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16 micron Imaging in the GOODS fields with the Spitzer IRS

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

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16 micron Imaging in the GOODS fields with the Spitzer IRS

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  1. 16 micron Imaging in the GOODS fields with the Spitzer IRS Harry Teplitz (Spitzer Science Center)

  2. 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) The Usual Suspects

  3. Why 16mm? • PAH emission: • 17.1 at z~0 • 11.3 to z~0.5 • 6.2,7.7,8.6 at z~1 • Silicate absorption: • 9.7 mm detected at z~0.7 • avoid siliacate at z~1.5 M51 (Smith et al.)

  4. Why 16mm? • Enhances Spitzer SED coverage • factor of 3 l-gap between IRAC & MIPS • MIR slope, much fainter than spectroscopy

  5. 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 mJy, 3s, in 120 s • 54”x81” • 1.8”/pixel • < 2% distortion • FWHM (16mm) = 2 pix

  6. Depths achievable with PUI • IRS lowres: 0.4-1 mJy ULIRGs at z~1 • PUI: 0.025-0.1 mJy SB at z~1

  7. “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

  8. Pilot Study: GTO 16 mm in GOODS-N • Images centered on ISO or SCUBA sources (Charmandaris et al. 2004). • 35 arcmin2, 20 have 2 pt /pix • 153 sources; 0.03 -- 0.8mJy. • 24 sources in ISOCAM survey (Aussel et al. 1999) • All sources detected in GOODS MIPS data

  9. Comparison with ISO Possible confusion

  10. HDF-North

  11. 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 3s • 10 sq. arcmin, 8 min per pix, 0.04 mJy 3s • 515 sources detected, matched to IRAC Chan-1 • No MIPS comparison until summer 2005

  12. 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 mm number counts peak at fainter flux than 15 mm counts • difference b/w 15 and 24 mm counts is not the result of confusion of ISOCAM sources or systematic differences between the observatories

  13. 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~0.9. • 16mm imaging may pick out members of the z~0.45 spike North South 16mm All (norm)

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

  15. Chandra Sources • Fadda et al. (2003) find 25% of ISO sources with have (1 Msec) Chandra counterparts. • ~1/3 clearly “AGN dominated” • Spitzer 16 mm 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

  16. Extrapolating to LIR • Spitzer template spectra (Armus; Spoon; Brandl 2005) • North: use slope of 16-24 • (H0=70, L-flat ) North South

  17. 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. 2004) • At z~1.5, 16 mm is preferable to 24

  18. Flux Ratio • Charmandaris et al. (2004) suggest that 16/24 mm ratio separates AGN from starbursts

  19. Evidence of PAH

  20. Conclusions • Spitzer 16 mm 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

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