Observations of Low-frequency Radio Emission from Millisecond Pulsars and Multipath Propagation in the Interstellar Medium
Artikel i vetenskaplig tidskrift, 2018

Studying the gravitational-wave sky with pulsar timing arrays (PTAs) is a key science goal for the Square Kilometre Array (SKA) and its pathfinder telescopes. With current PTAs reaching sub-microsecond timing precision, making accurate measurements of interstellar propagation effects and mitigating them effectively has become increasingly important to realize PTA goals. As these effects are much stronger at longer wavelengths, low-frequency observations are most appealing for characterizing the interstellar medium (ISM) along the sight lines toward PTA pulsars. The Murchison Widefield Array (MWA) and the Engineering Development Array (EDA), which utilizes MWA technologies, present promising opportunities for undertaking such studies, particularly for PTA pulsars located in the southern sky. Such pulsars are also the prime targets for PTA efforts planned with the South African MeerKAT, and eventually with the SKA. In this paper we report on observations of two bright southern millisecond pulsars, PSR J0437-4715 and PSR J2145-0750, made with these facilities; MWA observations sampled multiple frequencies across the 80-250 MHz frequency range, while the EDA provided direct-sampled baseband data to yield a large instantaneous usable bandwidth of similar to 200 MHz. Using these exploratory observations, we investigate various aspects relating to pulsar emission and ISM properties, such as spectral evolution of the mean pulse shape, scintillation as a function of frequency, chromaticity in interstellar dispersion, and flux density spectra at low frequencies. Systematic and regular monitoring observations will help ascertain the role of low-frequency measurements in PTA experiments, while simultaneously providing a detailed characterization of the ISM toward the pulsars, which will be useful in devising optimal observing strategies for future PTA experiments.

ISM: general

pulsars: individual (PSR J0437-4715, PSR J2145-0750)

methods: observational

pulsars: general

instrumentation: interferometers

Författare

N. D. R. Bhat

Curtin University

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

S. E. Tremblay

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

Curtin University

Franz Kirsten

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

B. W. Meyers

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

Curtin University

CSIRO Astronomy and Space Science

M. Sokolowski

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

Curtin University

W. van Straten

Auckland University of Technology

S. J. McSweeney

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

Curtin University

S. M. Ord

CSIRO Astronomy and Space Science

R. M. Shannon

Curtin University

CSIRO Astronomy and Space Science

ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav)

Swinburne University of Technology

A. Beardsley

Arizona State University

B. Crosse

Curtin University

D. Emrich

Curtin University

T. M. O. Franzen

Curtin University

L. Horsley

Curtin University

M. Johnston-Hollitt

Curtin University

D. L. Kaplan

University of Wisconsin Madison

D. Kenney

Curtin University

M. F. Morales

University of Washington

D. Pallot

University of Western Australia

K. Steele

Curtin University

S. J. Tingay

Curtin University

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

C. M. Trott

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

Curtin University

M. Walker

Curtin University

R. B. Wayth

Curtin University

ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

A. Williams

Curtin University

C. Wu

University of Western Australia

Astrophysical Journal, Supplement Series

0067-0049 (ISSN) 1538-4365 (eISSN)

Vol. 238 1 1

Ämneskategorier

Medicinsk laboratorie- och mätteknik

Astronomi, astrofysik och kosmologi

Fusion, plasma och rymdfysik

DOI

10.3847/1538-4365/aad37c

Mer information

Senast uppdaterat

2018-09-11