1. Star formation and submm/far- IR luminous galaxies Andrew Blain Caltech 26 th May 2005 Kyoto COSMOS meeting

2. Resolved `example’: the Antennae Excellent example of distinct opt/UV and IR luminosity –BUT modest luminosity Interaction long known, but great luminosity unexpected –~90% energy escapes at far-IR wavelengths Resolved images important –Relevant scales ~1” at high redshift HST WFPC2 ISOCAM CSO/SHARC-2 Dowell et al.

3. Current status and questions The most luminous high-z galaxies emit most radiation in far-IR Associated with forming ellipticals/bulges? Arguments: space density, dynamical CO mass, clustering –All will be better established by COSMOS –Need to find these things ‘ULIRGs’ - few 10 12 L o MAMBO (Eva Schinnerer & MPI/Bonn) and BOLOCAM (James Aguirre, U Colorado / CSO Caltech) –MAMBO 1.25mm, 1mJy RMS over 0.13 deg 2 –BOLOCAM 1.1mm, 2.5 mJy RMS over 0.28 deg 2 –I.e. BOLOCAM 3x coarser resolution, 3x higher noise, 2x wider area –BOLOCAM noise very uniform: can probe fluctuations from faint sources, at 1-  level Reasonable coverage over 15% of HST COSMOS –Future APEX/SCUBA-2 survey for whole region Knowledge of properties of far-IR/submm galaxies properties link to Spitzer strategies - in addition to BzK selection

4. Multiwavelength details Radio (RMS~10  Jy) is just adequate to reach the most luminous galaxies over z~1-2 Ground-based photometry will help with a real test of viability of photo-z’s for these objects - how red and recognizable? X-ray data over uniquely large field will identify the minority of powerful AGN in the sample –can use limits from Spitzer/submm to better assess opacity in AGN Can they be identified with red objects? –WFC3 –IF HST is serviced COSMOS may be key beneficiary

5. Spitzer colors/fluxes Spitzer rest near- IR and mid-IR red sources can be ID’ed as submm galaxies with reasonable efficiency 8/4.5 > 1, 24/8 >3 is reasonable cut –Met by COSMOS observations Should provide decent sample of high-z ULIRGS for LSS 8  m / 4.5  m 24  m / 8  m Big symbols are submm galaxies (SMGs): size scales with z Small symbols Lockman Hole & GOODS-N Spitzer galaxies

6. Appropriate Spitzer depths 24/8  m vs 24  m Large: SMGs Small: IRAC Lockman & GOODS-N Most existing examples found if sensitivity is to 100  Jy at 24  m Need to go ~30 times deeper at 8  m 24  m flux 24  m/8  m color

7. Summary COSMOS contains largest mm-wave images –Still at relatively early stage Much better multiwavelength coverage than other fields –AGN - starburst discrimination Spitzer data will assist dramatically –If deep enough to exploit to identify mid-IR bright galaxies in color-color space Limits on far-IR properties of the zoo of interesting lower-z objects are valuable Pathfinder for future instruments: APEX, SCUBA-2 & ultimately ALMA