All at Once: Transient Pulsations, Spin-down, and a Glitch from the Pulsating Ultraluminous X-Ray Source M82 X-2

Bachetti, Matteo; Maccarone, Thomas J.; Brightman, Murray; Brumback, McKinley C.; Fürst, Felix; Harrison, Fiona A.; Heida, Marianne; Israel, G. L.; Middleton, Matthew; Tomsick, John A.; Webb, N.; Walton, D. J.

doi:10.3847/1538-4357/ab6d00

Cited by 47 publications

(54 citation statements)

References 106 publications

(80 reference statements)

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“…If the spin period of a NS is smaller than the light travel time (colored regions below the solid lines), pulsations from a ULX are undetectable for a given geometry of accretion flow. Horizontal dotted lines represent the observed pulsation periods of four ULX pulsars: NGC 300 ULX1 (Carpano et al 2018), M82 X-2 (Bachetti et al 2014(Bachetti et al , 2020, NGC 5907 ULX1 (Israel et al 2017a), NGC 7793 P13 (Fürst et al 2016;Israel et al 2017b).…”

Section: Light Travel Timementioning

confidence: 99%

Pulsating ULXs: large pulsed fraction excludes strong beaming

Mushtukov

Zwart

Tsygankov

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The recent discovery of pulsating ultraluminous X-ray sources (ULXs) shows that the apparent luminosity of accreting neutron stars can exceed the Eddington luminosity by a factor of 100s. The relation between the actual and apparent luminosity is a key ingredient in theoretical models of ULXs, but it is still under debate. A typical feature of the discovered pulsating ULXs is a large pulsed fraction (PF). Using Monte Carlo simulations, we consider a simple geometry of accretion flow and test the possibility of simultaneous presence of a large luminosity amplification due the geometrical beaming and a high PF. We argue that these factors largely exclude each other and only a negligible fraction of strongly beamed ULX pulsars can show PF above 10 per cent. Discrepancy between this conclusion and current observations indicates that pulsating ULXs are not strongly beamed and their apparent luminosity is close to the actual one.

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Section: Light Travel Timementioning

confidence: 99%

Pulsating ULXs: large pulsed fraction excludes strong beaming

Mushtukov

Zwart

Tsygankov

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Although we do not have any significant detection of X-ray pulsations from ULX3, the current limits are only mildly constraining, and the pulsations are seen to be transient in a number of the known ULX pulsars (e.g. Israel et al 2017a;Sathyaprakash et al 2019;Bachetti et al 2020). Furthermore, as discussed earlier, the lack of spectral complexity similar to that seen in other known ULX pulsars could easily be purely due to a combination of relatively high absorption and low S/N at high energies.…”

Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 55%

A new transient ultraluminous X-ray source in NGC 7090

Walton

Heida

Bachetti

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report on the discovery of a new, transient ultraluminous X-ray source (ULX) in the galaxy NGC 7090. This new ULX, which we refer to as NGC 7090 ULX3, was discovered via monitoring with Swift during 2019–20, and to date has exhibited a peak luminosity of LX ∼ 6 × 1039 erg s−1. Archival searches show that, prior to its recent transition into the ULX regime, ULX3 appeared to exhibit a fairly stable luminosity of LX ∼ 1038 erg s−1. Such strong long-timescale variability may be reminiscent of the small population of known ULX pulsars, although deep follow-up observations with XMM-Newton and NuSTAR do not reveal any robust X-ray pulsation signals. Pulsations similar to those seen from known ULX pulsars cannot be completely excluded, however, as the limit on the pulsed fraction of any signal that remains undetected in these data is ≲20%. The broadband spectrum from these observations is well modelled with a simple thin disc model, consistent with sub-Eddington accretion, which may instead imply a moderately large black hole accretor (MBH ∼ 40 M⊙). Similarly, though, more complex models consistent with the super-Eddington spectra seen in other ULXs (and the known ULX pulsars) cannot be excluded given the limited signal-to-noise of the available broadband data. The nature of the accretor powering this new ULX therefore remains uncertain.

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“…Ghosh & Lamb 1979;Wang 1995), given a corotation radius co and a magnetospheric radius co one expects the frequency derivative to be roughly related to luminosity (see, e.g. Bachetti et al 2020)…”

Section: Discussionmentioning

confidence: 99%

A new candidate pulsating ULX in NGC 7793

Quintin

Webb

Gúrpide

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We report here the discovery of NGC 7793 ULX-4, a new transient ultraluminous X-ray source (ULX) in NGC 7793, a spiral galaxy already well known for harbouring several ULXs. This new source underwent an outburst in 2012, when it was detected by XMM-Newton and the Swift X-ray telescope. The outburst reached a peak luminosity of 3.4 × 1039 erg s−1 and lasted for about 8 months, after which the source went below a luminosity of 1037 erg s−1; previous Chandra observations constrain the low-state luminosity below ∼ 2× 1036 erg s−1, implying a variability of at least a factor 1000. We propose four possible optical counterparts, found in archival HST observations of the galaxy. A pulsation in the XMM-Newton signal was found at 2.52 Hz, with a significance of ∼3.4 σ, and an associated spin-up of $\dot{f} = 3.5\times 10^{-8}$ Hz s−1. NGC 7793 is therefore the first galaxy to host more than one pulsating ULX.

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All at Once: Transient Pulsations, Spin-down, and a Glitch from the Pulsating Ultraluminous X-Ray Source M82 X-2

Cited by 47 publications

References 106 publications

Pulsating ULXs: large pulsed fraction excludes strong beaming

Pulsating ULXs: large pulsed fraction excludes strong beaming

A new transient ultraluminous X-ray source in NGC 7090

A new candidate pulsating ULX in NGC 7793

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