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

M. Pilia (1) , J.W.T. J Hessels (1) , B.W W Stappers (2) , V.I. Kondratiev (1) , M M Kramer (3) , J J van Leeuwen (4) , P P Weltevrede (2) , A G Lyne (2) , K Zagkouris (5) , T.E. E Hassall (6) , A.V. A Bilous (7) , R.P. P Breton (6) , H Falcke (1) , Jean-Mathias Griessmeier (8, 9) , E E Keane (10) , A A Karastergiou (11) , M M Kuniyoshi (12) , A A Noutsos (12) , S. Osłowski (13) , M. M Serylak (14) , C. C Sobey (1) , S V ter Veen (1) , A A Alexov (15) , A J Anderson (16) , A A Asgekar (1) , A A Avruch (17) , M E Bell (18) , M J Bentum (1) , G G Bernardi (19) , L. Bîrzan (20) , A A Bonafede (21) , B Breitling (22) , J J Broderick (5) , M M Brüggen (23) , C C Ciardi (24) , Stéphane C Corbel (25, 9) , D D de Geus (1) , A J de Jong (26) , A D Deller (1) , S D Duscha (1) , J J Eislöffel (27) , R A Fallows (28) , R Fender (29) , C C Ferrari (30) , W W Frieswijk (1) , M.A G Garrett (1) , A G Gunst (1) , J.P. J Hamaker (1) , H G Heald (1) , A A Horneffer (12) , P J Jonker (17) , J J Juette (31) , G G Kuper (1) , P P Maat (1) , M G Mann (32) , S M Markoff (4) , R M Mcfadden (1) , D. D Mckay-Bukowski (33) , C J Miller-Jones (34) , A A Nelles (35) , H. P Paas (36) , M P Pandey-Pommier (37) , M. P Pietka (5) , P P Pizzo (1) , P G Polatidis (37) , R W Reich (12) , R Röttgering (20) , A. A Rowlinson (38) , S D Schwarz (39) , O Smirnov (40) , S M Steinmetz (41) , S A Stewart (42) , S J Swinbank (43) , Michel Tagger (8) , Y Tang (44) , C C Tasse (45) , S Thoudam (46) , C C Toribio (1) , A J van Der Horst (4) , R V Vermeulen (1) , C C Vocks (32) , R J van Weeren (17) , R.A.M.J Wijers (47) , R W Wijnands (4) , S J Wijnholds (1) , O W Wucknitz (48) , P P Zarka (45)

1 ASTRON - Netherlands Institute for Radio Astronomy
2 Jodrell Bank Centre for Astrophysics
3 VUMC - Vrije Universiteit Medical Centre
4 AI PANNEKOEK - Astronomical Institute Anton Pannekoek
5 Oxford Astrophysics
6 School of Physics and Astronomy [Southampton]
7 IMAPP - Institute for Mathematics, Astrophysics and Particle Physics
8 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
9 USN - Unité Scientifique de la Station de Nançay
10 CAS - Centre for Astrophysics and Supercomputing [Swinburne]
11 Department of Physics [Oxford]
12 MPIFR - Max-Planck-Institut für Radioastronomie
13 Universität Bielefeld = Bielefeld University
14 University of Cape Town
15 STSci - Space Telescope Science Institute
16 Epidémiologie et Biostatistique [Bordeaux]
17 SRON - SRON Netherlands Institute for Space Research
18 University of Southampton
19 CfA - Harvard-Smithsonian Center for Astrophysics
20 Leiden Observatory [Leiden]
21 University of Hamburg
22 DSMZ - Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures
23 University of Edinburgh
24 MPA - Max-Planck-Institut für Astrophysik
25 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
26 Structural Dynamics and Acoustics
27 TLS - Thüringer Landessternwarte Tautenburg
28 Institute of Mathematical and Physical Sciences
29 Department of Astrophysics [Oxford]
30 Département de Géologie
31 Astronomisches Institut der Ruhr-Universität Bochum
32 AIP - Leibniz-Institut für Astrophysik Potsdam
33 Department of Physical Sciences, University of Oulu
34 Curtin University [Perth]
35 Radboud University [Nijmegen]
36 University of Groningen [Groningen]
37 CRAL - Centre de Recherche Astrophysique de Lyon
38 ATNF - Australia Telescope National Facility
39 ING - Institute of Farm Animal Genetics
40 SKA South Africa
41 AIP - Astrophysikalisches Institut Potsdam
42 Department of Physics [Dunedin]
43 Princeton University
44 Edinburgh Research Station
45 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
46 Department of Astrophysics [Nijmegen]
47 Anton Pannekoek Institute for Astronomy
48 AlfA - Argelander-Institut für Astronomie

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.

Keywords: stars: neutron; pulsars: general

Domains: Sciences of the Universe [physics]

M. Pilia, J.W.T. J Hessels, B.W W Stappers, V.I. Kondratiev, M M Kramer, et al.. Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR. Astronomy and Astrophysics - A&A, 2016, 586 (A92), 34 p. ⟨10.1051/0004-6361/201425196⟩. ⟨insu-01467174⟩