tozzi (INAF-OATS)

MORPHOLOGICAL CLASSIFICATION OF RADIO GALAXIES FR IFR II LOW POWERHIGH POWER Fanaroff & Riley 1974 L 178 ~< 2 x W Hz -1 L 178 >~ 2 x W Hz -1

The radio-loud AGN unification model FR I BL Lac Urry & Padovani 1995

THE HST VIEW of FR I radiogalaxies Complete sample: 33 objects, 32 with HST R-band observations The HST/WFPC2 snapshot survey of 3CR radio sources (P.I. Sparks) Chiab, Capetti & Celotti 1999

FRI RADIO GALAXIES AT LOW Z ● ASSOCIATED TO GIANT ELLIPTICAL GALAXIES HOSTING THE MOST MASSIVE BLACK HOLES (e.g. Donzelli et al. 2007, Zirbel & Baum 1997) ENVIRONMENT: CLUSTERS (e.g Zirbel 1997) MOST FRI ARE HOSTED BY cD GALAXIES PROPERTIES OF THE AGN: PROBABLY “RIAF” ACCRETION, RELATIVISTIC JET NO THICK TORI, NO BLR, NO FRI-QSO, NO IR EXCESS ( Chiaberge et al 1999) DIFFERENT FROM ALL OTHER AGN MORE SIMILAR TO “INACTIVE” GALAXIES

FR I radio galaxies are known in the nearby universe only A few FR Is (~10) are present in the 6C and 7C samples up to z~0.8 A few low-power radio galaxies are found in the 2SLAQ survey (z < 0.7) (Sadler et al. 2007) The most distant FR I known is at z ~1 (Snellen & Best 2001) In the 3CR catalog FRIs are present only for z < 0.2

WHY ARE WE LOOKING FOR FRIs AT 1 < z <2 Cosmological Evolution of FRIs is basically unknown Hints for strong evolution up to z~0.7 ( Sadler et al. 2007) FRI-QSO are absent in the low-z universe: what is the fraction of FRI-QSO at high z? (e.g Blundell et al. 2002, Heywood et al. 2007) The role of FRI in the framework of the AGN unification scheme FRIs as probes for studying the formation and co-evolution of the most massive galaxies and most massive BH FRI as tracers of high-z clusters Differently from FRIIs, the AGN does not dominate the emission in crucial bands (IR, X-rays)

FLUX LIMITED SAMPLES CANNOT BE USED The search method must make use of multiwavelength information COSMOS (Scoville et al 2007) is perfectly suitable for this. Radio selection (from FIRST): what is the flux of an FR I radio galaxy of a certain radio power in the redshift bin 1 < z < 2? (1mJy < F < 13mJy) Morphology: FRIIs are excluded Optical selection: optical counterparts are found using the COSMOS catalog (Mobasher et al 2007). Bright sources (detected in SDSS) are excluded (probably nearby starburst galaxies) U-band dropouts are excluded (z > ~ 2.5) Basic assumptions: the radio properties of high-z FRIs are similar to those of low z FRIs the optical properties of high-z FRIs are similar to those of high-z FRIIs

182 radio sources in FIRST 133 match the flux requirements 28 FRI candidates 7 FRI-QSO candidates > 4 cluster candidates RESULTS COSMOS optical data are NOT deep enough to detect a large fraction of cluster galaxies at z > 1

(Chiaberge et al. in prep) Using photometric redshifts (Mobasher et al 2007) and the K-z relation for radio galaxies we can check that our selection criteria work K-z relation for radio galaxies hosts

Projected linear size ~100kpc z phot = 1.85 COSMOS-VLA COSMOS HST/ACS F814W 1 orbit 1”

Elliptical hosts (z phot = 1.31)

z phot = 2.09 z phot = 2.04 z phot = 0.72 z phot = ” VLA ACS WFC F814W

Using FRIs to find high-z clusters z phot = 1.3

z phot = 2.09 R = 3.  m G = V B = B 2'

SUMMARY Future work: Spectroscopic redshifts (this week at Galileo, GEMINI?) Stacking Xray data to search for cluster/ICM emission Radio (low and high frequency, higher resolution data) HST DEEP IMAGING TO STUDY HOST GALAXIES AND CLUSTERS – ACS (OPTICAL) – WFC3 (IR) We discovered FRI radio galaxies at z >1 FRIs can be used to study the formation and evolution of the most massive galaxies and their relationship with supermassive black holes FRIs can be used to find high z clusters