Host galaxy magnitude of OJ 287 from its colours at minimum light

Abstract

OJ 287 is a BL Lacertae type quasar in which the active galactic nucleus (AGN) outshines the host galaxy by an order of magnitude. The only exception to this may be at minimum light when the AGN activity is so low that the host galaxy may make quite a considerable contribution to the photometric intensity of the source. Such a dip or a fade in the intensity of OJ 287 occurred in November 2017, when its brightness was about 1.75 magnitudes lower than the recent mean level. We compare the observations of this fade with similar fades in OJ 287 observed earlier in 1989, 1999, and 2010. It appears that there is a relatively strong reddening of the B$-$V colours of OJ 287 when its V-band brightness drops below magnitude 17. Similar changes are also seen V$-$R, V$-$I, and R$-$I colours during these deep fades. These data support the conclusion that the total magnitude of the host galaxy is $V=18.0\pm 0.3$, corresponding to $M_K=-26.5\pm 0.3$ in the K-band. This is in agreement with the results, obtained using the integrated surface brightness method, from recent surface photometry of the host. These results should encourage us to use the colour separation method also in other host galaxies with strongly variable AGN nuclei. In the case of OJ 287, both the host galaxy and its central black hole are among the biggest known, and its position in the black hole mass-galaxy mass diagram lies close to the mean correlation.

8 pages, 4 figures, accepted for publication in MNRAS

References in corpus (4)

• The Carnegie-Irvine Galaxy Survey. III. The Three-Component Structure of Nearby Elliptical Galaxies
• Explaining temporal variations in the jet position angle of the blazar OJ 287 using its binary black hole central engine model
• MOMO IV: The complete Swift X-ray and UV/optical light curve and characteristic variability of the blazar OJ 287 during the last two decades
• Stellar dynamics in the strong-lensing central galaxy of Abell 1201: A low stellar mass-to-light ratio, a large central compact mass, and a standard dark matter halo

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• On the need of an ultramassive black hole in OJ 287
• Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey