The restless population of bright X-ray sources of NCG 3621

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 $\approx 1$ 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.

11 pages, 10 figures, 3 tables, 2 appendices available online. Accepted for publication on A&A

References in corpus (14)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• XMM-Newton observations of the brightest Ultraluminous X-ray sources
• Ultraluminous X-ray sources
• Pulse profiles of millisecond pulsars and their Fourier amplitudes
• Ultraluminous X-Ray Sources
• Dynamical Constraints on The Masses of the Nuclear Star Cluster and Black Hole in the Late-Type Spiral Galaxy NGC 3621
• Long-term X-ray spectral evolution of Ultraluminous X-ray sources: implications on the accretion flow geometry and the nature of the accretor
• A Chandra view of NGC 3621: a bulgeless galaxy hosting an AGN in its early phase?
• Two eclipsing ultraluminous X-ray sources in M 51
• The Chandra ACIS Timing Survey Project: glimpsing a sample of faint X-ray pulsators
• The slow heartbeats of an ultra-luminous X-ray source in NGC 3621
• Testing the relativistic Doppler boost hypothesis for supermassive binary black holes candidates via broad emission line profiles
• Swift observations of the ultraluminous X-ray source XMMU J004243.6+412519 in M31
• Orbital and Radiative Properties of Wandering Intermediate-Mass Black Holes in the ASTRID Simulation

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