Swift detection of the NLS1 galaxy Mkn 335 in a high X-ray flux state

ATel #14717; Dirk Grupe (Morehead State University), S. Komossa (MPIfR), Luigi Gallo (St. Mary's University), and Erin Kara (MIT)
on 15 Jun 2021; 13:07 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)

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We report on the Swift detections of repeated X-ray flaring of the Narrow-Line Seyfert 1 (NLS1) galaxy Mkn 335 (RA-2000=00h06m19.5s, Dec-2000=+20d12m11s) after we resumed our regular monitoring campaign on May 19 after the AGN emerged from Swift Sun-constraint. Our latest 1 ks Swift observation was performed on 2020-June-14 starting at 03:59 UT and showed Mkn 335 at a 0.3-10 keV flux level of (1.4+/-0.1)e-15 W m^-2 (1.7e-15 W m^-2 after correction for Galactic absorption). The X-ray spectral slope was alpha_x=1.28+/-0.13 or Gamma_x=2.28+/-0.13. This flux is about a factor of 2 higher than the highest flux detected during the 2020 May/June flaring period (ATel #13757; Komossa et al., 2020, A&A 643, L7) and a factor of more than 10 larger than during the 2018/2019 low state (Parker et al. 2019). Although Mkn 335 is very active in X-rays, it does not show a similar flaring in the optical/UV band. The fluxes in the optical/UV have remained more constant after Mkn 335 emerged from the Sun-constraint and only show low-amplitude variability. We will continue with daily Swift observations. Also currently XMM and NuSTAR are observing Mkn 335. We would like to encourage optical observers to obtain optical spectra to look for any changes in the high-ionization emission lines especially from the BLR. At previous epochs, the high-ionization lines did not follow the high-amplitude X-ray variability we detected, implying that the emisssion lines saw a different continuum than the observer in x-rays (Komossa et al. 2020). We would like to thank Brad Cenko for approving our current monitoring campaigns and the Swift team for starting the observations right away when Mkn 335 came out of the sun-constraint.