skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: PULSAR OBSERVATIONS USING THE FIRST STATION OF THE LONG WAVELENGTH ARRAY AND THE LWA PULSAR DATA ARCHIVE

Abstract

We present initial pulsar results from the first station of the Long Wavelength Array (LWA1) obtained during the commissioning period of LWA1 and in early science results. We present detections of periodic emission from 44 previously known pulsars, including 3 millisecond pulsars. The effects of the interstellar medium (ISM) on pulsar emission are significantly enhanced at the low frequencies of the LWA1 band (10–88 MHz), making LWA1 a very sensitive instrument for characterizing changes in the dispersion measure (DM) and other effects from the ISM. Pulsars also often have significant evolution in their pulse profile at low frequency and a break in their spectral index. We report DM measurements for 44 pulsars, mean flux density measurements for 36 pulsars, and multi-frequency component spacing and widths for 15 pulsars with more than one profile component. For 27 pulsars, we report spectral index measurements within our frequency range. We also introduce the LWA1 Pulsar Data Archive, which stores reduced data products from LWA1 pulsar observations. Reduced data products for the observations presented here can be found in the archive. Reduced data products from future LWA1 pulsar observations will also be made available through the archive.

Authors:
; ; ; ; ;  [1]; ;  [2];  [3];  [4]
  1. Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM (United States)
  2. Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)
  3. Center for Advanced Radio Astronomy, University of Texas at Brownsville, One West University Boulevard, Brownsville, TX 78520 (United States)
  4. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91106 (United States)
Publication Date:
OSTI Identifier:
22525667
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 808; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DETECTION; EMISSION; FLUX DENSITY; INDEXES; INTERSTELLAR SPACE; MHZ RANGE; PERIODICITY; PULSARS; PULSES; STAR EVOLUTION; WAVELENGTHS

Citation Formats

Stovall, K., Dowell, J., Eftekhari, T., McCrackan, M., Schinzel, F. K., Taylor, G. B., Ray, P. S., Blythe, J., Garcia, A., and Lazio, T. J. W., E-mail: stovall.kevin@gmail.com. PULSAR OBSERVATIONS USING THE FIRST STATION OF THE LONG WAVELENGTH ARRAY AND THE LWA PULSAR DATA ARCHIVE. United States: N. p., 2015. Web. doi:10.1088/0004-637X/808/2/156.
Stovall, K., Dowell, J., Eftekhari, T., McCrackan, M., Schinzel, F. K., Taylor, G. B., Ray, P. S., Blythe, J., Garcia, A., & Lazio, T. J. W., E-mail: stovall.kevin@gmail.com. PULSAR OBSERVATIONS USING THE FIRST STATION OF THE LONG WAVELENGTH ARRAY AND THE LWA PULSAR DATA ARCHIVE. United States. doi:10.1088/0004-637X/808/2/156.
Stovall, K., Dowell, J., Eftekhari, T., McCrackan, M., Schinzel, F. K., Taylor, G. B., Ray, P. S., Blythe, J., Garcia, A., and Lazio, T. J. W., E-mail: stovall.kevin@gmail.com. 2015. "PULSAR OBSERVATIONS USING THE FIRST STATION OF THE LONG WAVELENGTH ARRAY AND THE LWA PULSAR DATA ARCHIVE". United States. doi:10.1088/0004-637X/808/2/156.
@article{osti_22525667,
title = {PULSAR OBSERVATIONS USING THE FIRST STATION OF THE LONG WAVELENGTH ARRAY AND THE LWA PULSAR DATA ARCHIVE},
author = {Stovall, K. and Dowell, J. and Eftekhari, T. and McCrackan, M. and Schinzel, F. K. and Taylor, G. B. and Ray, P. S. and Blythe, J. and Garcia, A. and Lazio, T. J. W., E-mail: stovall.kevin@gmail.com},
abstractNote = {We present initial pulsar results from the first station of the Long Wavelength Array (LWA1) obtained during the commissioning period of LWA1 and in early science results. We present detections of periodic emission from 44 previously known pulsars, including 3 millisecond pulsars. The effects of the interstellar medium (ISM) on pulsar emission are significantly enhanced at the low frequencies of the LWA1 band (10–88 MHz), making LWA1 a very sensitive instrument for characterizing changes in the dispersion measure (DM) and other effects from the ISM. Pulsars also often have significant evolution in their pulse profile at low frequency and a break in their spectral index. We report DM measurements for 44 pulsars, mean flux density measurements for 36 pulsars, and multi-frequency component spacing and widths for 15 pulsars with more than one profile component. For 27 pulsars, we report spectral index measurements within our frequency range. We also introduce the LWA1 Pulsar Data Archive, which stores reduced data products from LWA1 pulsar observations. Reduced data products for the observations presented here can be found in the archive. Reduced data products from future LWA1 pulsar observations will also be made available through the archive.},
doi = {10.1088/0004-637X/808/2/156},
journal = {Astrophysical Journal},
number = 2,
volume = 808,
place = {United States},
year = 2015,
month = 8
}
  • We present multi-wavelength observations of the unassociated γ-ray source 3FGL J2039.6−5618 detected by the Fermi Large Area Telescope. The source γ-ray properties suggest that it is a pulsar, most likely a millisecond pulsar, for which neither radio nor γ-ray pulsations have been detected. We observed 3FGL J2039.6−5618 with XMM-Newton and discovered several candidate X-ray counterparts within/close to the γ-ray error box. The brightest of these X-ray sources is variable with a period of 0.2245 ± 0.0081 days. Its X-ray spectrum can be described by a power law with photon index Γ{sub X} = 1.36 ± 0.09, and hydrogen column density N{sub H} < 4 × 10{sup 20} cm{sup −2}, whichmore » gives an unabsorbed 0.3–10 keV X-ray flux of 1.02 × 10{sup −13} erg cm{sup −2} s{sup −1}. Observations with the Gamma-Ray Burst Optical/Near-Infrared Detector discovered an optical counterpart to this X-ray source, with a time-averaged magnitude g′ ∼ 19.5. The counterpart features a flux modulation with a period of 0.22748 ± 0.00043 days that coincides, within the errors, with that of the X-ray source, confirming the association based on the positional coincidence. We interpret the observed X-ray/optical periodicity as the orbital period of a close binary system where one of the two members is a neutron star. The light curve profile of the companion star, which has two asymmetric peaks, suggests that the optical emission comes from two regions with different temperatures on its tidally distorted surface. Based upon its X-ray and optical properties, we consider this source as the most likely X-ray counterpart to 3FGL J2039.6−5618, which we propose to be a new redback system.« less
  • Understanding star formation in resolved low mass systems requires the integration of information obtained from observations at different wavelengths. We have combined new and archival multi-wavelength observations on a set of 20 nearby starburst and post-starburst dwarf galaxies to create a data archive of calibrated, homogeneously reduced images. Named the panchromatic “STARBurst IRregular Dwarf Survey” archive, the data are publicly accessible through the Mikulski Archive for Space Telescopes. This first release of the archive includes images from the Galaxy Evolution Explorer Telescope (GALEX), the Hubble Space Telescope (HST), and the Spitzer Space Telescope (Spitzer) Multiband Imaging Photometer instrument. The datamore » sets include flux calibrated, background subtracted images, that are registered to the same world coordinate system. Additionally, a set of images are available that are all cropped to match the HST field of view. The GALEX and Spitzer images are available with foreground and background contamination masked. Larger GALEX images extending to 4 times the optical extent of the galaxies are also available. Finally, HST images convolved with a 5″ point spread function and rebinned to the larger pixel scale of the GALEX and Spitzer 24 μm images are provided. Future additions are planned that will include data at other wavelengths such as Spitzer IRAC, ground-based Hα, Chandra X-ray, and Green Bank Telescope H i imaging.« less
  • Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems have been combined with lower precision single-aperture measurements covering a much longer timespan (from eyepiece measurements, speckle interferometry, and adaptive optics) to determine improved visual orbits for 20 binary stars. In some cases, radial velocity observations exist to constrain the full three-dimensional orbit and determine component masses. The visual orbit of one of these binaries-{alpha} Com (HD 114378)-shows that the system is likely to have eclipses, despite its very long period of 26 years. The next eclipse is predicted to be within a week of 2015 January 24.
  • Very large Array (VLA) synthesis maps of the active regions AR 2505 and AR 2646 at wavelengths of 2 cm, 6 cm, and 20 cm are presented and compared with the magnetic structure of the underlying photosphere.
  • The observation of massive black hole binaries with pulsar timing arrays (PTAs) is one of the goals of gravitational-wave astronomy in the coming years. Massive (> or approx. 10{sup 8}M{sub {center_dot}}) and low-redshift (< or approx. 1.5) sources are expected to be individually resolved by upcoming PTAs, and our ability to use them as astrophysical probes will depend on the accuracy with which their parameters can be measured. In this paper we estimate the precision of such measurements using the Fisher-information-matrix formalism. For this initial study we restrict ourselves to 'monochromatic' sources, i.e. binaries whose frequency evolution is negligible duringmore » the expected {approx_equal}10 yr observation time, which represent the bulk of the observable population based on current astrophysical predictions. In this approximation, the system is described by seven parameters and we determine their expected statistical errors as a function of the number of pulsars in the array, the array sky coverage, and the signal-to-noise ratio (SNR) of the signal. At fixed SNR (regardless of the number of pulsars in the PTA), the gravitational-wave astronomy capability of a PTA is achieved with {approx_equal}20 pulsars; adding more pulsars (up to 1000) to the array reduces the source error box in the sky {Delta}{Omega} by a factor {approx_equal}5 and has negligible consequences on the statistical errors on the other parameters, because the correlations among parameters are already removed to a large extent. If one folds in the increase of coherent SNR proportional to the square root of the number of pulsars, {Delta}{Omega} improves as 1/SNR{sup 2} and the other parameters as 1/SNR. For a fiducial PTA of 100 pulsars uniformly distributed in the sky and a coherent SNR=10, we find {Delta}{Omega}{approx_equal}40 deg{sup 2}, a fractional error on the signal amplitude of {approx_equal}30% (which constrains only very poorly the chirp mass-luminosity distance combination M{sup 5/3}/D{sub L}), and the source inclination and polarization angles are recovered at the {approx_equal}0.3 rad level. The ongoing Parkes PTA is particularly sensitive to systems located in the southern hemisphere, where at SNR=10 the source position can be determined with {Delta}{Omega}{approx_equal}10 deg{sup 2}, but has poorer (by an order of magnitude) performance for sources in the northern hemisphere.« less