Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs
Gravitational lensing by massive galaxy clusters enables faint distant galaxies to be more abundantly detected than in blank fields, thereby allowing one to construct galaxy luminosity functions (LFs) to an unprecedented depth at high redshifts. Intriguingly, photometric redshift catalogs constructe...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/add7d5 |
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| author | Jiashuo Zhang Jeremy Lim Tom Broadhurst Sung Kei Li Man Cheung Li Giorgio Manzoni Rogier Windhorst |
| author_facet | Jiashuo Zhang Jeremy Lim Tom Broadhurst Sung Kei Li Man Cheung Li Giorgio Manzoni Rogier Windhorst |
| author_sort | Jiashuo Zhang |
| collection | DOAJ |
| description | Gravitational lensing by massive galaxy clusters enables faint distant galaxies to be more abundantly detected than in blank fields, thereby allowing one to construct galaxy luminosity functions (LFs) to an unprecedented depth at high redshifts. Intriguingly, photometric redshift catalogs constructed from the Hubble Frontier Fields survey display an excess of z ≳ 4 galaxies in the cluster lensing fields that is not seen in accompanying blank parallel fields. The observed excess, while possibly a gift of gravitational lensing, could also be from misidentified low- z contaminants having similar spectral energy distributions as high- z galaxies. In the latter case, the contaminants may result in nonphysical upturns in UV LFs and/or washed-out faint-end turnovers predicted by contender cosmological models to Lambda cold dark matter (ΛCDM). Here, we employ the concept of magnification bias to perform the first statistical estimation of contamination levels in Hubble Frontier Fields lensing field photometric redshift catalogs. While we were able to reproduce a lower- z lensed sample, it was found ∼56% of the 3.5 < z _phot < 5.5 samples are likely low- z contaminants. Widely adopted Lyman-break-galaxy-like selection rules in the literature may give a “cleaner” sample magnification-bias-wise but we warn readers the resulting sample would also be less complete. Individual mitigation of contaminants is arguably the best way to investigate the faint high- z Universe, and this may be made possible with JWST observations. |
| format | Article |
| id | doaj-art-17fb40b44af246c7805113c4cc50b8ea |
| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-17fb40b44af246c7805113c4cc50b8ea2025-08-20T02:47:59ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01988227910.3847/1538-4357/add7d5Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z CatalogsJiashuo Zhang0https://orcid.org/0000-0002-3783-4629Jeremy Lim1https://orcid.org/0000-0003-4220-2404Tom Broadhurst2https://orcid.org/0000-0002-8785-8979Sung Kei Li3https://orcid.org/0000-0002-4490-7304Man Cheung Li4Giorgio Manzoni5https://orcid.org/0000-0001-8220-2324Rogier Windhorst6https://orcid.org/0000-0001-8156-6281Department of Physics, University of Hong Kong , Hong Kong S.A.R., People’s Republic of China ; jszhang@hku.hk, joshua.z.0211@gmail.comDepartment of Physics, University of Hong Kong , Hong Kong S.A.R., People’s Republic of China ; jszhang@hku.hk, joshua.z.0211@gmail.comDepartment of Physics, University of the Basque Country UPV/EHU , Bilbao, Spain; Donostia International Physics Center (DIPC) , Basque Country, San Sebastián, 20018, Spain; Ikerbasque , Basque Foundation for Science, Bilbao, SpainDepartment of Physics, University of Hong Kong , Hong Kong S.A.R., People’s Republic of China ; jszhang@hku.hk, joshua.z.0211@gmail.comDepartment of Physics, University of Hong Kong , Hong Kong S.A.R., People’s Republic of China ; jszhang@hku.hk, joshua.z.0211@gmail.comJockey Club Institute for Advanced Study, The Hong Kong University of Science and Technology , Hong Kong S.A.R., People’s Republic of ChinaSchool of Earth and Space Exploration, Arizona State University , Tempe, AZ, USAGravitational lensing by massive galaxy clusters enables faint distant galaxies to be more abundantly detected than in blank fields, thereby allowing one to construct galaxy luminosity functions (LFs) to an unprecedented depth at high redshifts. Intriguingly, photometric redshift catalogs constructed from the Hubble Frontier Fields survey display an excess of z ≳ 4 galaxies in the cluster lensing fields that is not seen in accompanying blank parallel fields. The observed excess, while possibly a gift of gravitational lensing, could also be from misidentified low- z contaminants having similar spectral energy distributions as high- z galaxies. In the latter case, the contaminants may result in nonphysical upturns in UV LFs and/or washed-out faint-end turnovers predicted by contender cosmological models to Lambda cold dark matter (ΛCDM). Here, we employ the concept of magnification bias to perform the first statistical estimation of contamination levels in Hubble Frontier Fields lensing field photometric redshift catalogs. While we were able to reproduce a lower- z lensed sample, it was found ∼56% of the 3.5 < z _phot < 5.5 samples are likely low- z contaminants. Widely adopted Lyman-break-galaxy-like selection rules in the literature may give a “cleaner” sample magnification-bias-wise but we warn readers the resulting sample would also be less complete. Individual mitigation of contaminants is arguably the best way to investigate the faint high- z Universe, and this may be made possible with JWST observations.https://doi.org/10.3847/1538-4357/add7d5Catalogs |
| spellingShingle | Jiashuo Zhang Jeremy Lim Tom Broadhurst Sung Kei Li Man Cheung Li Giorgio Manzoni Rogier Windhorst Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs The Astrophysical Journal Catalogs |
| title | Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs |
| title_full | Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs |
| title_fullStr | Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs |
| title_full_unstemmed | Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs |
| title_short | Magnification Bias Reveals Severe Contamination in Hubble Frontier Field Photo-z Catalogs |
| title_sort | magnification bias reveals severe contamination in hubble frontier field photo z catalogs |
| topic | Catalogs |
| url | https://doi.org/10.3847/1538-4357/add7d5 |
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