AR_final file_2018-19

mality of the flux distribution. In case of skewness analysis, they showed that the sample size (number of flux points in the distribution) should be greater than 200 for the skewness significance of 3 or more. They also showed that AD test requires lesser num- ber of points compared to skewness test for the re- jection of normality of flux distribution. They also demonstrated that the slope of error distribution in which errors are weighted with the flux values was significant only for large percentage of error, and the binning of log-normal flux distribution did not change the log-normal behaviour of the distri- bution. On applying these results to eight year monthly binned γ -ray light curve of bright Fermi blazar, viz. 3FGL J0730.2-1141, they found that the AD test results were more significant to confirm the log-normality of distribution than the skewness test. Moreover, they studied the power-law noise generated with Timmer and Koenig algorithm for three slopes β = 0.0, 0.5, 1.0, and they found that AD test rejected the normality of power-law noise for large sample size of blazars with non-zero spec- tral slope. However, power law noise generated with Timmer and Koenig algorithm being essen- tially normal distribution, advocates for modifica- tion in the critical values of AD test. They gener- ated new AD critical values for the power-law noise with slopes 0.5 and 1.0 such that new critical values did not reject the normality of the generated power law noise. Spectral-timing analysis of Seyfert 1 galaxy Mrk 1044 Gulab C. Dewangan , Labani Mallick , Ajit K. Kembhavi , Ranjeev Misra , and collaborators have performed a detailed spectral-timing analy- sis of a long (130 ks) XMM-Newton observation and quasi-simultaneous NuSTAR and Swift obser- vations of the highly accreting narrow-line Seyfert 1 galaxy Mrk 1044. The broad-band (0.3-50 keV) spectrum reveals the presence of a strong soft X- ray excess emission below 1.5 keV, iron K emis- sion complex at 6-7 keV and a ‘Compton hump’ at 15-30 keV. They find that the relativistic re- flection from a high-density accretion disc with a broken power-law emissivity profile can simultane- ously explain the soft X-ray excess, highly ionized broad iron line and the Compton hump. At low fre- quencies, the power-law continuum-dominated 1.5- 5 keV band lags behind the reflection-dominated 0.3-1 keV band, which is explained with a combi- nation of propagation fluctuation and Comptoniza- tion processes, while at higher frequencies, a soft lag is detected which is interpreted as a signa- ture of X-ray reverberation from the accretion disc. The fractional root-mean-squared variability of the source decreases with energy, and is well described by two variable components: a less variable rela- tivistic disc reflection and a more variable direct coronal emission. The combined spectral-timing analyses has suggested that the observed broad- band X-ray variability of Mrk 1044 is mainly driven by variations in the location or geometry of the op- tically thin, hot corona. Broad-band spectral study of Seyfert 1 galaxy 1H 0323+342 Ritesh Ghosh, Gulab C. Dewangan , Labani Mallick and Biplab Raychaudhuri have performed a detailed broad-band spectral study of the radio- loud narrow-line Seyfert 1 galaxy 1H 0323+342, based on multi-epoch observations performed with Nuclear Spectroscopic Telescope Array on March 15, 2014 and two simultaneous observations per- formed with Suzaku and Swift on July 26, 2009 and March 1, 2013. They found the presence of a strong soft X-ray excess emission, a broad but weak Fe line and hard X-ray excess emission. They used the blurred reflection and the intrinsic disc Comptonization (optxagnf), two physically moti- vated models, to describe the broad-band spectra and to disentangle the disc/corona and jet emis- sion. The relxill model is mainly constrained by the strong soft X-ray excess although the model failed to predict this excess when fitted above 3 keV and extrapolated to lower energies. The joint spectral analysis of the three data sets above 3 keV with this model resulted in a high black hole spin and moderate reflection. The optxagnf model fit- ted to the two simultaneous data sets resulted in an excess emission in the ultraviolet (UV) band. The simultaneous UV-to-hard X-ray spectra are best de- ( 79 )