1. 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)

2. 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).

3. 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.

4. 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

5. 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,

6. > 10^11 Lsun LIRGs ULIRGs Starbursts Le Floc'h et al. (2005)Perez-Gonzalez et al. (2005) LIRGs/ULIRGs become important at z > 1.

7. 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)

8. 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)

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

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

11. Far-IR SED of a mm-selected galaxy at z=1.4 3.3um PAH Arp 220 still works.

12. 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 sigma) @ 850um using SCUBA ● Deep VLA/MERLIN 20cm map (Ivison et al.) ● Wide-field near-IR images (UKIDDS@UKIRT)UKIDDS@UKIRT ● Deep optical images (IfA Deep Survey@Subaru) ● BLAST @ 250, 350, and 500 um

13. 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

14. Redshift distribution of 32 cold-type VLA sources (L IR > 10 11 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

15. 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 2000-3000 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)

16. SEDs of 11 brightest cluster galaxies (BCGs) at z=0.2-0.3

17. The IR sources are compact: D < 8 kpc

18. 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

19. Three-component SED model 1. Giant elliptical (gE) 2. ULIRG (Arp 220) 3. Radio AGN (power-law) A1835: 8 10 11 L ⊙ Z3146: 4 10 11 L ⊙ LIRGs ! A2390: 3 10 10 L ⊙ Most BCGs harbor a radio AGN (70%)

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

21. 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?

22. 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).