Further observational evidence for a critical ionizing luminosity in active galaxies
We report the results of a survey for H I 21-cm absorption at redshifts of z ≳ 2.6 in a new sample of radio sources with the Green Bank and Giant Metrewave Radio Telescopes. From a total of 25 targets, we report zero detections in the 16 for which optical depth limits could be obtained. Based upon t...
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
Oxford University Press
2017
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| _version_ | 1797093816829739008 |
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| author | Curran, S Hunstead, R Johnston, H Whiting, M Sadler, E Allison, J Bignell, C |
| author_facet | Curran, S Hunstead, R Johnston, H Whiting, M Sadler, E Allison, J Bignell, C |
| author_sort | Curran, S |
| collection | OXFORD |
| description | We report the results of a survey for H I 21-cm absorption at redshifts of z ≳ 2.6 in a new sample of radio sources with the Green Bank and Giant Metrewave Radio Telescopes. From a total of 25 targets, we report zero detections in the 16 for which optical depth limits could be obtained. Based upon the detection rate for z ≥ 0.1 associated absorption, we would expect approximately four detections. Of the 11 which have previously not been searched, there is sufficient source-frame optical/ultraviolet photometry to determine the ionizing photon rate for four. Adding these to the literature, the hypothesis that there is a critical rate of QHI∼1056 ionizing photons per second (a monochromatic λ = 912 Å luminosity of LUV ∼ 1023 W Hz−1) is now significant at ≈7σ. This reaffirms our assertion that searching z ≳ 3 active galaxies for which optical redshifts are available selects sources in which the ultraviolet luminosity is sufficient to ionize all of the neutral gas in the host galaxy. |
| first_indexed | 2024-03-07T04:05:38Z |
| format | Journal article |
| id | oxford-uuid:c60b1edc-141f-4a4d-9f82-41681ff34669 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:05:38Z |
| publishDate | 2017 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | oxford-uuid:c60b1edc-141f-4a4d-9f82-41681ff346692022-03-27T06:35:20ZFurther observational evidence for a critical ionizing luminosity in active galaxiesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:c60b1edc-141f-4a4d-9f82-41681ff34669EnglishSymplectic Elements at OxfordOxford University Press2017Curran, SHunstead, RJohnston, HWhiting, MSadler, EAllison, JBignell, CWe report the results of a survey for H I 21-cm absorption at redshifts of z ≳ 2.6 in a new sample of radio sources with the Green Bank and Giant Metrewave Radio Telescopes. From a total of 25 targets, we report zero detections in the 16 for which optical depth limits could be obtained. Based upon the detection rate for z ≥ 0.1 associated absorption, we would expect approximately four detections. Of the 11 which have previously not been searched, there is sufficient source-frame optical/ultraviolet photometry to determine the ionizing photon rate for four. Adding these to the literature, the hypothesis that there is a critical rate of QHI∼1056 ionizing photons per second (a monochromatic λ = 912 Å luminosity of LUV ∼ 1023 W Hz−1) is now significant at ≈7σ. This reaffirms our assertion that searching z ≳ 3 active galaxies for which optical redshifts are available selects sources in which the ultraviolet luminosity is sufficient to ionize all of the neutral gas in the host galaxy. |
| spellingShingle | Curran, S Hunstead, R Johnston, H Whiting, M Sadler, E Allison, J Bignell, C Further observational evidence for a critical ionizing luminosity in active galaxies |
| title | Further observational evidence for a critical ionizing luminosity in active galaxies |
| title_full | Further observational evidence for a critical ionizing luminosity in active galaxies |
| title_fullStr | Further observational evidence for a critical ionizing luminosity in active galaxies |
| title_full_unstemmed | Further observational evidence for a critical ionizing luminosity in active galaxies |
| title_short | Further observational evidence for a critical ionizing luminosity in active galaxies |
| title_sort | further observational evidence for a critical ionizing luminosity in active galaxies |
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