Photon Bubble Oscillations in Accretion-powered Pulsars

Klein, Richard; Arons, Jonathan; Jernigan, G.; Hsu, Jonathan Y.

doi:10.1086/309897

Cited by 65 publications

(58 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Proposed mechanisms include flow in a spatially inhomogeneous magnetic field (Underhill & Fahey 1984) and multi-periodic non-radial pulsations (Kaufer et al 2006), the latter possibly excited by near surface convection zones from opacity peaks (Cantiello et al 2009). In at least one source (HD 64760), the spectral line variability can be accounted for if the spots do not corotate with the stellar surface (Lobel & Blomme 2008), lending support to the multi-periodic non-radial pulsation hypothesis. From our results, the RMI is a clear candidate as a source of such pulsations.…”

Section: Large-scale Variabilitymentioning

confidence: 87%

Nonlinear Evolution of the Radiation-Driven Magneto-Acoustic Instability

Fernández

Socrates²

2013

ApJ

View full text Add to dashboard Cite

We examine the nonlinear development of unstable magnetosonic waves driven by a background radiative flux-the radiation-driven magneto-acoustic instability (RMI, a.k.a. the "photon bubble" instability). The RMI may serve as a persistent source of density, radiative flux, and magnetic field fluctuations in stably stratified, optically thick media. The conditions for instability are present in a variety of astrophysical environments and do not require the radiation pressure to dominate or the magnetic field to be strong. Here, we numerically study the saturation properties of the RMI, covering three orders of magnitude in the relative strength of radiation, magnetic field, and gas energies. Two-dimensional, time-dependent radiation-magnetohydrodynamic simulations of local, stably stratified domains are conducted with Zeus-MP in the optically thick, highly conducting limit. Our results confirm the theoretical expectations of Blaes & Socrates in that the RMI operates even in gas-pressure-dominated environments that are weakly magnetized. The saturation amplitude is a monotonically increasing function of the ratio of radiation to gas pressure. Keeping this ratio constant, we find that the saturation amplitude peaks when the magnetic pressure is comparable to the radiation pressure. We discuss the implications of our results for the dynamics of magnetized stellar envelopes, where the RMI should act as a source of sub-photospheric perturbations.

show abstract

Section: Large-scale Variabilitymentioning

confidence: 87%

Nonlinear Evolution of the Radiation-Driven Magneto-Acoustic Instability

Fernández

Socrates²

2013

ApJ

View full text Add to dashboard Cite

show abstract

“…Different physical effects can appear in this zone, e.g. 'photon bubble oscillations' discussed in [14,15]. …”

Section: Basic Equationsmentioning

confidence: 99%

Continuum correlations in accreting X-ray pulsars

Gornostaev

Постнов

Klochkov

2016

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Abstract. Two-dimensional structure of accretion columns in the radiation-diffusion limit is calculated for two possible geometries (filled and hollow cylinder) for mass accretion ratesṀ ranging from 10 17 to 1.2 × 10 18 g s −1 . The observed spectral hardening in the transient X-ray pulsars with increasingṀ can be reproduced by a Compton-saturated sidewall emission from optically thick magnetized accretion columns with taking into account the emission reflected from the neutron star atmosphere. AtṀ above some critical valueṀcr ∼ (6 − 8) × 10 17 g s −1 , the height of the column becomes such that the contribution of the reflected component to the total emission starts decreasing, which leads to the saturation and even slight decrease of the spectral hardness. Hollow-cylinder columns have a smaller height than the filled-cylinder ones, and the contribution of the reflected component in the total emission does not virtually change withṀ (and hence the hardness of the continuum monotonically increases) up to higher mass accretion rates thanṀcr for the filled columns. ObservationsAfter the discovery of X-ray pulsars in 1971 [1] it was realized that in bright pulsars the radiation plays a crucial role in braking of the accreting matter onto the surface of a neutron star with strong magnetic field. It is now well recognized that once the radiation density above the polar cap starts playing the role in the accreting matter dynamics, an optically thick accretion column above the polar cap is formed [2] (see [3] for the latest investigation). The characteristic height of the column increases with accretion rate, most of the emission escapes through sidewalls, and it can be expected that above some X-ray luminosity the dependence of the observed properties of the continuum emission on the X-ray luminosity can become different from that in the lowluminosity regime.Indeed, a similar bimodality is observed in the dependence of the X-ray continuum hardness on luminosity. This dependence can be studied using, for example, data from all-sky monitors such as RXTE/ASM and MAXI, i.e. without dedicated spectroscopic observations which are necessary to measure CRSFs. Following this approach, we measured the hardness ratio as a function of luminosity in the accreting pulsars GX 304−1, 4U 0115+63, V 0332+53, EXO 2030+375, A 0535+26 and MXB 0656−072 using the data from different energy bands of RXTE/ASM. The result is shown in Fig. 1. To convert the ASM count rates into X-ray luminosities, we used published distances to the sources (GX 304−1: ∼2 kpc, [4];

show abstract

“…The model stands out by not requiring rotational phenomena to explain the QPOs, and does not naturally produce beat frequencies. In recent work, attention with respect to this model has shifted to the classical accreting pulsars for which it was originally conceived (Klein et al 1996a;Section 6.2).…”

Section: Photon Bubble Modelmentioning

confidence: 99%

Millisecond Oscillations in X-Ray Binaries

Klis

2000

Annu. Rev. Astron. Astrophys.

510

View full text Add to dashboard Cite

Key Words neutron stars, black holes, relativity, X-ray binaries, pulsars, quasi-periodic oscillations s Abstract The first millisecond X-ray variability phenomena from accreting compact objects have recently been discovered with the Rossi X-ray Timing Explorer. Three new phenomena are observed from low-mass X-ray binaries containing lowmagnetic-field neutron stars: millisecond pulsations, burst oscillations, and kilohertz quasi-periodic oscillations. Models for these new phenomena involve the neutron star spin and orbital motion close around the neutron star, and rely explicitly on our understanding of strong gravity and dense matter. I review the observations of these new neutron-star phenomena and some possibly related phenomena in black-hole candidates, and describe the attempts to use these observations to perform measurements of fundamental physical interest in these systems.

show abstract

Photon Bubble Oscillations in Accretion-powered Pulsars

Cited by 65 publications

References 12 publications

Nonlinear Evolution of the Radiation-Driven Magneto-Acoustic Instability

Nonlinear Evolution of the Radiation-Driven Magneto-Acoustic Instability

Continuum correlations in accreting X-ray pulsars

Millisecond Oscillations in X-Ray Binaries

Contact Info

Product

Resources

About