The swift observations of BL Lacertae object 1ES 2344+514

Abstract

We present the results based on the monitoring of the high energy peaked BL Lacertae object 1ES 2344+514 with the satellite Swift during 2005–2015. Our timing study shows that the source was highly variable on longer (weeks-to-months) time-scales with the 0.3–10 keV flux ranging by a factor of 13.3. The flux variability exhibited an erratic character, changing its amplitude and minimum flux level from flare to flare. In some epochs, an X-ray flare was accompanied by enhanced optical-UV activity, although the uncorrelated 0.3–10 keV and lower-frequency variabilities were also often seen. Our target was significantly passive on intra-day timescales compared to other HBLs. The logparabolic distribution of the X-ray emitting electrons and the underlying physical processes seem to be less important for this object in some epochs, since only seven out of the relatively rich spectra showed a curvature, while the majority of the 0.3–10 keV spectra fitted with a simple powerlaw well. The photon index varied on diverse timescales, and the source showed mainly a “harder-when-brighter” spectral evolution. In the hardness ratio–flux plane, 1ES 2344+514 showed both clockwise and counterclockwise loops, indicating a complex spectral evolution with the flux.