Clues to active galactic nucleus growth from optically variable objects in the hubble ultra deep field

S. H. Cohen, R. E. Ryan, A. N. Straughn, N. P. Hathi, Rogier Windhorst, A. M. Koekemoer, N. Pirzkal, C. Xu, B. Mobasher, S. Malhotra, L. G. Strolger, J. E. Rhoads

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We present a photometric search for objects with point-source components that are optically variable on timescales of weeks to months in the Hubble Ultra Deep Field (HUDF) to i′AB = 28.0 mag. The data are split into four substacks of approximately equal exposure times. Objects exhibiting the signature of optical variability are selected by studying the photometric error distribution between the four different epochs and selecting 622 candidates as 3.0 σ outliers from the original catalog of 4644 objects. Of these, 45 are visually confirmed as free of contamination from close neighbors or various types of image defects. Four lie within the positional error boxes of Chandra X-ray sources, and two of these are spectroscopically confirmed AGNs. The photometric redshift distribution of the selected variable sample is compared to that of field galaxies, and we find that a constant fraction of ∼1% of all field objects show variability over the range of 0.1 ≲ z ≲ 4.5. Combined with other recent HUDF results, as well as those of recent state-of-the-art numerical simulations, we discuss a potential link between the hierarchical merging of galaxies and the growth of AGNs.

Original languageEnglish (US)
Pages (from-to)731-739
Number of pages9
JournalAstrophysical Journal
Volume639
Issue number2 I
DOIs
StatePublished - Mar 10 2006

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active galactic nuclei
galaxies
outlier
point sources
catalogs
point source
defect
boxes
contamination
time measurement
signatures
timescale
defects
simulation
x rays
distribution
state of the art
exposure

Keywords

  • Black hole physics
  • Galaxies: active
  • Galaxies: formation
  • Galaxies: nuclei

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Cohen, S. H., Ryan, R. E., Straughn, A. N., Hathi, N. P., Windhorst, R., Koekemoer, A. M., ... Rhoads, J. E. (2006). Clues to active galactic nucleus growth from optically variable objects in the hubble ultra deep field. Astrophysical Journal, 639(2 I), 731-739. https://doi.org/10.1086/499577

Clues to active galactic nucleus growth from optically variable objects in the hubble ultra deep field. / Cohen, S. H.; Ryan, R. E.; Straughn, A. N.; Hathi, N. P.; Windhorst, Rogier; Koekemoer, A. M.; Pirzkal, N.; Xu, C.; Mobasher, B.; Malhotra, S.; Strolger, L. G.; Rhoads, J. E.

In: Astrophysical Journal, Vol. 639, No. 2 I, 10.03.2006, p. 731-739.

Research output: Contribution to journalArticle

Cohen, SH, Ryan, RE, Straughn, AN, Hathi, NP, Windhorst, R, Koekemoer, AM, Pirzkal, N, Xu, C, Mobasher, B, Malhotra, S, Strolger, LG & Rhoads, JE 2006, 'Clues to active galactic nucleus growth from optically variable objects in the hubble ultra deep field', Astrophysical Journal, vol. 639, no. 2 I, pp. 731-739. https://doi.org/10.1086/499577
Cohen, S. H. ; Ryan, R. E. ; Straughn, A. N. ; Hathi, N. P. ; Windhorst, Rogier ; Koekemoer, A. M. ; Pirzkal, N. ; Xu, C. ; Mobasher, B. ; Malhotra, S. ; Strolger, L. G. ; Rhoads, J. E. / Clues to active galactic nucleus growth from optically variable objects in the hubble ultra deep field. In: Astrophysical Journal. 2006 ; Vol. 639, No. 2 I. pp. 731-739.
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