A new X-ray look into four old pulsars

Rigoselli, Michela; Mereghetti, S.

doi:10.1051/0004-6361/201732408

Cited by 21 publications

(18 citation statements)

References 36 publications

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“…In the case of PSR J0922+0638, τ ch = 0.5 Myr and τ kin = 1.6 Myr. X-ray observations showed only some indications for thermal emission from the polar cap, and did not detect any bulk X-ray radiation [230]. This confirms the old age of this pulsar (or alternatively, it is a massive NS that cooled down quickly).…”

Section: Ages Of Radio Pulsarssupporting

confidence: 53%

Evolution of Neutron Star Magnetic Fields

2021

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Neutron stars are natural physical laboratories allowing us to study a plethora of phenomena in extreme conditions. In particular, these compact objects can have very strong magnetic fields with non-trivial origin and evolution. In many respects, its magnetic field determines the appearance of a neutron star. Thus, understanding the field properties is important for the interpretation of observational data. Complementing this, observations of diverse kinds of neutron stars enable us to probe parameters of electro-dynamical processes at scales unavailable in terrestrial laboratories. In this review, we first briefly describe theoretical models of the formation and evolution of the magnetic field of neutron stars, paying special attention to field decay processes. Then, we present important observational results related to the field properties of different types of compact objects: magnetars, cooling neutron stars, radio pulsars, and sources in binary systems. After that, we discuss which observations can shed light on the obscure characteristics of neutron star magnetic fields and their behaviour. We end the review with a subjective list of open problems.

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Section: Ages Of Radio Pulsarssupporting

confidence: 53%

Evolution of Neutron Star Magnetic Fields

2021

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“…Absorption features reported in several isolated neutron stars of different types (e.g., Sanwal et al 2002;De Luca et al 2004;McLaughlin et al 2007;Kargaltsev et al 2012;Tiengo et al 2013;Borghese et al 2015;Rigoselli & Mereghetti 2018) have been interpreted either as a proton (or atomic) absorption in strongly magnetized atmosphere (photosphere) or as electron cyclotron absorption in the NS magnetosphere.…”

Section: Discussionmentioning

confidence: 99%

Possible Phase-dependent Absorption Feature in the X-Ray Spectrum of the Middle-aged PSR J0659+1414

Arumugasamy

Kargaltsev

Posselt

et al. 2018

ApJ

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We report on the energy-resolved timing and phase-resolved spectral analysis of X-ray emission from PSR J0659+1414 observed with XMM-Newton and NuSTAR. We find that the new data rule out the previously suggested model of the phase-dependent spectrum as a three-component (2 blackbodies + power-law) continuum, which shows large residuals between 0.3 − 0.7 keV. Fitting neutron star atmosphere models or several blackbodies to the spectrum does not provide a better description of the spectrum, and requires spectral model components with unrealistically large emission region sizes. The fits improve significantly if we add a phase-dependent absorption feature with central energy 0.5 − 0.6 keV and equivalent width up to ≈ 50 eV. We detected the feature for about half of the pulse cycle. Energy-resolved pulse profiles support the description of the spectrum with a three-component continuum and an absorption component. The absorption feature could be interpreted as an electron cyclotron line originating in the pulsar magnetosphere and broadened by the non-uniformity of magnetic field along the line of sight. The significant phase-variability in the thermal emission from the entire stellar surface may indicate multi-polar magnetic fields and a nonuniform temperature distribution. The strongly pulsed non-thermal spectral component detected with NuSTAR in the 3-20 keV range is well fit by a power-law model with a photon index Γ = 1.5 ± 0.2.

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“…The presence of a strong multipolar magnetic field is often invoked to explain X-ray thermal emission from areas that are apparently smaller than the polar cap area for a dipolar surface magnetic field. Recent compilations of polar cap radii from X-ray observed non-recycled pulsars have been used as strong observational evidence for a multipolar surface magnetic field (Geppert 2017;Rigoselli & Mereghetti 2018). We revisit the literature listed in these compilations and assess the robustness of their thermal polar cap area measurements.…”

Section: Discussionmentioning

confidence: 99%

“…Our goal is to obtain robust evidence for multipolar magnetic fields by performing a uniform analysis of thermal emission from non-recycled RPPs. There have been attempts to find evidence of multipolar magnetic fields by estimating the PC areas (Geppert 2017;Rigoselli & Mereghetti 2018). However, these works rely on a diverse body of literature, which suffers from one or more of a number of problems (See Section 7 for a detailed critique).…”

Section: Introductionmentioning

confidence: 99%

“…These are indicative of beamed (anisotropic) emission significantly deviating from a BB. For rest of the pulsars, either no tests were performed and/or no evidence found to prove the existence of a BB (B0943+10;Mereghetti et al 2016 Hermsen et al 2017, PSR B0355+54; Klingler et al 2016, PSR B0114+58;Rigoselli & Mereghetti 2018Kargaltsev et al 2012, PSR J2021+4026 Lin et al 2013).…”

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confidence: 99%

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Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

Arumugasamy

Mitra

2019

Monthly Notices of the Royal Astronomical Society

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PSR J0108-1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modeled with a power-law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the presence of phase-separated thermal and non-thermal components. The spectrum extracted from half the rotational phase away from the X-ray peak fits well with either a single blackbody (BB) or a neutron star atmosphere (NA) model, whereas, the spectrum from the rest of the phase range is dominated by a PL. From Bayesian analysis, the estimated BB area is smaller than the expected polar cap area for a dipolar magnetic field with a probability of 86% whereas the area estimate from the NA model is larger with a probability of 80%. Due to the ambiguity in the thermal emission model, the polar cap area cannot be reliably estimated and hence cannot be used to understand the nature of the surface magnetic field. Instead, we can infer the presence of multipolar magnetic field from the misalignment between the pulsar's thermal X-ray peak and the radio emission peak. For J0108-1431, we estimated a phase-offset ∆φ > 0.1 between the thermal polar cap emission peak and the radio emission peak and argue that this is best explained by the presence of a multipolar surface magnetic field.

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A new X-ray look into four old pulsars

Cited by 21 publications

References 36 publications

Evolution of Neutron Star Magnetic Fields

Evolution of Neutron Star Magnetic Fields

Possible Phase-dependent Absorption Feature in the X-Ray Spectrum of the Middle-aged PSR J0659+1414

Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

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