Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR

M. Pilla, B.W. Stappers, H. Falcke, I.M. Avruch, E. Bell, A.W. Gunst, Marinus Jan Bentum

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    Abstract

    Context: LOFAR offers the unique capability of observing pulsars across the 10−240 MHz frequency range with a fractional bandwidth of roughly 50%. This spectral range is well suited for studying the frequency evolution of pulse profile morphology caused by both intrinsic and extrinsic effects such as changing emission altitude in the pulsar magnetosphere or scatter broadening by the interstellar medium, respectively. Aims: The magnitude of most of these effects increases rapidly towards low frequencies. LOFAR can thus address a number of open questions about the nature of radio pulsar emission and its propagation through the interstellar medium. Methods: We present the average pulse profiles of 100 pulsars observed in the two LOFAR frequency bands: high band (120–167 MHz, 100 profiles) and low band (15–62 MHz, 26 profiles). We compare them with Westerbork Synthesis Radio Telescope (WSRT) and Lovell Telescope observations at higher frequencies (350 and 1400 MHz) to study the profile evolution. The profiles were aligned in absolute phase by folding with a new set of timing solutions from the Lovell Telescope, which we present along with precise dispersion measures obtained with LOFAR. Results: We find that the profile evolution with decreasing radio frequency does not follow a specific trend; depending on the geometry of the pulsar, new components can enter into or be hidden from view. Nonetheless, in general our observations confirm the widening of pulsar profiles at low frequencies, as expected from radius-to-frequency mapping or birefringence theories.
    Original languageUndefined
    Pages (from-to)1-34
    Number of pages34
    JournalAstronomy & astrophysics
    Volume586
    Issue numberA&A A92
    DOIs
    Publication statusPublished - 29 Jan 2016

    Keywords

    • EWI-27451
    • IR-103184
    • METIS-321663

    Cite this

    Pilla, M., Stappers, B. W., Falcke, H., Avruch, I. M., Bell, E., Gunst, A. W., & Bentum, M. J. (2016). Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR. Astronomy & astrophysics, 586(A&A A92), 1-34. https://doi.org/10.1051/0004-6361/201425196