Wide-band Simultaneous Observations of Pulsars: Disentangling Dispersion
Measure and Profile Variations
ArXiv 1204.3864 (2012)
Authors:
TE Hassall, BW Stappers, JWT Hessels, M Kramer, A Alexov, K Anderson, T Coenen, A Karastergiou, EF Keane, VI Kondratiev, K Lazaridis, J van Leeuwen, A Noutsos, M Serylak, C Sobey, JPW Verbiest, P Weltevrede, K Zagkouris, R Fender, RAMJ Wijers, L Bahren, ME Bell, JW Broderick, S Corbel, EJ Daw, VS Dhillon, J Eisloffel, H Falcke, J-M Griessmeier, P Jonker, C Law, S Markoff, JCA Miller-Jones, R Osten, E Rol, AMM Scaife, B Scheers, P Schellart, H Spreeuw, J Swinbank, S ter Veen, MW Wise, R Wijnands, O Wucknitz, P Zarka, A Asgekar, MR Bell, MJ Bentum, G Bernardi, P Best, A Bonafede, AJ Boonstra, M Brentjens, WN Brouw, M Bruggen, HR Butcher, B Ciardi, MA Garrett, M Gerbers, AW Gunst, MP van Haarlem, G Heald, M Hoeft, H Holties, A de Jong, LVE Koopmans, M Kuniyoshi, G Kuper, GM Loose, P Maat, J Masters, JP McKean, H Meulman, M Mevius, H Munk, JE Noordam, E Orru, H Paas, M Pandey-Pommier, VN Pandey, R Pizzo, A Polatidis, W Reich, H Rottgering, J Sluman, M Steinmetz, CGM Sterks, M Tagger, Y Tang, C Tasse, R Vermeulen, RJ van Weeren, SJ Wijnholds, S Yatawatta
Abstract:
Dispersion in the interstellar medium is a well known phenomenon that follows
a simple relationship, which has been used to predict the time delay of
dispersed radio pulses since the late 1960s. We performed wide-band
simultaneous observations of four pulsars with LOFAR (at 40-190 MHz), the 76-m
Lovell Telescope (at 1400 MHz) and the Effelsberg 100-m Telescope (at 8000 MHz)
to test the accuracy of the dispersion law over a broad frequency range. In
this paper we present the results of these observations which show that the
dispersion law is accurate to better than 1 part in 100000 across our observing
band. We use this fact to constrain some of the properties of the ISM along the
line-of-sight and use the lack of any aberration or retardation effects to
determine upper limits on emission heights in the pulsar magnetosphere. We also
discuss the effect of pulse profile evolution on our observations, and the
implications that it could have for precision pulsar timing projects such as
the detection of gravitational waves with pulsar timing arrays.
