SIMBAD references

2020ApJ...895..127B - Astrophys. J., 895, 127-127 (2020/June-1)

Swift monitoring of M51: a 38 day superorbital period for the pulsar ULX7 and a new transient ultraluminous X-ray source.

BRIGHTMAN M., EARNSHAW H., FURST F., HARRISON F.A., HEIDA M., ISRAEL G., PIKE S., STERN D. and WALTON D.J.

Abstract (from CDS):

We present the results from a monitoring campaign made with the Neil Gehrels Swift Observatory of the M51 galaxies, which contain several variable ultraluminous X-ray sources (ULXs). The ongoing campaign started in 2018 May, and we report here on ∼1.5 yr of observations. The campaign, which consists of 106 observations, has a typical cadence of 3-6 days, and has the goal of determining the long-term X-ray variability of the ULXs. Two of the most variable sources were ULX7 and ULX8, both of which are known to be powered by neutron stars that are exceeding their isotropic Eddington luminosities by factors of up to 100. This is further evidence that neutron-star-powered ULXs are the most variable. Our two main results are, first, that ULX7 exhibits a periodic flux modulation with a period of 38 days varying over a magnitude and a half in flux from peak to trough. Since the orbital period of the system is known to be 2 days, the modulation is superorbital, which is a near-ubiquitous property of ULX pulsars. Second, we identify a new transient ULX, M51 XT-1, the onset of which occurred during our campaign, reaching a peak luminosity of ∼1040 erg s–1, before gradually fading over the next ∼200 days until it slipped below the detection limit of our observations. Combined with the high-quality Swift/X-ray Telescope lightcurve of the transient, serendipitous observations made with Chandra and XMM-Newton provide insights into the onset and evolution of a likely super-Eddington event.

Abstract Copyright: © 2020. The American Astronomical Society. All rights reserved.

Journal keyword(s): X-ray point sources - X-ray transient sources - X-ray photometry - X-ray bright point - X-ray active galactic nuclei - Transient sources - Light curves - Galaxy nuclei - Active galactic nuclei

Nomenclature: [BEF2020] M51 XT-1 N=1.

Simbad objects: 29

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2023.01.30-11:59:39

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