Discovery of the Galaxy Proximity Effect and Implications for Measurements of the Ionizing Background Radiation at Low Redshifts
| Autor: | Sebastian M. Pascarelle, Kenneth M. Lanzetta, Hsiao-Wen Chen, John K. Webb |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Physics
QSOS 010504 meteorology & atmospheric sciences Astrophysics (astro-ph) FOS: Physical sciences Flux Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences Spectral line Galaxy Redshift Space and Planetary Science 0103 physical sciences Magnitude (astronomy) Proximity effect (audio) 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences Background radiation |
| Zdroj: | The Astrophysical Journal. 560:101-109 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/322485 |
| Popis: | We present an analysis of galaxy and QSO absorption line pairs toward 24 QSOs at redshifts between z~0.2 and 1 in an effort to establish the relationship between galaxies and absorption lines in physical proximity to QSOs. We demonstrate the existence of a galaxy proximity effect, in that galaxies in the vicinities of QSOs do not show the same incidence and extent of gaseous envelopes as galaxies far from QSOs. We show that the galaxy proximity effect exists to galaxy-QSO velocity separations of ~ 3000 km/s, much larger than the size of a typical cluster (~ 1000 km/s), i.e. it is more comparable to the scale of the sphere of influence of QSO ionizing radiation rather than the scale of galaxy-QSO clustering. This indicates that the QSO ionizing radiation rather than some dynamical effect from the cluster environment is responsible for the galaxy proximity effect. We combine previous findings that (1) many or most Lya absorption lines arise in extended galaxy envelopes, and (2) galaxies cluster around QSOs to show that the magnitude of the Lya forest proximity effect is underestimated. Consequently, determinations of the UV ionizing background intensity using the proximity effect are likely overestimated. We use the galaxy-QSO cross-correlation function measured from our data to estimate the magnitude of this overestimate and find that it could be as high as a factor of 20 at z 26 pages, 3 figures, to appear in ApJ, October 20, 2001 |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|