Scatter broadening of pulsars in the direction of the Gum nebula

Mitra, Dipanjan; Ramachandran, R.

doi:10.1051/0004-6361:20010274

Cited by 17 publications

(34 citation statements)

References 16 publications

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“…This was first discussed by Mitra et al (2003), following earlier work on the effect of HII regions and OB stars on the dispersion measure (DM) of PSR by Prentice & Ter Haar (1969), Grewing & Walmsley (1971), and in an earlier paper by Mitra & Ramachandran (2001). Several discussions of such observed or suspected RM anomalies can be found in the literature (see e.g., Rand & Kulkarni 1989;Han et al 1999;Brown & Taylor 2001).…”

Section: The Reliability Of the Rm Estimatesmentioning

confidence: 91%

The large-scale magnetic field in the fourth Galactic quadrant

Nota¹,

Katgert²

2010

A&A

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Aims. We have re-examined the published rotation measures (RMs) of extragalactic point sources and pulsars with |b| < 3 • to study the magnetic field in the fourth Galactic quadrant. Methods. We reduced the influence of structure in electron density as much as possible by excluding objects for which Hα-data indicate large fluctuations in n e somewhere along the line of sight. We also excluded objects for which the RM may have been significantly "corrupted" by an intervening supernova remnant. We modeled RM(l), the longitude dependence of RM of the unaffected extragalactic sources and pulsars. We assumed several geometries for the large-scale field. All but one of those are based on logarithmic spiral arms (with various pitch angles and widths), while one has circular symmetry. We also made different assumptions about the large-scale n e -distribution. Results. The data suggest the following generic behaviour of the large-scale field in the 4th Galactic quadrant. The field is most likely organized along logarithmic spiral arms and shows two significant reversals: from the Norma arm (CCW field) to the Norma-Crux interarm region (CW field), and from the Norma-Crux interarm region to the Crux arm (CCW field). The present data do not constrain the field in and beyond the Crux-Carina interarm region. Although the models give a good description of the global character of RM(l), individual RM-estimates deviate by typically 15 times their measurement errors. We argue that these large deviations are most likely due to the "small-scale" field that dominates on scales of up to several hundred pc. Conclusions. The picture that emerges is thus of a field that has significant structure on smaller scales, but for which the average values in arms and interarm regions are nevertheless well-defined. In addition, this smaller-amplitude large-scale field appears to reverse at each arm-interarm boundary that we can study with the present data. We briefly discuss the link between these results and theoretical predictions.

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Section: The Reliability Of the Rm Estimatesmentioning

confidence: 91%

The large-scale magnetic field in the fourth Galactic quadrant

Nota¹,

Katgert²

2010

A&A

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“…While the estimate given by the empirical relation in Eq. (2) is a good description of the general tendency against DM, for a given DM they can differ by more than one magnitude (Mitra & Ramachandran 2001;Ramachandran et al 1997). Obviously when τ sc increases, the PA curves can be completely flattened irrespective of the original PA curve shape.…”

Section: Scattering Effect On Observed Pulsar Profilesmentioning

confidence: 98%

The effect of scattering on pulsar polarization angle

Han

2003

A&A

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Abstract. The low-frequency profiles of some pulsars manifest temporal broadening due to scattering, usually accompanied by flat polarization position angle (PA) curves. Assuming that the scattering works on the 4 Stokes parameters in the same way, we have simulated the effect of scattering on polarization profiles and find that the scattering can indeed flatten the PA curves. Since the higher-frequency profiles suffer less from scattering, they are convolved with scattering models to fit the observed low-frequency profiles. The calculated flat PA curves exactly reproduce the corresponding observations.

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“…Based on the radio dispersion measure of the pulsar (DM = 239 cm −3 pc; Kramer et al 2003) combined with the NE2001 model of Galactic electron distribution from Cordes & Lazio (2002), the distance to the pulsar is estimated to be 4 kpc. However, estimating the distance with this method in this specific region of the sky can be erroneous (see Mitra & Ramachandran 2001) due to the structured and nearby emission of the Gum nebula, a 35…”

Section: Introductionmentioning

confidence: 99%

A new nearby pulsar wind nebula overlapping the RX J0852.0−4622 supernova remnant

Acero

Gallant

Ballet

et al. 2013

A&A

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Context. Energetic pulsars can be embedded in a nebula of relativistic leptons that is powered by the dissipation of the rotational energy of the pulsar. The object PSR J0855−4644 is an energetic and fast-spinning pulsar (Ė = 1.1 × 10 36 erg s −1 , P = 65 ms) discovered near the southeast rim of the supernova remnant (SNR) RX J0852.0−4622 (aka Vela Jr) by the Parkes multibeam survey. The position of the pulsar is in spatial coincidence with an enhancement in X-rays and TeV γ-rays, which could be due to its putative pulsar wind nebula (PWN). Aims. The purpose of this study is to search for diffuse non-thermal X-ray emission around PSR J0855−4644 to test for the presence of a PWN and to estimate the distance to the pulsar.Methods. An X-ray observation was carried out with the XMM-Newton satellite to constrain the properties of the pulsar and its nebula. The absorption column density derived in X-rays from the pulsar and from different regions of the SNR rim was compared with the absorption derived from the atomic (HI) and molecular ( 12 CO) gas distribution along the corresponding lines of sight to estimate the distance to the pulsar and to the SNR. Results. The observation has revealed the X-ray counterpart of the pulsar together with surrounding extended emission, thus confirming the existence of a PWN. The comparison of column densities provided an upper limit to the distance to the pulsar PSR J0855−4644 and the SNR RX J0852.0−4622 (d ≤ 900 pc). Although both objects are at compatible distances, we rule out that the pulsar and the SNR are associated. With this revised distance, PSR J0855−4644 is the second most energetic pulsar, after the Vela pulsar, within a radius of 1 kpc and could therefore contribute to the local cosmic-ray e − /e + spectrum.

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Scatter broadening of pulsars in the direction of the Gum nebula

Cited by 17 publications

References 16 publications

The large-scale magnetic field in the fourth Galactic quadrant

The large-scale magnetic field in the fourth Galactic quadrant

The effect of scattering on pulsar polarization angle

A new nearby pulsar wind nebula overlapping the RX J0852.0−4622 supernova remnant

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