Light Curves from the Catalina Real-Time Transient Survey of G-hat Galaxies: Is 6dFGS gJ065559.0-404912 a Kardashev Type-III Galaxy?
Abstract
We show long-term light curves from the Catalina Real-Time Transient Survey of 90 galaxies from the G-hat survey of R. L. Griffith, J. T. Wright, et al. and analyzed by M. A. Garrett. We measured photometry for these galaxies in approximately the visual, or V band with the Sextractor tool of the CRTS. Many of these galaxies show light curves constant to within 0.1 magnitudes over the 5-10 years the survey monitored them. Several galaxies, such as NGC 4355 and ESO 400-28, show variability. IRAS F21384-4556 shows continuous variability over 0.4 magnitudes over 3000 days, reminiscent of a quasar. MCG+03-38-076 varies erratically over 2.5 magnitudes and faster than the average 11.5 days between observations. IC 630 shows flaring, although the photometry may be unreliable since it is near the survey's bright limit, although fainter galaxies such as ESO 434-13, 2MASX J00082041+4037560, 2MASX J11185912-4000135, and 6dFGS gJ232610.6-303106 show similar variability. One anonymous galaxy, 6dFGS gJ065559.0-404912 (= 2MASX J06555900-4049122 = Gaia DR2 5563745165460932608) has a light curve that was sampled on average once per 8.2 days for 5.0 years. It shows irregular, aperiodic fadings from V ~ 16.2 by as much as 1.4 magnitudes. These fadings are reminiscent of those of Boyajian's star (KIC 8462852). One possible explanation may be this is a Kardashev Type-III galaxy—but of course the fadings may be natural, for example from stars moving in front of the central engine of this apparently edge-on galaxy, or by variability of the central engine, or by dust, as was the case for Boyajian's star. Another possibility may be that CSDR2 photometry needs to be better understood. Any of these cases would merit continued monitoring and detailed follow-up. The Catalina Sky Survey (CSS) is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The Catalina Real-Time Transient Survey (CRTS) is supported by the U.S. National Science Foundation under grants AST-0909182.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23324242R