High-Frequency Variability in Neutron-Star Low-Mass X-ray Binaries

Méndez, Mariano; Belloni, T.

doi:10.1007/978-3-662-62110-3_6

Cited by 13 publications

(3 citation statements)

References 176 publications

(285 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, we attempted to infer the nature of the compact object from the timing and spectral properties. We searched for the presence of high-frequency kHz QPOs, seen in several NSs (Di Salvo et al 2001;van Doesburgh & van der Klis 2017;Bult et al 2018;Méndez & Belloni 2021), in the PDS up to 1250 Hz. However, we did not find any signs of such features in the PDS.…”

Section: Nature Of the X-ray Sourcementioning

confidence: 99%

NICER observations of the black hole candidate MAXI J0637–430 during the 2019–2020 outburst

Jana

Jaisawal

Naik

et al. 2021

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present detailed timing and spectral studies of the black hole candidate MAXI J0637–430 during its 2019-2020 outburst using observations with the Neutron Star Interior Composition Explorer (NICER) and the Neil Gehrels Swift Observatory. We find that the source evolves through the soft-intermediate, high-soft, hard-intermediate and low-hard states during the outburst. No evidence of quasi-periodic oscillations is found in the power density spectra of the source. Weak variability with fractional rms amplitude $<5{{\ \rm per\ cent}}$ is found in the softer spectral states. In the hard-intermediate and hard states, high variability with the fractional rms amplitude of $>20{{\ \rm per\ cent}}$ is observed. The 0.7 − 10 keV spectra with NICER are studied with a combined disk-blackbody and nthcomp model along with the interstellar absorption. The temperature of the disc is estimated to be 0.6 keV in the rising phase and decreased slowly to 0.1 keV in the declining phase. The disc component was not detectable or absent during the low hard state. From the state-transition luminosity and the inner edge of the accretion flow, we estimate the mass of the black hole to be in the range of 5–12 M⊙, assuming the source distance of d < 10 kpc.

show abstract

Section: Nature Of the X-ray Sourcementioning

confidence: 99%

NICER observations of the black hole candidate MAXI J0637–430 during the 2019–2020 outburst

Jana

Jaisawal

Naik

et al. 2021

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…For quadrupolar and quadrudipolar configurations, there are pronounced differences in the flows impacting the two different hemispheres: observer inclination would then be even more important in determining whether the detected emission is pulsed. We also find high levels of variability in the channeled accretion flows, something that may contribute to the high frequency variability and timing noise in X-ray emission from accreting neutron stars (see for example Hartman et al 2008;Bachetti et al 2010;Patruno & Watts 2021;Méndez & Belloni 2021). There are also implications for future attempts to do pulse profile modeling to measure mass and radius of accreting neutron stars.…”

Section: Discussionmentioning

confidence: 76%

GRMHD Simulations of Accreting Neutron Stars with Non-Dipole Fields

Das,

Porth,

Watts

2022

Preprint

View full text Add to dashboard Cite

NASA's NICER telescope has recently provided evidence for non-dipolar magnetic field structures in rotation-powered millisecond pulsars. These stars are assumed to have gone through a prolonged accretion spin-up phase, begging the question of what accretion flows onto stars with complex magnetic fields would look like. We present results from a suite of GRMHD simulations of accreting neutron stars for dipole, quadrupole, and quadrudipolar stellar field geometries. This is a first step towards simulating realistic hotspot shapes in a general relativistic framework to understand hotspot variability in accreting millisecond pulsars. We find that the location and size of the accretion columns resulting in hotspots changes significantly depending on initial stellar field strength and geometry. We also find that the strongest contributions to the stellar torque are from disk-connected fieldlines and the pulsar wind, leading to spin-down in almost all of the parameter regime explored here. We further analyze angular momentum transport in the accretion disk due to large scale magnetic stresses, turbulent stresses, wind-and compressible effects which we identify with convective motions. The disk collimates the initial open stellar flux forming jets. For dipoles, the diskmagnetosphere interaction can either enhance or reduce jet power compared to the isolated case. However for quadrupoles, the disk always leads to an enhanced net open flux making the jet power comparable to the dipolar case. We discuss our results in the context of observed neutron star jets and provide a viable mechanism to explain radio power both in the low-and high-magnetic field case.

show abstract

“…The observations indicate that the frequencies of these QPOs are related to the NS spins (Wang et al 2018), which also show the monotonically increasing trend along the atoll tracks (e.g., van Straaten et al 2000;Di Salvo et al 2001van Straaten et al 2003;Altamirano et al 2008), or along the Z tracks (e.g., van der Klis et al 1996;Wijnands et al 1997aWijnands et al , 1998aWijnands et al , 1998bJonker et al 1998;Homan et al 2002;Jonker et al 2002;Lin et al 2012). It is widely accepted in theory that kHz QPOs could be associated with the reaction of the accretion disk (Méndez & Belloni 2021;Miller 2021), and their emissions may be affected by the extreme gravitational field Abramowicz et al 2003aAbramowicz et al , 2003bKluźniak et al 2004;Kluźniak 2005), or the strong magnetic field (Miller et al 1998;Lamb & Miller 2001;Zhang 2004) around NS.…”

Section: Introductionmentioning

confidence: 89%

Exploring the Accretion Disk Structure and X-ray Radiation of GX 17+2 Based on kHz QPOs and Cross-correlations

Wang¹,

Zhang²,

Lei³

2022

Res. Astron. Astrophys.

View full text Add to dashboard Cite

Applying the timing tools of kilohertz quasi-periodic oscillations (kHz QPOs) and cross-correlations, we study the influence of the magnetosphere-disk relation on the X-ray radiation process of GX 17+2. First, as the spectral state track of X-ray emission evolves along the horizontal branch (HB), the magnetosphere-disk radii of the source derived by kHz QPOs shrink from r ∼ 24 km to r ∼ 18 km, while its average X-ray intensities in < 10 keV and in > 10 keV show the opposite evolutional trends. Moreover, this branch has been detected with the anti-correlations between the low-/high-energy (e.g., 2−5 keV/16−30 keV) X-rays. We suggest that in HB there may exist a X-ray radiation transfer process at the disk radii near the neutron star (NS), i.e., ∼ 5 − 10 km away from the surface, which probably originate from the interaction between the corona or jet with high-energy X-rays and accretion disk with low-energy X-rays. Second, as the source evolves along the normal branch (NB) and along the flaring branch (FB), their average X-ray intensities in all ∼ 2 − 30 keV show the monotonously decreasing and monotonously increasing trends, respectively. In addition, these two branches are both dominated by the positive correlations between the low- and high-energy (e.g., 2 − 5 keV/16 − 30 keV) X-rays. Moreover, the evolution along NB is accompanied by the shrinking of the magnetosphere-disk radii from r ∼ 18 km to r ∼ 16 km. We ascribe these phenomena to that as the shrinking of the accretion disk radius, the piled up accretion matter around the NS surface may trigger the radiation that produces both the low- and high-energy X-rays simultaneously, and then form the branches of NB and FB.

show abstract

High-Frequency Variability in Neutron-Star Low-Mass X-ray Binaries

Cited by 13 publications

References 176 publications

NICER observations of the black hole candidate MAXI J0637–430 during the 2019–2020 outburst

NICER observations of the black hole candidate MAXI J0637–430 during the 2019–2020 outburst

GRMHD Simulations of Accreting Neutron Stars with Non-Dipole Fields

Exploring the Accretion Disk Structure and X-ray Radiation of GX 17+2 Based on kHz QPOs and Cross-correlations

Contact Info

Product

Resources

About