The outburst decay of the low magnetic field magnetar SWIFT J1822.3−1606: phase-resolved analysis and evidence for a variable cyclotron feature

Castillo, G. A. Rodríguez; Israel, G. L.; Tiengo, A.; Salvetti, D.; Turolla, R.; Zane, S.; Rea, N.; Esposito, P.; Mereghetti, S.; Perna, Rosalba; Stella, L.; Pons, José A.; Campana, S.; Götz, D.; Motta, S.

doi:10.1093/mnras/stv2490

Cited by 42 publications

(9 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, a phase-dependent absorption feature, present only for ∼ 20% of the pulsar rotation, was detected in the X-ray spectrum of RX J0720.4-3125 (Borghese et al 2015). Features with somewhat similar properties were previously reported in two low-field magnetars, SGR 0418+5729 and SWIFT J1822.3-1606 (Tiengo et al 2013;Rodríguez Castillo et al 2016), and, because of the strong dependence on the rotational phase, believed to be produced by proton cyclotron resonant scattering in a magnetic loop close to the star surface. According to magneto-thermal evolution models (Viganò et al 2013), XDINSs are likely to be the descendants of magnetars, therefore we expect to find similar spectral features which would provide evidence for a surface magnetic field structure more complex than a pure dipole .…”

Section: Introductionsupporting

confidence: 56%

“…For both RX J0720.4-3125 and RX J1308.6+2127 the feature is detected only in a narrow phase interval (∼ 20% of the pulsar rotation), the line energy is ∼ 750 eV, and the width is consistent with the spectral energy resolution of the pn camera, about 100 eV for single pixel events at the centroid energy. Interestingly a similar phase-variable absorption feature (although with a larger energy shift with phase) has been detected in two low-field magnetars, SGR 0418+5729 and SWIFT J1822.3-1606 (Tiengo et al 2013;Rodríguez Castillo et al 2016). In these sources the line energy is higher (≥ 2 keV) and shows a strong variation in phase, which is not evident in both XDINSs possibly because the source counts become background dominated at energies just above that of the feature (∼ 1 keV).…”

Section: Discussionmentioning

confidence: 55%

See 1 more Smart Citation

Narrow phase-dependent features in X-ray dim isolated neutron stars: a new detection and upper limits

Borghese

Rea

Zelati

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We report on the results of a detailed phase-resolved spectroscopy of archival XMM-Newton observations of X-ray Dim Isolated Neutron Stars (XDINSs). Our analysis revealed a narrow and phase-variable absorption feature in the X-ray spectrum of RX J1308.6+2127. The feature has an energy of ∼740 eV and an equivalent width of ∼15 eV. It is detected only in ∼ 1/5 of the phase cycle, and appears to be present for the entire timespan covered by the observations (2001 December -2007. The strong dependence on the pulsar rotation and the narrow width suggest that the feature is likely due to resonant cyclotron absorption/scattering in a confined high-B structure close to the stellar surface. Assuming a proton cyclotron line, the magnetic field strength in the loop is B loop ∼ 1.7 × 10 14 G, about a factor of ∼5 higher than the surface dipolar magnetic field (B surf ∼ 3.4 × 10 13 G). This feature is similar to that recently detected in another XDINS, RX J0720.4-3125, showing (as expected by theoretical simulations) that small scale magnetic loops close to the surface might be common to many highly magnetic neutron stars (although difficult to detect with current X-ray instruments). Furthermore, we investigated the available XMM-Newton data of all XDINSs in search for similar narrow phase-dependent features, but could derive only upper limits for all the other sources.

show abstract

Section: Introductionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 55%

Narrow phase-dependent features in X-ray dim isolated neutron stars: a new detection and upper limits

Borghese

Rea

Zelati

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…INS showing magnetars bursts but with ordinary inferred dipole field strengths (see Turolla & Esposito 2013, for a review). These discoveries indicate that the dipole field strength is not the single parameter leading to the different manifestations favouring the early suggestions (Gavriil et al 2002;Ekşi & Alpar 2003;Ertan & Alpar 2003;McLaughlin et al 2003) that what causes the magnetar activity could be in the higher multipoles (Alpar et al 2011;Rodríguez Castillo et al 2016).…”

Section: Introductionmentioning

confidence: 85%

Classification of pulsars with Dirichlet process Gaussian mixture model

İnce

Kamasak

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Young isolated neutron stars (INS) most commonly manifest themselves as rotationally powered pulsars (RPPs) which involve conventional radio pulsars as well as gammaray pulsars (GRPs) and rotating radio transients (RRATs). Some other young INS families manifest themselves as anomalous X-ray pulsars (AXPs) and soft gammaray repeaters (SGRs) which are commonly accepted as magnetars, i.e. magnetically powered neutron stars with decaying super-strong fields. Yet some other young INS are identified as central compact objects (CCOs) and X-ray dim isolated neutron stars (XDINSs) which are cooling objects powered by their thermal energy. Older pulsars, as a result of a previous long episode of accretion from a companion, manifest themselves as millisecond pulsars and more commonly appear in binary systems. We use Dirichlet process Gaussian mixture model (DPGMM), an unsupervised machine learning algorithm, for analyzing the distribution of these pulsar families in the parameter space of period and period derivative. We compare the average values of the characteristic age, magnetic dipole field strength, surface temperature and transverse velocity of all discovered clusters. We verify that DPGMM is robust and provides hints for inferring relations between different classes of pulsars. We discuss the implications of our findings for the magneto-thermal spin evolution models and fallback discs.

show abstract

“…Recent observations of cyclotron emission from the weak-field magnetars SGR 0418+5729 and SWIFT J1822.3-1606 suggest the presence of small-scale magnetic loops near the stellar surface, which can be up to two orders of magnitude stronger than the spin-down inferred dipole field strength [Tiengo et al (2013), Rodríguez Castillo et al (2016)]. Such strong high-order magnetic multipoles may drive Hall drift on short timescales, and produce X-ray activity normally associated with classical magnetars.…”

Section: Discussionmentioning

confidence: 99%

Magnetic field evolution of neutron stars – I. Basic formalism, numerical techniques and first results

Bransgrove

Levin

Beloborodov

2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

In this work we explore the evolution of magnetic fields inside strongly magnetized neutron stars in axisymmetry. We model numerically the coupled field evolution in the core and the crust. Our code models the Hall drift and Ohmic effects in the crust, the back-reaction on the field from magnetically-induced elastic deformation of the crust, the magnetic twist exchange between the crust and the core, and the drift of superconducting flux tubes inside the core. The correct hydromagnetic equilibrium is enforced in the core. We find that i) The Hall attractor found by Gourgouliatos and Cumming in the crust exists also for configurations when the B-field penetrates into the core. However, the evolution timescale for the core-penetrating fields is dramatically different than that of the fields confined to the crust. ii) The combination of Jones' flux tube drift and Ohmic dissipation in the crust can deplete the pulsar magnetic fields on the timescale of 150 Myr if the crust is hot (T ∼ 2 × 10 8 K), but acts on much slower timescales for cold neutron stars, such as recycled pulsars (∼ 1.8 Gyr, depending on impurity levels). iii) The outward motion of superfluid vortices during the rapid spindown of a young highly magnetized pulsar, can result in a partial expulsion of flux from the core when B 10 13 G. However for B 2 × 10 13 G, the combination of a stronger magnetic field and a longer spin period implies that the core field cannot be expelled.

show abstract

The outburst decay of the low magnetic field magnetar SWIFT J1822.3−1606: phase-resolved analysis and evidence for a variable cyclotron feature

Cited by 42 publications

References 31 publications

Narrow phase-dependent features in X-ray dim isolated neutron stars: a new detection and upper limits

Narrow phase-dependent features in X-ray dim isolated neutron stars: a new detection and upper limits

Classification of pulsars with Dirichlet process Gaussian mixture model

Magnetic field evolution of neutron stars – I. Basic formalism, numerical techniques and first results

Contact Info

Product

Resources

About