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Swift discovers the Seyfert 1 galaxy PG 1149-110 in very low X-ray and UV flux states

ATel #16938; Dirk Grupe (Northern Kentucky University), S. Komossa (MPIfR Bonn, NAOC Beijing), N. Schartel (ESA Madrid)
on 8 Dec 2024; 15:54 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)

Subjects: Optical, Ultra-Violet, X-ray, AGN, Black Hole, Quasar

We report on the Swift discovery of the Seyfert 1.2 galaxy PG 1149-110 (RA=11:52:03.5, Dec=-11:22:24) in an very low flux state in X-rays and in the UV. A Swift observation on 2024-July-10 indicated a low state in X-rays and the UV. PG 1149-110 has shown a steady decrease in its brightness since 2018. We requested a follow-up observation with Swift which was performed on 2024-December-04. This observation confirmed the very low flux states in X-rays and the optical/UV. For the XRT observation the count rate is at a level of 0.03 counts/s, equal to (1.2+/-0.3)e-15 W/m^2 in the 0.3-10 keV band, based on a single power law model of photon index Gamma_x = 1.72+/-0.40 and Galactic foreground absorption of N_H = 3.2e20 cm^-2. This corresponds to a decline by a factor 15 when compared to the previous Swift X-ray high-state detection in November 2010 (at 0.46 counts/s or (1.6+/-0.1)e-14 W/m^2 from a fit with an absorbed power law model with gamma = 1.71+/-0.09).

In our observation on December 04 we found the following observed optical/UV Vega magnitudes of PG 1149-110 of V=15.75+/-0.05, B=16.77+/-0.06, U=16.97+/-0.07, W1=18.25+/-0.17, M2=17.41+/-0.09, and W2=17.85+/-0.12. Note that these values are of the order of 2.7 Vega magnitudes fainter in the UV W2 band than compared with the Swift observation in August 2018 when PG 1149-110 has shown the brightest state in the optical/UV.

We will continue monitoring PG 1149-110 with Swift and prepare to trigger a pre-approved observation with XMM-Newton. We would like to thank Brad Cenko for approving our observing requests and the Swift team for promptly executing these observations. Results presented here are based on a dedicated multi-year search for outburst and low-state AGN we are carrying out with Swift (e.g., Grupe+ 2010, Parker+ 2016, Grupe+ 2019, ATel #16931, review by Komossa & Grupe 2023).