Steep functions in astronomy: the RQSO z-cutoff debate
| dc.creator | Wall, J. V. | |
| dc.date | 2006-10-06 | |
| dc.date.accessioned | 2026-07-07T07:26:52Z | |
| dc.date.available | 2026-07-07T07:26:52Z | |
| dc.description | Astronomers traditionally find steep, open-ended functions difficult: the log N - log S curve for example, or the probability-area-radius relation in making cross-waveband identifications. The debate over the existence of a redshift cutoff for RQSOs (radio-loud QSOs; Jarvis and Rawlings 2000, Wall et al. 2005) is a case in point: an instance in which a second-order effect involving radio-variable QSOs, initially selected by survey from a population with a steep source count, leads to discrepant results from different analyses. A redshift cutoff is present in optically-selected QSOs of the SDSS and in X-ray selected QSOs of XMM, ROSAT and CHANDRA. A similar cutoff for radio-loud QSOs is important to establish, because if present, no known type of obscuration can be responsible. Such a space-density diminution then defines an epoch of creation for galaxy hosts of massive black holes powering AGN, a datum for galaxy formation. I discuss the resolution of the debate: the issue is highly relevant to modern surveys and their follow-up observations. | |
| dc.description | Presented at 'Statistical Challenges in Modern Astronomy - IV', Penn State, May 2006; to appear in the conference proceedings edited by G. J. Babu and E. D. Feigelson, 2 pages, 2 figures | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0610216 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0610216 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/117181 | |
| dc.subject | Astrophysics | |
| dc.title | Steep functions in astronomy: the RQSO z-cutoff debate | |
| dc.type | text |