Radio spectrum of the AXP J1810−197 and of its profile components

Lazaridis, K.; Jessner, A.; Krämer, M.; Stappers, B. W.; Lyne, A. G.; Jordan, C.; Serylak, M.; Zensus, J. A.

doi:10.1111/j.1365-2966.2008.13794.x

Cited by 58 publications

(73 citation statements)

References 22 publications

(45 reference statements)

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“…In addition to the LOFAR observations detailed above, we also present the results of our analysis on data at 328 MHz and 1380 MHz from the Westerbork Synthesis Radio Telescope (WSRT, Edwards & Stappers 2003), 624 MHz data from the Giant Meterwave Radio Telescope (GMRT, Gajjar et al 2012), 820 MHz data from the Green Bank Telescope (GBT, Rosen & Demorest 2011), previously unpublished 4850 MHz data from the Effelsberg telescope (see Lazaridis et al 2008, for details of the system) and new 2220 MHz data from WSRT (see Karuppusamy et al 2008, for details of the system). Full details of all of the observations are summarised in Table 1.…”

Section: Observationsmentioning

confidence: 99%

Differential frequency-dependent delay from the pulsar magnetosphere

Hassall

Stappers

Weltevrede

et al. 2013

A&A

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Some radio pulsars show clear "drifting subpulses", in which subpulses are seen to drift in pulse longitude in a systematic pattern. Here we examine how the drifting subpulses of PSR B0809+74 evolve with time and observing frequency. We show that the subpulse period (P 3 ) is constant on timescales of days, months and years, and between 14-5100 MHz. Despite this, the shapes of the driftbands change radically with frequency. Previous studies have concluded that, while the subpulses appear to move through the pulse window approximately linearly at low frequencies (<500 MHz), a discrete step of ∼180• in subpulse phase is observed at higher frequencies (>820 MHz) near to the peak of the average pulse profile. We use LOFAR, GMRT, GBT, WSRT and Effelsberg 100-m data to explore the frequency-dependence of this phase step. We show that the size of the subpulse phase step increases gradually, and is observable even at low frequencies. We attribute the subpulse phase step to the presence of two separate driftbands, whose relative arrival times vary with frequency -one driftband arriving 30 pulses earlier at 20 MHz than it does at 1380 MHz, whilst the other arrives simultaneously at all frequencies. The drifting pattern which is observed here cannot be explained by either the rotating carousel model or the surface oscillation model, and could provide new insight into the physical processes happening within the pulsar magnetosphere.

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Section: Observationsmentioning

confidence: 99%

Differential frequency-dependent delay from the pulsar magnetosphere

Hassall

Stappers

Weltevrede

et al. 2013

A&A

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“…One unusual aspect of radio emission from XTEJ1810−197 is the fluctuation on ∼daily timescales of its period-averaged flux density, which is largely intrinsic to the pulsar (e.g., Lazaridis et al 2008). These variations result from a combination of different pulse profile components becoming active (i.e., because of radically changing profiles) and varying intensity from particular components.…”

Section: Radio Flux Densitiesmentioning

confidence: 99%

“…It is unclear when radio emission started, but pulsations were not present in 1998 and a point source was visible by early 2004 . Radio pulsations were detected in early 2006 (Camilo et al 2006), with some properties that are markedly different from those of ordinary rotation-powered pulsars, including extremely variable flux densities and pulse profiles, and flat spectra (e.g., Camilo et al 2007c;Lazaridis et al 2008). The emission is also highly linearly polarized, like that of several ordinary young radio pulsars (Camilo et al 2007d;Kramer et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Radio Disappearance of the Magnetar Xte J1810–197 and Continued X-Ray Timing

Camilo

Ransom

Halpern

et al. 2016

ApJ

135

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We report on timing, flux density, and polarimetric observations of the transient magnetar and 5.54 s radio pulsar XTEJ1810−197 using the Green Bank, Nançay, and Parkes radio telescopes beginning in early 2006, until its sudden disappearance as a radio source in late 2008. Repeated observations through 2016 have not detected radio pulsations again. The torque on the neutron star, as inferred from its rotation frequency derivativeṅ, decreased in an unsteady manner by a factor of three in the first year of radio monitoring, until approximately mid-2007. By contrast, during its final year as a detectable radio source, the torque decreased steadily by only 9%. The periodaveraged flux density, after decreasing by a factor of 20 during the first 10 months of radio monitoring, remained relatively steady in the next 22 months, at an average of 0.7±0.3 mJy at 1.4 GHz, while still showing day-to-day fluctuations by factors of a few. There is evidence that during this last phase of radio activity the magnetar had a steep radio spectrum, in contrast to earlier flat-spectrum behavior. No secular decrease presaged its radio demise. During this time, the pulse profile continued to display large variations; polarimetry, including of a new profile component, indicates that the magnetic geometry remained consistent with that of earlier times. We supplement these results with X-ray timing of the pulsar from its outburst in 2003 up to 2014. For the first 4 years, XTEJ1810 −197 experienced non-monotonic excursions in frequency derivative by at least a factor of eight. But since 2007, itsṅ has remained relatively stable near its minimum observed value. The only apparent event in the X-ray record that is possibly contemporaneous with the radio shutdown is a decrease of ≈20% in the hot-spot flux in 2008-2009, to a stable, minimum value. However, the permanence of the high-amplitude, thermal X-ray pulse, even after the (unexplained) radio demise, implies continuing magnetar activity.

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“…Most recent distance and corresponding peak luminosity estimates for this source are d = 5 kpc, L X = 1.3 × 10 36 erg s −1 (Ibrahim et al 2004), d = 3.3 kpc, L X = 5.8 × 10 35 erg s −1 (Lazaridis et al 2008), and d = 3.5 kpc, L X = 6.6 × 10 35 erg s −1 (Bernardini et al 2009). In our calculations, we take d = 3.5 kpc.…”

Section: Application Of the Model To The X-ray Enhancement Light Curvmentioning

confidence: 99%

On the X-Ray Outbursts of Transient Anomalous X-Ray Pulsars and Soft Gamma-Ray Repeaters

Çalışkan¹,

Ertan²

2012

ApJ

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We show that the X-ray outburst light curves of four transient anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), namely, XTE J1810−197, SGR 0501+4516, SGR 1627−41, and CXOU J164710.2−455216, can be produced by the fallback disk model that was also applied to the outburst light curves of persistent AXPs and SGRs in our earlier work. The model solves the diffusion equation for the relaxation of a disk that has been pushed back by a soft gamma-ray burst. The sets of main disk parameters used for these transient sources are very similar to each other and to those employed in our earlier models of persistent AXPs and SGRs. There is a characteristic difference between the X-ray outburst light curves of transient and persistent sources. This can be explained by the differences in the disk surface density profiles of the transient and persistent sources in quiescence indicated by their quiescent X-ray luminosities. Our results imply that a viscous disk instability operating at a critical temperature in the range of ∼1300-2800 K is a common property of all fallback disks around AXPs and SGRs. The effect of the instability is more pronounced and starts earlier for the sources with lower quiescent luminosities, which leads to the observable differences in the X-ray enhancement light curves of transient and persistent sources. A single active disk model with the same basic disk parameters can account for the enhancement phases of both transient and persistent AXPs and SGRs. We also present a detailed parameter study to show the effects of disk parameters on the evolution of the X-ray luminosity of AXPs and SGRs in the X-ray enhancement phases.

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Radio spectrum of the AXP J1810−197 and of its profile components

Cited by 58 publications

References 22 publications

Differential frequency-dependent delay from the pulsar magnetosphere

Differential frequency-dependent delay from the pulsar magnetosphere

Radio Disappearance of the Magnetar Xte J1810–197 and Continued X-Ray Timing

On the X-Ray Outbursts of Transient Anomalous X-Ray Pulsars and Soft Gamma-Ray Repeaters

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