Pulsar detection at 87 GHz

D. Morris , M. Kramer , C. Thum , R. Wielebinski , M.Grewing , J.Peñalver , A.Jessner , G. Butin , W. Brunswig
Institut de RadioAstronomie Millimétrique, 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121,Bonn, Germany
Instituto de Radioastronom´ıa Millimétrica,Avenida Divina Pastora 7, E-18012,Granada,Spain
Abstract: Pulsed radio emission at 87 GHz has been detected from the pulsar PSR B0355+54 (Fig. 2. The observed flux density of  mJy is, within the measurement errors, the same as measured previously at 43 GHz and is thus higher than expected. However the errors are such that all the measurements at frequencies higher than 1.2 GHz are just consistent with a single power law spectrum (Fig. 3.

A second pulsar, PSR B2021+51, with a reported excess of flux density at 43 GHz, has been observed but not detected. The resulting upper limit for the flux density provides little constraint on the form of its spectrum above 43 GHz.

  
Figure: Observed pulse profiles of PSR B0355+54 at several radio frequencies between 1.4 GHz and 87 GHz. Flux density on an arbitrary scale, and different for each frequency,has been plotted vertically. The time resolution is for frequencies between 1.4 and 14.6 GHz, s for 23.05 GHz and s for the 43 GHz observations.The 87 GHz profile represents the Pico Veleta measurement smoothed to a time resolution of 4 ms.

  
Figure 3: Pulse spectra for PSRs B0355+54. The measurements made at 87 GHz are presented as an open triangle and as an upper limit (at a 5 level), respectively. For references of flux densities at lower frequencies see text.