AR_final file_2018-19

Figure 15: Optical and X-ray images of the central 25 ′′ × 25 ′′ of A2626. (a) HST F555W image, (b) SDSS r– band image, (c), (d) Chandra images using ObsId 3192, (e) and (f) Chandra images using ObsId 16136. Each of the Chandra images is divided into two different energy bins, the soft (0.5–1 keV) and the hard (2–8 keV), and are smoothed using a 2-pixel-wide Gaussian. previous detection of the east cavity at 13 kpc and reports the detection of a new cavity at 39 kpc to the west of the X–ray peak. The average mechanical power injected by the active galactic nucleus outburst is found to be ∼ 30 times more than that required to compensate the cooling luminosity. The edges in the surface brightness are spatially associated with arcs in the temperature and metallicity maps, and are attributed due to the merging cold fronts. A systematic study of the nuclear twin sources exhibited dramatic changes over the span of 10 years (See Figure 15). The NE source that emitted mostly in the soft X–ray band in the past had disappeared in the recent observations. Instead, an excess emission has been seen at 2.2 arcsec to its west that required an unrealistic line–of–sight velocity of 675 c if it is due to its relative motion. The count rate and spectral analysis exhibited a change in the state of the SW source from a soft to a hard state due to the change in the mass accretion rate. UV and X-ray variability in Seyfert 1 galaxies The emission from active galactic nuclei (AGN) has been found to be variable at all observed wavelengths. The variability time-scales in dif- ferent bands can range from years to months or even hours. Previous studies have shown that the variations in the optical/UV continuum in Seyfert galaxies are well correlated with the variations in the X-rays. But the exact origin of optical/UV variability in AGN is not yet clearly understood. In an ongoing work, Savithri H. Ezhikode, Gulab C. Dewangan, Ranjeev Misra , Krish- napriya K. V. and Geethika B. R. study the UV and X-ray variability of two Seyfert type 1 AGN in the nearby universe, Mrk 110 (redshift = 0.035) and Mrk 926 (redshift = 0.047). Both the sources have been observed in UV and X-ray wavelengths for years by different missions. They analyse the multi-wavelength data from AstroSat, Swift, XMM-Newton, GALEX, Suzaku and NuSTAR observations to study the short and long term variability of the sources in UV and X-ray bands. The study allowed then to investigate the origin of UV variability in these sources, and how it is connected to the X-ray variability. There are two possibilities: (i) either the observed UV variability may be arising from the accretion rate fluctuations, or (ii) it may be due to the X-ray reprocessing mechanism. AstroSat observations of the HBL blazar 1ES 1959+650 Blazars constitute a special subclass of AGN with a relativistic jet aligned close to the line of sight of the observer. They emit non-thermal radiation extending from the radio to the very high energy gamma-rays (E > 100 GeV), and exhibit strong flux variability in all observed bands. Savithri H. Ezhikode, Ranjeev Misra, Zahir Shah , and Rajalakshmi T. R. have studied the nearby (redshift = 0.047) TeV-detected high-frequency BL-Lac (HBL) object 1ES 1959+650 which is very bright in the X-ray (0.3-10 keV) band. The source ( 82 )