16 micron Imaging in the GOODS fields with the Spitzer IRS Harry Teplitz (Spitzer Science Center)

The Usual Suspects North (IRS GTO + SV data) L. Armus, R. Chary, J. Colbert (SSC) V. Charmandaris (Crete) D. Weedman, J. Houck & IRS IT (Cornell) GOODS South R. Chary, J. Colbert D. Stern (SSC/JPL) M. Dickinson (NOAO) D. Elbaz D. Marcillac (CEA)

Why 16  m? PAH emission: 17.1 at z~ to z~ ,7.7,8.6 at z~1 Silicate absorption: 9.7  m detected at z~0.7 avoid siliacate at z~1.5 M51 (Smith et al.)

Why 16  m? Enhances Spitzer SED coverage factor of 3 -gap between IRAC & MIPS MIR slope, much fainter than spectroscopy

IRS “Peak-up” Imaging New Cycle 2 AOT provides science quality (RAW mode) imaging Blue and Red are observed in together Share common WCS SL spectra obtained in parallel 300+ hours requested in Cycle 2 75  Jy, 3 , in 120 s 54”x81” 1.8”/pixel < 2% distortion FWHM (16mm) = 2 pix

Depths achievable with PUI IRS lowres: mJy ULIRGs at z~1 PUI: mJy SB at z~1

“CHEAP” Imaging No PUI AOT in Cycle 1 Offset positioning of commanded spectra provides RAW-mode data Spectra AOT includes 18” nod, resulting in uneven coverage map

Pilot Study: GTO 16  m in GOODS-N Images centered on ISO or SCUBA sources (Charmandaris et al. 2004). 35 arcmin 2, 20 have 2 pt /pix 153 sources;  Jy. 24 sources in ISOCAM survey (Aussel et al. 1999) All sources detected in GOODS MIPS data

Comparison with ISO Possible confusion

HDF-North

GOODS South Data obtained in Feb ‘05 Some DCEs lost to latent imaging Nested Survey 150 sq. arcmin, 2 min per pix, 0.09 mJy 3  10 sq. arcmin, 8 min per pix, 0.04 mJy 3  515 sources detected, matched to IRAC Chan-1 No MIPS comparison until summer 2005

Number Counts Roughly in agreement with ISOCAM results Some confused ISOCAM sources are resolved by Spitzer The HDF-N pilot study is not an unbiased survey Marleau et al. (2004) find 24  m number counts peak at fainter flux than 15  m counts difference b/w 15 and 24  m counts is not the result of confusion of ISOCAM sources or systematic differences between the observatories

Redshifts Redshifts from e.g. TKRS, Hawaii, Cohen et al., in North, VIRMOS, etc. in the South Known redshift spikes in North are seen at z~0.45 and z~  m imaging may pick out members of the z~0.45 spike 16  m All (norm) NorthSouth

Chandra sources NORTH: 73 X-ray sources in the 2 Msec Chandra catalog within the pilot study area. 35 have 16  m counterparts ~30% of Spitzer 16  m sources have X-ray counterparts. SOUTH: 197 X-ray sources from the 1 Msec catalog 73 have 16  m counterparts ~15% of Spitzer 16  m sources have X-ray counterparts.

Chandra Sources Fadda et al. (2003) find 25% of ISO sources with have (1 Msec) Chandra counterparts. ~1/3 clearly “AGN dominated” Spitzer 16  m is lower at the 1 Msec level HB-detection 1/3 in N; 2/3 in S Indicative of more SF at fainter X-ray fluxes IR/X shows HB sources likely have significant AGN contrib. North

Extrapolating to LIR Spitzer template spectra ( Armus; Spoon; Brandl 2005 ) North: use slope of (H 0 =70,  -flat ) NorthSouth

LIRGs and ULIRGs We detect LIRGs and ULIRGs at z>1 More ULIRGs at higher z These objects dominate faint source counts ( Chary et al. 2004; Lagache et al ) At z~1.5, 16  m is preferable to 24

Flux Ratio Charmandaris et al. (2004) suggest that 16/24  m ratio separates AGN from starbursts

Evidence of PAH

Conclusions Spitzer 16  m imaging detects evidence for PAH emission at z~1 Depths achievable in short integrations can observe LIRGs at z>1 SEDs extend what is possible with spectroscopy easily detects AGN consistent with ISO