Michael Kramer

The High Time Resolution Universe survey – IX. Polarimetry of long-period pulsars

We present a polarimetric analysis of 49 long-period pulsars discovered as part of the High Time Resolution Universe (HTRU) southern survey. The sources exhibit the typical characteristics of “old” pulsars, with low fractional linear and circ ular polarisation and narrow, multicomponent profiles. Although the position angle swings are g enerally complex, for two of the analysed pulsars (J1622 3751 and J1710 2616) we obtained an indication of the geometry via the rotating vector model. We were able to determine a value of the rotation measure (RM) for 34 of the sources which, when combined with their dispersion measures (DM), yields an integrated magnetic field strength along the line of sight. W ith the data presented here, the total number of values of RM associated to pulsars discovered during the HTRU southern survey sums to 51. The RMs are not consistent with the hypothesis of a counter-clockwise direction of the Galactic magnetic field within an annulus in cluded between 4 and 6 kpc from the Galactic centre. A partial agreement with a counter-clockwise sense of the Galactic magnetic field within the spiral arms is however found in the area of the Carina-Sagittarius arm.

Pulsars - Enabling the Gravitation KSP of the SKA

In a SKADS funded study we have investigated the impact of the SKA design on the prospects to achieve the scientific goals outlined in the Key Science Project on testing gravity using pulsars and black holes. We find that the computing requirements are severe and differ for individual configurations. As today, pulsar science will continue to be limited by the available computing power. However, we present methods to achieve the science goals but point out that every reduction in sensitivity (i.e. A/T ) will severely risk the success of this KSP. Unlike other observing modes, we cannot trade collecting area for field-ofview or integration time. This important feature is potentially the most important factor to be considered for pulsar studies when

An Update on TRAPUM

TRansients and PUlsars with MeerKAT (TRAPUM) is a n MeerKAT Large Survey Project which will utilise MeerKAT to n greatly expand our knowledge of the populations of sources which n emit at radio wavelengths on timescales ranging from n microseconds to seconds. The excellent sensitivity of MeerKAT n will allow us to discover many new (millisecond) pulsars, fast n radio transients including FRBs, radio emitting magnetars, n RRATs, giant pulses, flare stars, and active binaries to name n just a few. It will also allow us to significantly expand the n parameter space over which radio transients have been n discovered. MeerKAT will also be excellent for localising and n new sources through the combination of the relatively long n baselines and the use of transient buffers. TRAPUM will achieve n this through a combination of targeted searches: directed at n gamma-ray emitters identified by Fermi, supernova remnants n and other high energy sources, globular clusters -- reservoirs of n pulsars, and the Galactic centre, and blind searches of regions n of the Galactic plane. It will also perform a wide area Flys n Eye style search for fast transients that will be able to find n at least 30 of the brightest FRBs. These searches are enabled by n MeerKAT in combination with a 400-beam beamformer and real-time n and offline processing capabilities funded through the n Max-Planck-Institut fur Radioastronomie and the European n Research Council-funded MeerTRAP project. This contribution is n completed on behalf of the entire TRAPUM team which consists of n more than 40 members from across the world. See n www.trapum.org for up to date team membership and other n information.

A pulsar wind nebula associated with PSR J2032+4127 as the powering source of TeV J2032+4130

The very-high-energy gamma-ray source TeV J2032+4130, in the Cygnus region, was the first source discovered of a population of extended TeV sources without low-frequency counterparts. In its field there is a pulsar, namely PSR J2032+4127, which has been detected by Fermi in gamma-rays and in radio by the Green Bank Telescope (GBT). We report on an ongoing multiwavelength campaign to search for a pulsar wind nebula associated with PSR J2032+4127 through radio and X-ray observations. Moreover, we are conducting a multi-epoch very long baseline interferometr (VLBI) campaign with the European VLBI network (EVN) in order to measure the pulsar proper motion and to find its relation with the radio nebula and the TeV extended source. All these results together, combined with a theoretical modeling of the system, enable us to propose a conceivable physical scenario in which the extended radio, X-ray and TeV emissions are accounted for.

Study of scattering material with RadioAstron-VLBI observations

The RadioAstron spacecraft presents an unique opportunity to measure properties of interstellar scattering. Pulsars offer a variety of observables for study of interstellar scattering. Observations of scattering of nearby pulsars and intra-day variable quasars point to the existence of a component of the interstellar medium (ISM) which has properties quite different from the more distant, diffuse ISM. We observed several nearby pulsars as part of RadioAstron’s Early Science Program (ESP). These included pulsars B0950+08, B1919+21 and B0329+54. We present here some results concerning the distribution and properties of scattering material in the direction to these pulsars obtained with cosmic interferometer.

Pulsar Rotation Measures and the Large-Scale Magnetic Structure of the Milky Way

Faraday rotation measures (RMs) of polarised pulsar emissi on and extragalactic sources present the most efficient observable for determining the configurat ion of the magnetic field of the Galaxy, both in its plane and at high latitudes. Reconstructions of t he Galactic magnetic field (GMF) allow a deeper understanding of numerous astrophysical pro cesses in the interstellar medium and even of the cosmological microwave background. LOFAR (the L Ow Frequency ARray) will soon embark on an all-sky pulsar survey, which will return hu dreds of new pulsar discoveries. In addition, the High Time Resolution Universe survey is als o currently searching for pulsars, at higher frequencies. The subsequent RM data from any pulsa rs discovered in these surveys, together with the current sample, will provide unprecedent ed coverage of the Galactic plane and halo. We present our plans to select an appropriate sample of ulsar RMs for use with the powerful method of wavelet tomography. In addition, we show first simu lations of how additional RM values improve the wavelet-based reconstruction of the kpc -scale GMF.

Detection of the Fermi/GBT pulsar PSR J2032+4127 with the EVN and the DiFX correlator in Bonn

We observed the Fermi/GBT pulsar PSR J2032+4127 with the EVN at 1.6 GHz in March 2010. The source has a period-averaged flux density of 0.18 mJy and a duty cycle of approximately 10% at this frequency. To obtain a good position of the source, we observed it using phase referencing with 6 EVN antennas at 1 Gbps, and we correlated the data using pulsar gating in the new DiFX correlator in Bonn. A preliminary data reduction shows that the faint pulsar was detected with a signal-to-noise ratio of 8, with an improvement of a factor of 2 thanks to the use of pulsar gating. This has provided the first accurate VLBI position of this radio pulsar. Future EVN observations will allow us to obtain an accurate proper motion of PSR J2032+4127, which will shed light to the possible association of this pulsar with the unidentified very-high-energy gamma-ray source TeV J2032+4130.