ItemArticle

Detection of time delay between UV and X-ray variability in Mrk 1044 using AstroSat observations

Title
Detection of time delay between UV and X-ray variability in Mrk 1044 using AstroSat observations
Creator
Reshma, M.; Stalin, C.S.; Mandal, Amit Kumar; Kayal, Abhijit; Gudennavar, S.B.; Joseph, Prajwel
Description
Active galactic nuclei are known to exhibit flux variations across the entire electromagnetic spectrum. Among these, correlations between UV/optical and X-ray flux variations serve as a key diagnostics for understanding the physical connection between the accretion disk and the corona. In this work, we present the results of analysis of ultraviolet (UV) and X-ray flux variations in the narrow line Seyfert 1 galaxy Mrk 1044. Simultaneous observations in the far-UV band (FUV: 1300 - 1800 and the X-ray band (0.5 - 7 keV) obtained during 31 August - 8 September 2018 with the Ultraviolet Imaging Telescope and the Soft X-ray Telescope onboard AstroSat were used for this study. Significant flux variability was detected in both FUV and X-ray bands. The fractional root mean square variability amplitude ( F var) was found to be 0.036 0.001 in the FUV band and 0.384 0.004 in the X-ray band. To explore potential time lag between the two bands, cross-correlation analysis was performed using both the interpolated cross-correlation function (ICCF) and just another vehicle for estimating lags in nuclei (JAVELIN) methods. Results from both approaches are consistent within 2 ? uncertainty, indicating that X-ray variations lead the FUV variations, with measured lags of 2.25 0.05 days (ICCF) and 2.35?0.01+0.02 days (JAVELIN). This is the first detection of a time delay between UV and X-ray variations in Mrk 1044. The observed UV lag supports the disk reprocessing scenario, wherein X-ray emission from the corona irradiates the accretion disk, driving the observed UV variability. 2026 Elsevier B.V.
Source
Journal of High Energy Astrophysics;Volume;51;Issue;;Article No.;100552;
Date
01-01-2026
Publisher
Elsevier B.V.
Subject
Active - galaxies; Galaxies; Galaxies - X-rays; Individual; Mrk 1044 - ultraviolet
Coverage
Reshma M., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Stalin C.S., Indian Institute of Astrophysics, Block II, Koramangala, Karnataka, Bangalore, 560034, India; Mandal A.K., Center for Theoretical Physics of the Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland; Kayal A., Indian Institute of Astrophysics, Block II, Koramangala, Karnataka, Bangalore, 560034, India; Gudennavar S.B., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Joseph P., Indian Institute of Astrophysics, Block II, Koramangala, Karnataka, Bangalore, 560034, India
Rights
Restricted Access; Hardcopy may be available in the library
Relation
ISSN: 22144048;
Format
online
Language
English
Type
Article

Citation

Reshma, M.; Stalin, C.S.; Mandal, Amit Kumar; Kayal, Abhijit; Gudennavar, S.B.; Joseph, Prajwel, “Detection of time delay between UV and X-ray variability in Mrk 1044 using AstroSat observations,” CHRIST (Deemed To Be University) Institutional Repository, accessed June 18, 2026, https://archives.christuniversity.in/items/show/22350.

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