研究目的
To discover and characterize distant galaxy (proto-)clusters at high redshifts (z > 1.5) by identifying overdensities of galaxies with high star-formation rates using multi-wavelength data from Planck, Herschel, and Spitzer.
研究成果
The SPHerIC survey successfully identifies candidate galaxy (proto-)clusters at high redshifts with high star-formation rates. The overdensities are significant and suggest that these are massive structures, likely progenitors of today's most massive clusters. Spectroscopic follow-up is needed for confirmation and deeper understanding.
研究不足
The study relies on photometric data without spectroscopic confirmation, leading to uncertainties in redshift estimates (Δzp ~ 0.7) and potential contamination from chance alignments. The assumption that the brightest red SPIRE source is the center of overdensities may not always hold, and the sample may include lensed systems or other contaminants. The mass estimates are approximate and could be overestimated for non-virialized protoclusters.
1：Experimental Design and Method Selection:
The survey uses a two-step process: first, Planck data is used to select sources with high star-formation rates based on color criteria; second, Herschel data provides higher resolution to separate individual sources. Spitzer/IRAC observations are then used to detect and analyze the stellar content and overdensities. Methods include source extraction with SExtractor, aperture photometry, and density mapping.
2：Sample Selection and Data Sources:
The sample consists of 82 galaxy (proto-)cluster candidates selected from Planck and Herschel observations, focusing on sources with high star-formation rates and specific color cuts (e.g., [3.6]-[4.5] > -0.1 for IRAC red sources). Data sources include Planck, Herschel, and Spitzer space telescopes.
3：6]-[5] > -1 for IRAC red sources). Data sources include Planck, Herschel, and Spitzer space telescopes.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Instruments used are the Planck satellite (High Frequency Instrument), Herschel Space Observatory (SPIRE instrument), and Spitzer Space Telescope (IRAC instrument).
4：Experimental Procedures and Operational Workflow:
Observations involve taking IRAC images at 3.6 and 4.5 microns with specific integration times and dither patterns. Data reduction includes creating mosaics, source extraction, photometry with aperture corrections, and noise characterization.
5：6 and 5 microns with specific integration times and dither patterns. Data reduction includes creating mosaics, source extraction, photometry with aperture corrections, and noise characterization.
Data Analysis Methods:
5. Data Analysis Methods: Analysis includes estimating surface densities of red sources, comparing with control fields (e.g., SpUDS), photometric redshift estimation, and mass estimation using richness-mass relations.
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