A catalogue of intermediate-duration Type I X-ray bursts observed with the INTEGRAL satellite

K Alizai; J Chenevez; S Brandt; N Lund

doi:10.1093/mnras/staa831

A catalogue of intermediate-duration Type I X-ray bursts observed with the INTEGRAL satellite

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa831 ◽

2020 ◽

Vol 494 (2) ◽

pp. 2509-2522 ◽

Cited By ~ 1

Author(s):

K Alizai ◽

J Chenevez ◽

S Brandt ◽

N Lund

Keyword(s):

Accretion Rate ◽

Type I ◽

Emission Method ◽

X Ray ◽

Long Duration ◽

Photospheric Radius

ABSTRACT We present a catalogue of long-duration bursts observed with the Joint European X-ray Monitor and IBIS/ISGRI instruments onboard the INTEGRAL satellite. The 14 bursts have e-folding times ranging from 55 s to ≈17 min, and are therefore classified as intermediate-duration bursts, caused by the ignition of an unusually thick helium layer. Though seven events have already been reported in literature, we have systematically reanalysed the whole sample. We find three new photospheric radius expansion bursts, which are not reported in the literature, allowing us to provide a new estimate of the distances to these sources. We apply the enhanced persistent emission method (also known as the fa method) on sources with detectable persistent emission prior to a burst, in order to follow the evolution of the accretion rate during the burst. Although we do not get significantly better fits, the evolution of the fa factor shows an indicative behaviour, which we discuss.

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Cooling of accretion disc coronae by Type I X-ray bursts

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3137 ◽

2020 ◽

Vol 499 (3) ◽

pp. 4479-4489

Author(s):

J Speicher ◽

D R Ballantyne ◽

J Malzac

Keyword(s):

Accretion Rate ◽

Temperature Drop ◽

Accretion Disc ◽

Type I ◽

X Ray ◽

Geometrical Properties ◽

Fundamental Properties ◽

Cooling Effects ◽

The Impact ◽

Burst Emission

ABSTRACT Although accretion disc coronae appear to be common in many accreting systems, their fundamental properties remain insufficiently understood. Recent work suggests that Type I X-ray bursts from accreting neutron stars provide an opportunity to probe the characteristics of coronae. Several studies have observed hard X-ray shortages from the accretion disc during an X-ray burst implying strong coronal cooling by burst photons. Here, we use the plasma emission code eqpair to study the impact of X-ray bursts on coronae, and how the coronal and burst properties affect the coronal electron temperatures and emitted spectra. Assuming a constant accretion rate during the burst, our simulations show that soft photons can cool coronal electrons by a factor of ≳ 10 and cause a reduction of emission in the 30–50 keV band to $\lesssim 1{{\ \rm per\ cent}}$ of the pre-burst emission. This hard X-ray drop is intensified when the coronal optical depth and aspect ratio is increased. In contrast, depending on the properties of the burst and corona, the emission in the 8–24 keV band can either increase, by a factor of ≳ 20, or decrease, down to $\lesssim 1{{\ \rm per\ cent}}$ of the pre-burst emission. An increasing accretion rate during the X-ray burst reduces the coronal cooling effects and the electron temperature drop can be mitigated by $\gtrsim 60{{\ \rm per\ cent}}$. These results indicate that changes of the hard X-ray flux during an X-ray burst probe the geometrical properties of the corona.

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Discovery of thermonuclear Type-I X-ray bursts from the X-ray binary MAXI J1807+132

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3657 ◽

2020 ◽

Vol 501 (1) ◽

pp. 261-268

Author(s):

A C Albayati ◽

D Altamirano ◽

G K Jaisawal ◽

P Bult ◽

S Rapisarda ◽

...

Keyword(s):

Neutron Star ◽

Strong Evidence ◽

Compact Object ◽

Type I ◽

Time Resolved ◽

X Ray ◽

Upper Limit ◽

Low Mass ◽

Photospheric Radius ◽

Peak Luminosity

ABSTRACT MAXI J1807+132 is a low-mass X-ray binary (LMXB) first detected in outburst in 2017. Observations during the 2017 outburst did not allow for an unambiguous identification of the nature of the compact object. MAXI J1807+132 that was detected in outburst again in 2019 and was monitored regularly with Neutron Star Interior Composition Explorer(NICER). In this paper, we report on 5 days of observations during which we detected three thermonuclear (Type-I) X-ray bursts, identifying the system as a neutron star LMXB. Time-resolved spectroscopy of the three Type-I bursts revealed typical characteristics expected for these phenomena. All three Type-I bursts show slow rises and long decays, indicative of mixed H/He fuel. We find no strong evidence that any of the Type-I bursts reached the Eddington Luminosity; however, under the assumption that the brightest X-ray burst underwent photospheric radius expansion, we estimate a <12.4 kpc upper limit for the distance. We searched for burst oscillations during the Type-I bursts from MAXI J1807+132 and found none (<10 per cent amplitude upper limit at 95 per cent confidence level). Finally, we found that the brightest Type-I burst shows a ∼1.6 s pause during the rise. This pause is similar to one recently found with NICER in a bright Type-I burst from the accreting millisecond X-ray pulsar SAX J1808.4–3658. The fact that Type-I bursts from both sources can show this type of pause suggests that the origin of the pauses is independent of the composition of the burning fuel, the peak luminosity of the Type-I bursts, or whether the NS is an X-ray pulsar.

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Discovery of thermonuclear (Type I) X-ray bursts in the X-ray binary Swift J1858.6–0814 observed with NICER and NuSTAR

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2749 ◽

2020 ◽

Vol 499 (1) ◽

pp. 793-803

Author(s):

D J K Buisson ◽

D Altamirano ◽

P Bult ◽

G C Mancuso ◽

T Güver ◽

...

Keyword(s):

Compact Object ◽

Type I ◽

X Rays ◽

Helium Atmosphere ◽

X Ray ◽

Systematic Effects ◽

Photospheric Radius ◽

Rms Amplitude ◽

Peak Luminosity ◽

Stable Burning

ABSTRACT Swift J1858.6–0814 is a recently discovered X-ray binary notable for extremely strong variability (by factors of >100 in soft X-rays) in its discovery state. We present the detection of five thermonuclear (Type I) X-ray bursts from Swift J1858.6–0814, implying that the compact object in the system is a neutron star (NS). Some of the bursts show photospheric radius expansion, so their peak flux can be used to estimate the distance to the system. The peak luminosity, and hence distance, can depend on several system parameters; for the most likely values, a high inclination and a helium atmosphere, $D=12.8_{-0.6}^{+0.8}$ kpc, although systematic effects allow a conservative range of 9–18 kpc. Before one burst, we detect a QPO at 9.6 ± 0.5 mHz with a fractional rms amplitude of 2.2 ± 0.2 per cent (0.5–10 keV), likely due to marginally stable burning of helium; similar oscillations may be present before the other bursts but the light curves are not long enough to allow their detection. We also search for burst oscillations but do not detect any, with an upper limit in the best case of 15 per cent fractional amplitude (over 1–8 keV). Finally, we discuss the implications of the NS accretor and this distance on other inferences which have been made about the system. In particular, we find that Swift J1858.6–0814 was observed at super-Eddington luminosities at least during bright flares during the variable stage of its outburst.

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The type I X-ray bursts of 4U 1735–44

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312019862 ◽

2012 ◽

Vol 8 (S290) ◽

pp. 251-252

Author(s):

Y. J. Lei ◽

H. T. Zhang ◽

Y. Q. Dong ◽

H. L. Yuan

Keyword(s):

Accretion Rate ◽

Type I ◽

X Ray ◽

Mass Accretion Rate ◽

Peak Flux ◽

Low Mass

AbstractWith RXTE data ranging from 1997 August to 1998 May, we detected 8 type I X-ray bursts from the atoll source 4U 1735–44. The bursts are present at all the branches, and most occur at an inferred low mass accretion rate. We find no correlation between the peak flux of the bursts and the mass accretion rate. The results are different from that of 4U 1728-34, whose bursts' peak flux are anti-correlated with the mass accretion rate.

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A deficit of type I X-ray bursts from low-accretion-rate binaries: Data from the TTM/COMIS telescope onboard the Mir-Kvant observatory

Astronomy Letters ◽

10.1134/1.1424360 ◽

2001 ◽

Vol 27 (12) ◽

pp. 781-789 ◽

Cited By ~ 7

Author(s):

A. N. Emelyanov ◽

V. A. Aref’ev ◽

E. M. Churazov ◽

M. R. Gilfanov ◽

R. A. Sunyaev

Keyword(s):

Accretion Rate ◽

Type I ◽

X Ray

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The efficiency of nuclear burning during thermonuclear (Type I) bursts as a function of accretion rate

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2858 ◽

2020 ◽

Vol 499 (2) ◽

pp. 2148-2156

Author(s):

Y Cavecchi ◽

D K Galloway ◽

A J Goodwin ◽

Z Johnston ◽

A Heger

Keyword(s):

Neutron Star ◽

Binary Systems ◽

Accretion Rate ◽

Numerical Models ◽

Type I ◽

X Ray ◽

Accretion Rates ◽

Key Factor ◽

Nuclear Burning ◽

Stable Burning

ABSTRACT We measured the thermonuclear burning efficiency as a function of accretion rate for the Type I X-ray bursts of five low-mass X-ray binary systems. We chose sources with measured neutron star spins and a substantial population of bursts from a large observational sample. The general trend for the burst rate is qualitatively the same for all sources; the burst rate first increases with the accretion rate up to a maximum, above which the burst rate declines, despite the increasing accretion rate. At higher accretion rates, when the burst rate decreases, the α-value (the ratio of accretion energy and burst energy) increases by up to a factor of 10 above that in the rising burst rate regime. These observations are contrary to the predictions of 1D numerical models, but can be explained as the consequence of a zone of stable burning on the neutron star surface, which expands with increasing accretion rate. The stable burning also ‘pollutes’ the unstable burning layer with ashes, contributing to the change in burst properties measured in the falling burst rate regime. We find that the mass accretion rate at which the burst rate begins to decrease is anticorrelated with the spin of the neutron star. We conclude that the neutron star spin is a key factor, moderating the nuclear burning stability, via the local accretion rate and fuel composition over the star.

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Thermonuclear Burst Observations for Model Comparisons: A Reference Sample

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.12 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 12

Author(s):

Duncan K. Galloway ◽

Adelle J. Goodwin ◽

Laurens Keek

Keyword(s):

Accretion Rate ◽

Numerical Models ◽

Reference Sample ◽

Recurrence Time ◽

Test Cases ◽

Type I ◽

Time Resolved ◽

X Ray ◽

Peak Flux ◽

Flux Level

AbstractWe present observations of thermonuclear (type-I) X-ray bursts, selected for comparison with numerical models. We provide examples of four distinct cases of ignition: He-ignition in mixed H/He fuel (case 1); He-ignition in pure He fuel, following exhaustion of accreted H by steady burning (case 2); ignition in (almost) pure He accumulated from an evolved donor in an ultracompact system; and a superburst, thought to arise from ignition of carbon fuel produced as a by-product of H/He bursts. For regular bursts, we measured the recurrence time and calculated averaged burst profiles from RXTE observations. We also estimated the recurrence time for pairs of bursts, including those observed during a transient outburst, modelled using a numerical ignition code. For each example we list the burst properties including recurrence time, fluence, peak flux, the persistent flux level (and inferred accretion rate), and the ratio of persistent flux to fluence. In the accompanying material, we provide a bolometric lightcurve for each burst, determined from time-resolved spectral analysis. Along with the inferred or adopted parameters for each burst system, including distance, surface gravity, and redshift, these data are suggested as suitable test cases for ignition models.

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EVIDENCE FOR ACCRETION RATE CHANGE DURING TYPE I X-RAY BURSTS

The Astrophysical Journal ◽

10.1088/0004-637x/772/2/94 ◽

2013 ◽

Vol 772 (2) ◽

pp. 94 ◽

Cited By ~ 68

Author(s):

Hauke Worpel ◽

Duncan K. Galloway ◽

Daniel J. Price

Keyword(s):

Accretion Rate ◽

Rate Change ◽

Type I ◽

X Ray

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Gaia EDR3 parallaxes of type I X-ray bursters and their implications on the models of type I X-ray bursts: A generic approach to the Gaia parallax zero point and its uncertainty

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2021.37 ◽

2021 ◽

Vol 38 ◽

Author(s):

Hao Ding ◽

Adam T. Deller ◽

James C. A. Miller-Jones

Keyword(s):

Zero Point ◽

Light Curves ◽

Symmetric Model ◽

Type I ◽

Spherically Symmetric ◽

X Ray ◽

Test Models ◽

Model Independent ◽

Spherically Symmetric Model ◽

Photospheric Radius

Abstract Light curves of photospheric radius expansion (PRE) bursts, a subset of type I X-ray bursts, have been used as standard candles to estimate the ‘nominal PRE distances’ for 63% of PRE bursters (bursters), assuming PRE burst emission is spherically symmetric. Model-independent geometric parallaxes of bursters provide a valuable chance to test models of PRE bursts (PRE models) and can be provided in some cases by Gaia astrometry of the donor stars in bursters. We searched for counterparts to 115 known bursters in the Gaia Early Data Release 3 and confirmed 4 bursters with Gaia counterparts that have detected ( $\gt\!3\,\sigma$ , prior to zero-point correction) parallaxes. We describe a generic approach to the Gaia parallax zero point as well as its uncertainty using an ensemble of Gaia quasars individually determined for each target. Assuming the spherically symmetric PRE model is correct, we refined the resultant nominal PRE distances of three bursters (i.e. Cen $\textrm{X}-4$ , Cyg $\textrm{X}-2$ , and $4\textrm{U}\,0919-54$ ) and put constraints on their compositions of the nuclear fuel powering the bursts. Finally, we describe a method for testing the correctness of the spherically symmetric PRE model using parallax measurements and provide preliminary results.

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