1. The restless population of bright X-ray sources of NCG 3621
- Author
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Sacchi, A., Imbrogno, M., Motta, S. E., Esposito, P., Israel, G. L., Vago, N. O. Pinciroli, De Luca, A., Marelli, M., Pintore, F., Castillo, G. A. Rodríguez, Salvaterra, R., and Tiengo, A.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report on the multi-year evolution of the population of X-ray sources in the nuclear region of NGC 3621 based on Chandra, XMM-Newton and Swift observations. Among these, two sources, X1 and X5, after their first detection in 2008, seem to have faded below the detectability threshold, a most interesting fact as X1 is associated with the AGN of the galaxy. Two other sources, X3 and X6 are presented for the first time, the former showing a peculiar short-term variability in the latest available dataset, suggesting an egress from eclipse, hence belonging to the handful of known eclipsing ultra-luminous X-ray sources. One source, X4, previously known for its "heart-beat", i.e. a characteristic modulation in its signal with a period of $\approx1$ h, shows a steady behaviour in the latest observation. Finally, the brightest X-ray source in NGC 3621, here labelled X2, shows steady levels of flux across all the available datasets but a change in its spectral shape, reminiscent of the behaviours of Galactic disk-fed X-ray binaries., Comment: 11 pages, 10 figures, 3 tables, 2 appendices available online. Accepted for publication on A&A
- Published
- 2024
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