MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS
Calibrating the photometric redshifts of ≳10[superscript 9] galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths...
| Main Authors: | , , , , , , , , , , , , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2016
|
| Online Access: | http://hdl.handle.net/1721.1/100755 |
| _version_ | 1826201074275450880 |
|---|---|
| author | Masters, Daniel Capak, Peter Stern, Daniel Ilbert, Olivier Salvato, Mara Schmidt, Samuel Longo, Giuseppe Rhodes, Jason Paltani, Stephane Mobasher, Bahram Hoekstra, Henk Hildebrandt, Hendrik Coupon, Jean Steinhardt, Charles Speagle, Josh Faisst, Andreas Brodwin, Mark Brescia, Massimo Cavuoti, Stefano Kalinich, Adam O. |
| author2 | Massachusetts Institute of Technology. Department of Mathematics |
| author_facet | Massachusetts Institute of Technology. Department of Mathematics Masters, Daniel Capak, Peter Stern, Daniel Ilbert, Olivier Salvato, Mara Schmidt, Samuel Longo, Giuseppe Rhodes, Jason Paltani, Stephane Mobasher, Bahram Hoekstra, Henk Hildebrandt, Hendrik Coupon, Jean Steinhardt, Charles Speagle, Josh Faisst, Andreas Brodwin, Mark Brescia, Massimo Cavuoti, Stefano Kalinich, Adam O. |
| author_sort | Masters, Daniel |
| collection | MIT |
| description | Calibrating the photometric redshifts of ≳10[superscript 9] galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST. |
| first_indexed | 2024-09-23T11:45:53Z |
| format | Article |
| id | mit-1721.1/100755 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:45:53Z |
| publishDate | 2016 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1007552022-09-27T21:47:07Z MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS Masters, Daniel Capak, Peter Stern, Daniel Ilbert, Olivier Salvato, Mara Schmidt, Samuel Longo, Giuseppe Rhodes, Jason Paltani, Stephane Mobasher, Bahram Hoekstra, Henk Hildebrandt, Hendrik Coupon, Jean Steinhardt, Charles Speagle, Josh Faisst, Andreas Brodwin, Mark Brescia, Massimo Cavuoti, Stefano Kalinich, Adam O. Massachusetts Institute of Technology. Department of Mathematics Kalinich, Adam O. Calibrating the photometric redshifts of ≳10[superscript 9] galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST. 2016-01-07T16:56:44Z 2016-01-07T16:56:44Z 2015-10 Article http://purl.org/eprint/type/JournalArticle 1538-4357 0004-637X http://hdl.handle.net/1721.1/100755 Masters, Daniel, Peter Capak, Daniel Stern, Olivier Ilbert, Mara Salvato, Samuel Schmidt, Giuseppe Longo, et al. “MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS.” The Astrophysical Journal 813, no. 1 (October 28, 2015): 53. © 2015 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637x/813/1/53 The Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing IOP Publishing |
| spellingShingle | Masters, Daniel Capak, Peter Stern, Daniel Ilbert, Olivier Salvato, Mara Schmidt, Samuel Longo, Giuseppe Rhodes, Jason Paltani, Stephane Mobasher, Bahram Hoekstra, Henk Hildebrandt, Hendrik Coupon, Jean Steinhardt, Charles Speagle, Josh Faisst, Andreas Brodwin, Mark Brescia, Massimo Cavuoti, Stefano Kalinich, Adam O. MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS |
| title | MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS |
| title_full | MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS |
| title_fullStr | MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS |
| title_full_unstemmed | MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS |
| title_short | MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS |
| title_sort | mapping the galaxy color redshift relation optimal photometric redshift calibration strategies for cosmology surveys |
| url | http://hdl.handle.net/1721.1/100755 |
| work_keys_str_mv | AT mastersdaniel mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT capakpeter mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT sterndaniel mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT ilbertolivier mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT salvatomara mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT schmidtsamuel mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT longogiuseppe mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT rhodesjason mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT paltanistephane mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT mobasherbahram mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT hoekstrahenk mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT hildebrandthendrik mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT couponjean mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT steinhardtcharles mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT speaglejosh mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT faisstandreas mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT brodwinmark mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT bresciamassimo mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT cavuotistefano mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys AT kalinichadamo mappingthegalaxycolorredshiftrelationoptimalphotometricredshiftcalibrationstrategiesforcosmologysurveys |