Optical Spectroscopy of Active Galactic Nuclei in SA57

Abstract

The cosmological evolution of X-ray-selected and optically selected Active Galactic Nuclei (AGNs) show different behaviours interpreted in terms of two different populations. The difference is evident mainly for low luminosity AGNs (LLAGNs), many of which are lost by optical photometric surveys. We are conducting a spectroscopical study of a composite sample of AGN candidates selected in SA57 following different searching techniques, to identify low luminosity AGNs and break down the sample into different classes of objects. AGN candidates were obtained through optical variability and/or X-ray emission. Of special interest are the extended variable objects, which are expected to be galaxies hosting LLAGNs. Among the 26 classified objects a fair number (9) show typical AGN spectra. 10 objects show Narrow Emission Line Galaxy spectra, and in most of them (8/10) optical variability suggests the presence of LLAGNs.

7 pages, 8 figures, to appear in A&A

References in corpus (26)

• Cosmological Evolution of the Hard X-ray AGN Luminosity Function and the Origin of the Hard X-ray Background
• The Ensemble Photometric Variability of ~25000 Quasars in the Sloan Digital Sky Survey
• The Spectral Energy Distributions of Low-Luminosity Active Galactic Nuclei
• The HELLAS2XMM survey. VII. The hard X-ray luminosity function of AGN up to z=4: more absorbed AGN at low luminosities and high redshifts
• The evolution of faint AGN between z~1 and z~5 from the COMBO-17 survey
• The Murmur of the Sleeping Black Hole: Detection of Nuclear Ultraviolet Variability in LINER Galaxies
• The HELLAS2XMM survey: II. Multiwavelength observations of P3: an X-ray bright, optically inactive galaxy
• Structure Function Analysis of Long Term Quasar Variability
• The Nature of X-ray Bright Optically Normal Galaxies
• The VVDS type-1 AGN sample: The faint end of the luminosity function
• Low-Luminosity Active Galactic Nuclei: Are They UV-Faint and Radio Loud?
• Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields
• Stellar Population in LLAGN.I: Ground-based observations
• The Ensemble Variability Properties of Faint QSOs
• Why X-ray--Selected AGN Appear Optically Dull
• Spectroscopic identification of ten faint hard X-ray sources discovered by Chandra
• The Central Engines of 19 LINERs as Viewed by Chandra
• Chandra-SDSS Normal and Star-Forming Galaxies I: X-ray Source Properties of Galaxies Detected by Chandra in SDSS DR2
• A V-Band Survey for Variable Galactic Nuclei in the Hubble Deep Field
• Variable Extended Objects in SA 57
• X-ray Bright Optically Inactive Galaxies (XBONG) in XMM-Newton/SDSS fields: more diluted than absorbed?
• Chandra Observations of Candidate "True" Seyfert 2 Nuclei
• The DEEP Groth Strip Survey VI. Spectroscopic, Variability, and X-ray Detection of AGN
• Optical Variability of Infrared Power Law-Selected Galaxies & X-ray Sources in the GOODS-South Field
• Bimodal AGNs in Bimodal Galaxies
• An X-ray Survey in SA 57 with XMM-Newton

Cited by in corpus (4)

• Variability-selected active galactic nuclei from supernova search in the Chandra deep field south
• Spectroscopic follow-up of variability-selected active galactic nuclei in the Chandra Deep Field South
• Continuum optical-UV and X-ray variability of AGN: current results and future challenges
• The XMM Deep Survey in the CDF-S VII. UV catalogue of the Optical Monitor observations