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Status of the Spitzer Warm MissionSpitzer Extended Deep Survey (SEDS)
Giovanni G. Fazio
Harvard Smithsonian Center for Astrophysics
and the SEDS Team
AEGIS Meeting, Toledo Spain
SEDS: Spitzer Extended Deep Survey
• PI: Giovanni Fazio– 47 Co-I’s from 23 institutions
• Primary Scientific Objective– Galaxy formation in the early Universe– Obtain first complete census of the assembly of stellar mass and
black holes as a function of cosmic time back to the era of reionization
– Series of secondary objectives
• Unbiased survey 12 hrs/pointing at 3.6 and 4.5 microns ([3.6] = 26 AB, 5 ) in five well-studied fields (0.9 sq deg)– 10 times area of deep GOODS survey
• Total Time: 2108 hrs over 1.5 years• No proprietary time on data
SEDS Co-Investigators
Harvard Smithsonian Center for Astrophysics: Lars Hernquist, Matt Ashby, Jiasheng Huang, Kai Noeske, Steve Willner, Stijn Wuyts, T.J. Cox, Yuexing Li, Kamson Lai
Max-Planck-Institut für Astronomie: Hans-Walter Rix, Eric Bell, Arjen van der Wel
University of Califronia, Santa Cruz: Sandy Faber, David Koo, Raja Guhathakurta, Garth Illingworth, Rychard Bouwens
NASA/GSFC: Sasha Kashlinsky, Rick Arendt, John Mather, Harvey Moseley
Carnegie Observatories: Haojin Yan, Ivo Labbe, Masami Ouchi
University of Pittsburgh: Jeff Newman
Space Telescope Science Institute: Anton Koekemoer
University of Arizona: Ben Weiner, Romeel Dave, Kristian Finlator, Eiichi Egami
University of Western Ontario: Pauline Barmby
Imperial College, London: Kirpal Nandra
University of Chicago/KICP: Brandt Robertson
Swinburne University: Darren Croton
Stanford University/KIPAC: Risa Wechsler
University of Florida, Gainesville: Vicki Sarajedini
Astrophysikalisches Institute, Potsdam: Andrea Cattaneo
University of Massachusetts, Amherst: Houjun Mo
Royal Observatory Edinburgh: James Dunlop
Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan: Lihwai Lin
National Research Council, Herzberg Institute of Astrophysics: Luc Simard
Texas A&M University: Casey Papovich
Tohoku University, Japan: Toru Yamada
Oxford University: Dimitra RigopoulouUniversity of California, Riverside: Gillian Wilson
SEDS Co-Investigators
SEDS: Scientific Objectives
• Galaxy Assembly in the Early Universe
– Direct study of the mass assembly back to the era of reionization.• Study stellar masses and mass functions from z = 4 - 6• Constrain high mass end of mass function at z = 7.
– Measurement of spatial clustering of galaxies• Determine the evolution of galaxy properties as a function of halo masses.
– Study of identified Ly emitters at z = 5 - 7.• High z counterparts to dwarf galaxies?• Different sample compared to dropouts
– Black hole evolution at z > 6.• Study of high-z AGN number counts (constrain evolutionary models)• Relationship to stellar growth
– Tests of theoretical models of galaxy assembly• Numerical simulation models to tie observational effects together
SEDS: Scientific Objectives
• Auxiliary Science– Galaxy Evolution from z ~ 1 - 4
• Nature of high-z galaxies• Mass assembly of galaxies• Emergence of quiescent galaxies
– Mid-infrared Variability for AGN Identification• A more universal tracer of AGN
– Measurement of the Cosmic Infrared Background radiation spatial fluctuations
SEDS: Technical Aspects
• Sensitivity– 12 hrs/pointing at 3.6 and 4.5 microns
– [3.6] = 26 AB, 5 (0.15 Jy)
– Robustly measure M* (reach 5 x 109 Msun at z = 6)
• Field Geometry and Configuration– Clustering and large scale structure at z = 6: > 20 - 30 arcmin
– Correlation length: > 5 - 10 arcmin
• Number of Fields– Cosmic variance: 5 fields
• Field Selection– Fields with deep auxiliary data: Extended GOODS-S, Extended
GOODS-N, UDS, EGS, COSMOS/UltraVista
SEDS Survey Fields
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are needed to see this picture.
Area Coverage vs Exposure Time
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SEDS: Technical Aspects
• Expected Number of Sources– Statistically meaningful samples– Enough to derive mass functions and perform
clustering studies– Finlator models: 8000, 2000, and 200 at z = 5, 6,
and 7; few at z ~ 9.
• Source Selection– Conventional Ly “dropout” technique
• Z = 4, 5, 6, and 7: B, V, i, and z
Timeline of Warm Mission EventsOriginal IWIC plan affected by unexpected thermal control issues. Significant delay while reworking IRAC thermal control system.• Cryogen exhausted 15 May 2009 22:11:27 UTC
• IRAC Warm Instrument Characterization (IWIC) begins 19 May 2009- Anomaly with IRAC thermal control Standby mode entry 19 May 2009 23:35:48- Observatory returned to normal mode 20 May 2009- Firmware patch initiated- Transition science (GRB image) and instrument characterization during patch development
• Firmware patched and IWIC restarted 19 June 2009 - Temperature setpoint of 31 K and applied bias of 450 mV selected 03 July
• IWIC completed 28 July 2009
It became apparent that the IRAC heaters were driving the MIC temperature higher than power-off equilibrium.
Timeline of Warm Mission Events
• 12 Aug 2009 -- array heaters switched off– Permitted operation 1.3 K cooler than original setpoint; critical noise
boundary
• 18 Sep 2009 -- Final operating setpoints established– 500 mV applied bias, T(array) = 28.7 K; final MIC temperature expected
to be 27.5K
• 23-30 Sep 2009 Recalibration sequence conducted– Flat-field, linearity, bias, photometric calibrations
• 29 Sep 2009 -- First campaign 2 wks of data released to observers• 12 Oct 2009 -- 6th campaign released back on normal 14 day after
campaign ends release cadence
• Bad surprises- Linearity very different than cryogenic- Appearance of intermediate term latents- Column pulldown slightly more complicated
Good surprises- No long term latents at 3.6 m- No muxbleed and muxstripe- We have not derived the first-frame correction yet, but have the data in hand
• As expected- Optical performance remains the same- 3.6 and 4.5 m performance close to cryogenic- AOT worked as expected- Pipeline performed as in cryogenic mission
IWIC calibration and characterization of greater depth and complexity of the IRAC characterization during the original In-Orbit Checkout
Spitzer Warm MissionVariances from the Expected
Warm IRAC Performance
• Deep image noise performance– From dark measurements – 3.6 m 12% worse than cryo– 4.5 m 10% better than cryo – 10% uncertainty in values
• Bright source limit– S/N ~ (throughput)0.5 – 3.6 m 5% lower than cryo – 4.5 m 2% lower than cryo
Absolute Calibration– Currently 5% absolute calibration
uncertainty compared to 3% at end of cryo mission
• Performance supports all warm mission science
Data Calibration
Instrument calibration load down to about 4% of total observing time.Flatfield – currently recalibrated to better than cryo (0.2%).
Darks – recalibrated similarly to cryo. More sturcture than previously, but subtracts well.
Linearization – calibrated at 5% level, difficult to measure, but plan to solve this is underway.
Flux Calibration – currently at few % level, will get better with time as routine calibrations build.
First-Frame Effect – data taken, effect is relatively small for the InSb.
Pixel-Phase Correction – larger than cryo, but significant characterization data taken.
Warm vs. Cryogenic: Deep Imaging of EGS
Warm 3.6 m Cryo 3.6 m
Warm 4.5 m Cryo 4.5 m
5 UDS Field (20 x 20 arcmin)
3.6 micron 4.5 micron
UDS Field (5 x 5 arcmin)
3.6 micron 4.5 micron
NGC 2899NGC 4361
Planetary Nebulae
Cygnus DR22
Star-Forming Regions
• Warm IRAC sensitivity comparable to cryogenic
• IRAC data quality / sensitivity support all current and planned warm science
• Pipelines functional (absolute calibration currently ~5%)
• Science quality data flowing to the community
• Continuing analysis (linearity, bias, absolute calibration) will improve data quality
• Anticipate update to warm calibration and data reprocessing by first of year
• Currently completed one epoch of SEDS data: UDS field (4 hrs)
• Next SEDS observations: EGS and COSMOS/UltraVista
Summary