NOAO >   Observing Info >   Approved Programs >   2017A-0252

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Program Information for 2017A-0252


PI: Helene Flohic, University of the Pacific, ln.flohic@gmail.com
Address: Physics Department, 3601 Pacific Avenue, Stockton, CA 95211 United States

CoI: Mike Eracelous, Pennsylvania State U.
CoI: Jessie Runnoe, U. of Michigan
CoI: Chelsea Macleod, Harvard-Smithsonian Center for Astrophysics
CoI: Paul J Green, Harvard-Smithsonian Center for Astrophysics
CoI: John Ruan, U. of Washington
CoI: Scott Anderson, U. of Washington
CoI: Johnson Liu, University of the Pacific

Title: Testing models for the nature of changing-look quasars through the long- term behavior of their narrow lines

Abstract: We request spectroscopic observations of three changing-look quasars to test different explanations for the observed extreme variability of the continuum and broad emission lines of these objects. By monitoring the flux ratio of the narrow emission lines, we will test whether the disappearance of the continuum is due to obscuration or to intrinsic dimming of the ionizing continuum. In the former scenario the relative intensities of the narrow lines would stay constant, while in the latter they would vary. The nature and timescale of the line ratio variability (in the case of intrinsic dimming) would depend on the structure of the narrow line region (NLR). Thus observing varying narrow-line ratios would also allow us to constrain the density structure of the NLR. The spectra we propose to obtain here will be included in a larger data set, used to monitor the continuum level and broad emission-line strengths, in order to test other hypotheses that invoke a nuclear transient (tidal disruption event or supernova). This proposal is part of a larger effort to monitor changing-look quasars over long time scales. Thus, we propose to use the KPNO 4m for the brighter targets in our sample, while reserving the fainter ones for bigger telescopes.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2017A):  KP-4m/KOSMOS -- 2n on Jul 19 - Jul 20 2017


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2017A-0252

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