16 micron imaging in the goods fields with the spitzer irs
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
16 micron Imaging in the GOODS fields with the Spitzer IRS
Harry Teplitz(Spitzer Science Center)
The Usual SuspectsNorth (IRS GTO + SV data)L. Armus, R. Chary, J. Colbert (SSC)V. Charmandaris(Crete)D. Weedman,J. Houck & IRS IT (Cornell)
GOODS SouthR. Chary,J. ColbertD. Stern(SSC/JPL)M. Dickinson (NOAO)D. ElbazD. Marcillac(CEA)
Why 16m?
• 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 m detected
at z~0.7• avoid siliacate
at z~1.5M51 (Smith et al.)
Why 16m?
• 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: 0.4-1 mJy ULIRGs at z~1
• PUI: 0.025-0.1 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 arcmin2, 20 have 2 pt /pix
• 153 sources; 0.03 -- 0.8Jy.• 24 sources in ISOCAM
survey (Aussel et al. 1999) • All sources detected in
GOODS MIPS data
Comparison with ISO
Possibleconfusion
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~0.9. • 16m imaging may pick out members of the z~0.45 spike
16mAll (norm)
North South
Chandra sources• NORTH: 73 X-ray sources in
the 2 Msec Chandra catalog within the pilot study area.• 35 have 16m counterparts • ~30% of Spitzer 16m
sources have X-ray counterparts.
• SOUTH: 197 X-ray sources from the 1 Msec catalog• 73 have 16m counterparts • ~15% of Spitzer 16m
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 16-24• (H0=70, -flat )
North South
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 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