THE CHANDRA SURVEY OF THE COSMOS FIELD. II. SOURCE DETECTION AND PHOTOMETRY

Journal Article · Tue Dec 01 00:00:00 EST 2009 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/185/2/586; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21301469

Puccetti, S ^[1]; Vignali, C ^[2]; Cappelluti, N; Brunner, H; Brusa, M; Fruscione, A; Finoguenov, A ^[3]; Fiore, F ^[4]; Zamorani, G; Gilli, R; Comastri, A ^[5]; Aldcroft, T L; Elvis, M; Civano, F ^[6]; Miyaji, T ^[7]; Damiani, F ^[8]; Koekemoer, A M ^[9]

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1. ASI Science Data Center, via Galileo Galilei, 00044 Frascati (Italy)
2. Dipartimento di Astronomia, Universita di Bologna, via Ranzani 1, Bologna (Italy)
3. Max Planck Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei Muenchen (Germany)
4. INAF-OAR, via Frascati 33, Monteporzio, I00040 (Italy)
5. INAF, Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
6. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)
7. Instituto de AstronomIa, Universidad Nacional Autonoma de Mexico, Ensenada, Mexico (Mexico)
8. INAF, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)
9. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that covers the central contiguous {approx}0.92 deg{sup 2} of the COSMOS field. C-COSMOS is the result of a complex tiling, with every position being observed in up to six overlapping pointings (four overlapping pointings in most of the central {approx}0.45 deg{sup 2} area with the best exposure, and two overlapping pointings in most of the surrounding area, covering an additional {approx}0.47 deg{sup 2}). Therefore, the full exploitation of the C-COSMOS data requires a dedicated and accurate analysis focused on three main issues: (1) maximizing the sensitivity when the point-spread function (PSF) changes strongly among different observations of the same source (from {approx}1 arcsec up to {approx}10 arcsec half-power radius); (2) resolving close pairs; and (3) obtaining the best source localization and count rate. We present here our treatment of four key analysis items: source detection, localization, photometry, and survey sensitivity. Our final procedure consists of a two step procedure: (1) a wavelet detection algorithm to find source candidates and (2) a maximum likelihood PSF fitting algorithm to evaluate the source count rates and the probability that each source candidate is a fluctuation of the background. We discuss the main characteristics of this procedure, which was the result of detailed comparisons between different detection algorithms and photometry tools, calibrated with extensive and dedicated simulations.

• OSTI ID: 21301469
• Journal Information: Astrophysical Journal, Supplement Series, Vol. 185, Issue 2; Other Information: DOI: 10.1088/0067-0049/185/2/586; Country of input: International Atomic Energy Agency (IAEA); ISSN 0067-0049
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALGORITHMS
COSMOLOGY
COUNTING RATES
DATA ANALYSIS
MAXIMUM-LIKELIHOOD FIT
PHOTOMETRY
PROBABILITY
SENSITIVITY
SIMULATION
UNIVERSE