A systematic survey for z < 0.04 CLAGNs
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Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Astronomical Society
Abstract
We have conducted a systematic survey for z < 0.04 active Galactic nuclei (AGNs) that may have changed spectral class over
the past decade. We use SkyMapper, Pan-STARRS and the V´eron-Cetty & V´eron catalogue to search the entire sky for these
‘changing-look’ AGNs (CLAGNs) using a variety of selection methods, where Pan-STARRS has a coverage of 3π steradians
(sky north of Declination −30◦) and SkyMapper has coverage of ∼21000 deg2 (sky south of Declination 0◦). We use small
aperture photometry to measure how colour and flux have changed over time, where a change may indicate a change in spectral
type. Optical colour and flux are used as a proxy for changing Hα equivalent width, while WISE 3.4 μm flux is used to look
for changes in the hot dust component. We have identified four AGNs with varying spectra selected using our optical colour
selection method. Three AGNs were confirmed from recent observations with WiFeS on the 2.3 m telescope at Siding Spring
and the other was identified from archival spectra alone. From this, we identify two new CLAGNs; NGC 1346 and 2MASX
J20075129–1108346.We also recover Mrk 915 and Mrk 609, which are known to have varying spectra in the literature, but they
do not meet our specific criteria for CLAGNs.
Description
Keywords
methods, Observational – galaxies, active – galaxies, Seyfert
Citation
Senarath, M. R., Brown, M. J., Cluver, M. E., Jarrett, T. H., Wolf, C., Ross, N. P., Lucey, J. R., Parkash, V., & Hon, W. J. (2021). A systematic survey for z< 0.04 clagns. Monthly Notices of the Royal Astronomical Society, 503(2), 2583–2597. https://doi.org/10.1093/mnras/stab393