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 integrationsduring the spring of 2005.

850 um: 8 mJy

24 um: 80 uJy20 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=1.4

3.3um 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 sigma) @ 850um using SCUBA

● Deep VLA/MERLIN 20cm map (Ivison et al.)

● Wide-field near-IR images (UKIDDS@UKIRT)

● Deep optical images (IfA Deep Survey@Subaru)

● BLAST @ 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(LIR > 1011 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 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)

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

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-galaxyinteraction) is likely responsible for the increased IR luminosities.

Non-BCGrange

Three-component SED model

1. Giant elliptical (gE)2. ULIRG (Arp 220)3. Radio AGN (power-law)

A1835: 8 • 1011 L⊙

Z3146: 4 • 1011 L⊙

LIRGs !

A2390: 3 • 1010 L⊙

Most BCGs harbor a radio AGN (70%)

IRS spectrum of Z3146: Strong PAH - IR luminosity of starburst originStrong 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 galaxiespresented 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 & LIR

together with

Spitzer.

● Infrared-luminous brightest cluster galaxies (BCGs)

– Increased LIR

likely due to star formation triggered by IGM

(ICM) accretion.

– Similar process may play an important role at high-z

(z>3-4).