Dead discs, unstable discs and the stars they surround

D’Angelo, Caroline

doi:10.1051/epjconf/20136401003

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…It is generally thought that this material is then expelled from the inner part of these systems through what is called the 'propeller effect' (Illarionov & Sunyaev 1975;Romanova et al 2004;D'Angelo & Spruit 2010). If the propeller effect is not very strong, the matter might also accumulate outside of the magnetosphere in what is called a 'trapped' or 'dead disk' (see, e.g., Syunyaev & Shakura 1977;D'Angelo & Spruit 2012;Patruno & D'Angelo 2013;D'Angelo 2014).…”

Section: Introductionmentioning

confidence: 99%

Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27

Escorial

Wijnands

Ootes

et al. 2019

A&A

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The Be/X-ray transient GRO J1750-27 exhibited a type-II (giant) outburst in 2015. After the source transited to quiescence, we triggered our multi-year Chandra monitoring programme to study its quiescent behaviour. The programme was designed to follow the cooling of a potentially heated neutron-star crust due to accretion of matter during the preceding outburst, similar to what we potentially have observed before in two other Be/X-ray transients, namely 4U 0115+63 and V 0332+53. However, unlike for these other two systems, we do not find any strong evidence that the neutron-star crust in GRO J1750-27 was indeed heated during the accretion phase. We detected the source at a rather low X-ray luminosity (∼10 33 erg s −1 ) during only three of our five observations. When the source was not detected it had very low-luminosity upper limits (< 10 32 erg s −1 ; depending on assumed spectral model). We interpret these detections and the variability observed as emission likely due to very low-level accretion onto the neutron star. We also discuss why the neutron-star crust in GRO J1750-27 might not have been heated while the ones in 4U 0115+63 and V 0332+53 possibly were.

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Section: Introductionmentioning

confidence: 99%

Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27

Escorial

Wijnands

Ootes

et al. 2019

A&A

View full text Add to dashboard Cite

show abstract

“…In some cases, this mechanism might not be effective enough to expel matter, and material is still stored in a disk (in what is often called a 'trapped' or 'dead' disk) that remains coupled to the NS magnetic field even after the active accretion period has halted (e.g. Syunyaev & Shakura 1977;D'Angelo & Spruit 2012;Patruno & D'Angelo 2013;D'Angelo 2014).…”

Section: The Low-luminosity Behaviour Of Bexbsmentioning

confidence: 99%

Recurrent low-level luminosity behaviour after a giant outburst in the Be/X-ray transient 4U 0115+63

Escorial,

Wijnands,

Eijnden

et al. 2019

Preprint

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In 2017, the Be/X-ray transient 4U 0115+63 exhibited a new type-II outburst that was two times fainter than its 2015 giant outburst (in the Swift/BAT count rates). Despite this difference between the two bright events, the source displayed similar X-ray behaviour after these periods. Once the outbursts ceased, the source did not transit towards quiescence directly, but was detected about a factor of 10 above its known quiescent level. It eventually decayed back to quiescence over time scales of months. In this paper we present the results of our Swift monitoring campaign, and an XMM-Newton observation of 4U 0115+63 during the decay of the 2017 type-II outburst, and its subsequent low-luminosity behaviour. We discuss the possible origin of the decaying source emission at this lowlevel luminosity, which has now been shown as a recurrent phenomenon, in the framework of the two proposed scenarios to explain this faint state: cooling from an accretion-heated neutron-star crust or continuous low-level accretion. In addition, we compare the outcome of our study with the results we obtained from the 2015/2016 monitoring campaign on this source.

show abstract

“…In some cases, this mechanism might not be effective enough to expel matter, and material is still stored in a disc (in what is often called a "trapped" or "dead" disc) that remains coupled to the NS magnetic field even after the active accretion period has halted (e.g. Syunyaev & Shakura 1977;D'Angelo & Spruit 2012;Patruno & D'Angelo 2013;D'Angelo 2014).…”

Section: Introductionmentioning

confidence: 99%

Recurrent low-level luminosity behaviour after a giant outburst in the Be/X-ray transient 4U 0115+63

Escorial

Wijnands

Eijnden

et al. 2020

A&A

View full text Add to dashboard Cite

In 2017, the Be/X-ray transient 4U 0115+63 exhibited a new type II outburst that was two times fainter than its 2015 giant outburst (in the Swift/BAT count rates). Despite this difference between the two bright events, the source displayed similar X-ray behaviour after these periods. Once the outbursts ceased, the source did not transit towards quiescence directly, but was detected about a factor of 10 above its known quiescent level. It eventually decayed back to quiescence over timescales of months. In this paper, we present the results of our Swift monitoring campaign, and an XMM-Newton observation of 4U 0115+63 during the decay of the 2017 type II outburst and its subsequent low-luminosity behaviour. We discuss the possible origin of the decaying source emission at this low-level luminosity, which has now been shown as a recurrent phenomenon, in the framework of the two proposed scenarios to explain this faint state: cooling from an accretion-heated neutron star crust or continuous low-level accretion. In addition, we compare the outcome of our study with the results we obtained from the 2015/2016 monitoring campaign on this source.

show abstract

Dead discs, unstable discs and the stars they surround

Cited by 4 publications

References 25 publications

Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27

Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27

Recurrent low-level luminosity behaviour after a giant outburst in the Be/X-ray transient 4U 0115+63

Recurrent low-level luminosity behaviour after a giant outburst in the Be/X-ray transient 4U 0115+63

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