Spitzer Observations of Submm/Mm/Radio-Selected Galaxies Eiichi Egami (Univ. of Arizona) MIPS team: E. Le Floc'h, C. Papovich, P. Perez- Gonzalez, G. Rieke, M. Rieke, H. Dole, A. Alonso- Herrero, M. Blaylock, J. Cadien, J. Jones IRAC team: J.-S. Huang, P. Barmby, G. Fazio Lockman Hole SHADES team: J. Dunlop, R. Ivison, + others Bolocam team: J. Glenn + others (Lijiang)

Outline 1. Spitzer deep survey of the Lockman Hole East ● Submm/Mm/Radio selection: why should we care? ● 70/160 um observations 2. Spitzer observations of the brightest cluster galaxies (BCGs) in strongly cooling cluster cores ● IGM accretion onto a seed mass concentration -> another way to make galaxies IR-luminous (as opposed to galaxy-galaxy interaction). May play an important role at high-z (e.g., z > 3-4).

1. Deep Survey of the Lockman Hole (E) ● Lowest HI column density ● Abundance of ancillary data ● Especially deep X-ray/radio ● Wide submm coverage (SHADES) ● Deep optical (R,I,z) coverage We doubled the MIPS integrations during the spring of 2005.

850 um: 8 mJy 24 um: 80 uJy 20 cm: 20 uJy Radio (20cm) data must be very deep to be useful. Submm/Radio Selection vs. 24 um Selection

Why do we care about submm/mm/radio? ● Submm/Mm – Potential to detect extremely high-z galaxies (z>3). – Power to constrain IR SED together with Spitzer. ● Radio – Accuracy for estimating IR luminosity with the tight radio-IR luminosity correlation (e.g., 24um requires knowledge of PAH strength). – Combination of high spatial resolution (compact AGN vs. extended SB) and large field coverage. Answer: Provides effective selection for high-z infrared- luminous galaxies (e.g., LBG analogy). Also,

> 10^11 Lsun LIRGs ULIRGs Starbursts Le Floc'h et al. (2005)Perez-Gonzalez et al. (2005) LIRGs/ULIRGs become important at z > 1.

However, submm and radio have very different selection functions. provide complementary views of high-z IR-luminous galaxies MIPS 24um (80 uJy) VLA deep ( 50 uJy) VLA deepest (20 uJy)

Lockman Hole East 24um (14' x 14') red – 850um SCUBA, 16 src (Scott et al. 2002) blue – 1.2mm MAMBO, 23 src (Greve et al. 2004) green – 20cm VLA, 154 src (Ivison et al. in prep)

MIPS 24 um MIPS 70 um Radio selection efficiently picks up FIR luminous sources.

MIPS 70 um MIPS 160 um A submm/mm source strongly detected at 70 & 160 um

Far-IR SED of a mm-selected galaxy at z= um PAH Arp 220 still works.

SCUBA HAlf-Degree Extragalactic Survey (SHADES) ● PI: Jim Dunlop (Edinburgh) ● Lockman Hole (and Subaru-XMM Deep Field) ● 0.25 square degree x 2 fields (takes 3 years) ● 8 mJy (4 850um using SCUBA ● Deep VLA/MERLIN 20cm map (Ivison et al.) ● Wide-field near-IR images ● Deep optical images (IfA Deep ● 250, 350, and 500 um

SHADES - Lockman Hole ● 45% complete (402 square arcmin) ● 69 sources (> 3.5 sigma) 8 mJy sample (published) ● 16 sources (>3.5 sigma) ● ¼ of 69 SHADES sample ERO 8 mJy

Redshift distribution of 32 cold-type VLA sources (L IR > L ⊙ except for z<0.5) SCUBA sources Star Formation History – Updates available soon! Perez-Gonzalez et al. (2005) Need to go deeper and determine LF at high-z. (e.g., EVLA, stacking) 24um sample Radio/Submm

2. Spitzer Observations of BCGs in Strongly Cooling Cluster Cores ● Strongly cooling cores prevalent among X-ray- luminous clusters -> Cooling Flows – ROSAT/ASCA: as much as M ⊙ yr -1 – Chandra/XMM: cooling taking place but the cooling rates down by a factor of 10, possibly due to turn-on of radio AGNs. ● IGM (ICM) accretion to a seed galaxy – Another way to make galaxies infrared-luminous – May play a important role at high-z (z>3-4)

SEDs of 11 brightest cluster galaxies (BCGs) at z=

The IR sources are compact: D < 8 kpc

IR-luminous BCGs are located in clusters with the shortest cooling times Small scatter with the trend -> IGM (ICM) accretion (not galaxy-galaxy interaction) is likely responsible for the increased IR luminosities. Non-BCG range

Three-component SED model 1. Giant elliptical (gE) 2. ULIRG (Arp 220) 3. Radio AGN (power-law) A1835: L ⊙ Z3146: L ⊙ LIRGs ! A2390: L ⊙ Most BCGs harbor a radio AGN (70%)

IRS spectrum of Z3146: Strong PAH - IR luminosity of starburst origin Strong H 2 - a few times more luminous than N6240!

The two LIRG BCGs are overluminous in CO (1-0) for their IR luminosities. Similar to the radio galaxies presented by A. Evans. Result of IGM (ICM) accretion onto the BCGs?

Summary ● Submm/mm/radio-selected galaxies – Provide effective selection for high-z infrared-luminous galaxies – Allow accurate determination of SEDs & L IR together with Spitzer. ● Infrared-luminous brightest cluster galaxies (BCGs) – Increased L IR likely due to star formation triggered by IGM (ICM) accretion. – Similar process may play an important role at high-z (z>3-4).