scholarly journals The study of multipeaked type-I X-ray bursts in the neutron star low-mass X-ray binary 4U 1636 − 536 with RXTE

2020 ◽  
Vol 501 (1) ◽  
pp. 168-178
Author(s):  
Chen Li ◽  
Guobao Zhang ◽  
Mariano Méndez ◽  
Jiancheng Wang ◽  
Ming Lyu
Keyword(s):  
Neutron Star ◽  
Flux Ratio ◽  
Light Curves ◽  
Type I ◽  
X Ray ◽  
Soft State ◽  
Peak Flux ◽  
Low Mass ◽  
Two Peaks ◽  
Second Peak

ABSTRACT We have found and analysed 16 multipeaked type-I bursts from the neutron-star low-mass X-ray binary 4U 1636 − 53 with the Rossi X-ray Timing Explorer (RXTE). One of the bursts is a rare quadruple-peaked burst that was not previously reported. All 16 bursts show a multipeaked structure not only in the X-ray light curves but also in the bolometric light curves. Most of the multipeaked bursts appear in observations during the transition from the hard to the soft state in the colour–colour diagram. We find an anticorrelation between the second peak flux and the separation time between two peaks. We also find that in the double-peaked bursts the peak-flux ratio and the temperature of the thermal component in the pre-burst spectra are correlated. This indicates that the double-peaked structure in the light curve of the bursts may be affected by enhanced accretion rate in the disc, or increased temperature of the neutron star.

scholarly journals Rapidly Evolving Light Curves of Low Mass X-Ray Binaries

2004 ◽  
Vol 194 ◽  
pp. 211-211
Author(s):  
P. Muhli ◽  
P. J. Hakala ◽  
L. Hjalmarsdotter ◽  
D. C. Hannikainen ◽  
J. Schultz
Keyword(s):  
Neutron Star ◽  
Light Curve ◽  
Light Curves ◽  
Type I ◽  
X Ray ◽  
Short Period ◽  
First Results ◽  
Low Mass ◽  
Photometric Monitoring ◽  
X Ray Binaries

A few Galactic Low Mass X-Ray Binaries (LMXBs) have shown drastically evolving X-ray and/or optical orbital light curves. In two short-period LMXBs, MS 1603+2600 (= UW CrB, Porb = 111 min) and 4U 1916-053 (see e.g. Homer et al. 2001), the variations in the light curve morphology seem to be repeating in a periodic manner. We present first results of a photometric monitoring campaign of MS 1603+2600, showing evidence of a 5-day superorbital period in this yet unclassified source. The observations also unraveled optical flares, reminiscent of type I bursts, suggesting a neutron star primary.

scholarly journals Optical Photometry of LMXBs: UW CrB (=MS 1603+260) and V1408 Aql (=4U 1957+115)

2015 ◽  
Vol 2 (1) ◽  
pp. 50-54
Author(s):  
P. A. Mason ◽  
E. L. Robinson ◽  
S. Gomez ◽  
J. V. Segura
Keyword(s):  
Black Hole ◽  
Orbital Period ◽  
Light Curves ◽  
Optical Data ◽  
Published Data ◽  
Type I ◽  
Optical Photometry ◽  
Mean Intensity ◽  
X Ray ◽  
Low Mass

We present new optical observations of V1408 Aql (= 4U 1957+115), the only low mass X-ray binary, black hole candidate known to be in a persistently soft state. We combine new broadband optical photometry with previously published data and derive a precise orbital ephemeris. The optical light curves display sinusoidal variations modulated on the orbital period as well as large night to night changes in mean intensity. The amplitude of the variations increases with mean intensity while maintaining sinusoidal shape. Considering the set of constraints placed by the X-ray and optical data we argue that V1408 Aql may harbor a very low mass black hole. Optical light curves of UW CrB display partial eclipses of the accretion disk by the donor star that vary both in depth and orbital phase. The new eclipses of UW CrB in conjunction with published eclipse timings are well fitted with a linear ephemeris. We derive an upper limit to the rate of change of the orbital period. By including the newly observed type I bursts with published bursts in our analysis, we find that optical bursts are not observed between orbital phases 0.93 and 0.07, i.e. they are not observable during partial eclipses of the disk.

scholarly journals Hard-tail emission in the soft state of low-mass X-ray binaries and their relation to the neutron star magnetic field

2016 ◽  
Vol 68 (4) ◽  
pp. 50
Author(s):  
Kazumi Asai ◽  
Tatehiro Mihara ◽  
Masaru Mastuoka ◽  
Mutsumi Sugizaki
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
X Ray ◽  
Soft State ◽  
Low Mass ◽  
X Ray Binaries

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

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.

scholarly journals The connection between the UV/optical and X-ray emission in the neutron star low-mass X-ray binary Aql X-1

2020 ◽  
Vol 493 (1) ◽  
pp. 940-951
Author(s):  
E López-Navas ◽  
N Degenaar ◽  
A S Parikh ◽  
J V Hernández Santisteban ◽  
J van den Eijnden
Keyword(s):  
Neutron Star ◽  
Optical Emission ◽  
Optical Observations ◽  
Electromagnetic Spectrum ◽  
Strongly Correlated ◽  
X Ray ◽  
Soft State ◽  
Low Mass ◽  
X Ray Binaries ◽  
Hysteresis Behaviour

ABSTRACT Accreting neutron stars and black holes in low-mass X-ray binaries (LMXBs) radiate across the electromagnetic spectrum. Linking the emission produced at different wavelengths can provide valuable information about the accretion process and any associated outflows. In this work, we study simultaneous X-ray and ultraviolet (UV)/optical observations of the neutron star LMXB Aql X-1, obtained with the Neil Gehrels Swift Observatory during its 2013, 2014, and 2016 accretion outbursts. We find that the UV/optical and X-ray emission are strongly correlated during all three outbursts. For the 2013 and 2014 episodes, which had the best Swift sampling, we find that the correlation between the UV/optical and X-ray fluxes is significantly steeper during the decay (soft state) of the outburst than during the rise (hard-to-soft state). We observe a UV/optical hysteresis behaviour that is likely linked to the commonly known X-ray spectral hysteresis pattern. For the decays of the three outbursts, we obtain a correlation index that cannot be directly explained by any single model. We suspect that this is a result of multiple emission processes contributing to the UV/optical emission, but we discuss alternative explanations. Based on these correlations, we discuss which mechanisms are likely dominating the UV/optical emission of Aql X-1.

scholarly journals The newly discovered Be/X-ray binary Swift J004516.6–734703 in the SMC: witnessing the emergence of a circumstellar disc

2020 ◽  
Vol 499 (1) ◽  
pp. L41-L46
Author(s):  
J A Kennea ◽  
M J Coe ◽  
P A Evans ◽  
I M Monageng ◽  
L J Townsend ◽  
...  
Keyword(s):  
Neutron Star ◽  
Binary System ◽  
Light Curves ◽  
Type I ◽  
Pulsation Period ◽  
X Ray ◽  
Tidal Interaction ◽  
Long Period ◽  
Periodicity Analysis ◽  
Ir Light

ABSTRACT We report on the discovery of Swift J004516.6–734703, a Be/X-ray binary system by the Swift SMC Survey, S-CUBED. Swift J004516.6–734703, or SXP 146.6, was found to be exhibiting a bright (∼1037 erg s−1) X-ray outburst on 2020 June 18. The historical UV and IR light-curves from OGLE and Swift/UVOT showed that after a long period of steady brightness, it experienced a significant brightening beginning around 2019 March. This IR/UV rise is likely the signature of the formation of a circumstellar disc, confirmed by the presence of strong an H α line in SALT spectroscopy, that was not previously present. Periodicity analysis of the OGLE data reveals a plausible 426 d binary period, and in X-ray a pulsation period of 146.6 s is detected. The onset of X-ray emission from Swift J004516.6–734703 is likely the signature of a Type-I outburst from the first periastron passage of the neutron star companion through the newly formed circumstellar disc. We note that the formation of the circumstellar disc began at the predicted time of the previous periastron passage, suggesting its formation was spurred by tidal interaction with the neutron star.

scholarly journals The type I X-ray bursts of 4U 1735–44

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.

scholarly journals The Galactic center X-ray transients AX J1745.6–2901 and GRS 1741–2853

2013 ◽  
Vol 9 (S303) ◽  
pp. 315-317
Author(s):  
N. Degenaar ◽  
R. Wijnands ◽  
M. T. Reynolds ◽  
J. M. Miller ◽  
J. Kennea ◽  
...  
Keyword(s):  
Neutron Star ◽  
Galactic Center ◽  
Light Curves ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractAX J1745.6–2901 and GRS 1741–2853 are two transient neutron star low-mass X-ray binaries that are located within ≃ 10′ from the Galactic center. Multi-year monitoring observations with the Swift/XRT has exposed several accretion outbursts from these objects. We report on their updated X-ray light curves and renewed activity that occurred in 2010–2013.

scholarly journals Binary X-Ray Stars and Supernovae of Type I

1976 ◽  
Vol 73 ◽  
pp. 19-25
Author(s):  
H. Gursky
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
Binary Systems ◽  
Close Binary ◽  
Type I ◽  
Mass Limit ◽  
X Ray ◽  
Close Binary Systems ◽  
Low Mass

Most of the strong galactic X-ray sources must be low mass, close binary systems, such as Her X-1 and Sco X-1. Two evolutionary scenarios are discussed, both involving type I supernovae that occur when mass-accreting white dwarfs are driven over their mass limit. In one, accepting the correctness of the idea that a neutron star or black hole is the seat of the X-ray emission, the SN occurs before the system is an X-ray source. Another possibility is that the white dwarf is the X-ray source, just prior to its collapse and the ensuing SN.

scholarly journals A peculiar thermonuclear X-ray burst from the transiently accreting neutron star SAX J1810.8–2609

2012 ◽  
Vol 8 (S291) ◽  
pp. 141-144
Author(s):  
N. Degenaar ◽  
R. Wijnands
Keyword(s):  
Neutron Star ◽  
Early Stage ◽  
Type I ◽  
X Ray ◽  
Radiated Energy ◽  
Low Mass ◽  
Peak Luminosity

AbstractWe report on a thermonuclear (type-I) X-ray burst that was detected from the neutron star low-mass X-ray binary SAX J1810.8–2609 in 2007 with Swift. This event was longer (≃20 min) and more energetic (a radiated energy of Eb≃6.5×1039 erg) than other X-ray bursts observed from this source. A possible explanation for the peculiar properties is that the X-ray burst occurred during the early stage of the outburst when the neutron star was relatively cold, which allows for the accumulation of a thicker layer of fuel. We also report on a new accretion outburst of SAX J1810.8–2609 that was observed with MAXI and Swift in 2012. The outburst had a duration of ≃17 days and reached a 2–10 keV peak luminosity of ≃ 3 × 1037 (D/5.7 kpc)2 erg s−1. This is a factor >10 more luminous than the two previous outbursts observed from the source, and classifies it as a bright rather than a faint X-ray transient.

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