First Light for the First Station of the Long Wavelength Array

Taylor, G. B.; Ellingson, S.W.; Kassim, N. E.; Craig, John L.; Dowell, Jayce; Wolfe, Christopher; Hartman, J. M.; Bernardi, G.; Clarke, T. E.; Cohen, A. S.; Dalal, N. P.; Erickson, W. C.; Hicks, B. C.; Greenhill, L. J.; Jacoby, B. A.; Lane, W. M.; Lazio, Joseph; Mitchell, D. A.; Navarro, Robert; Ord, S. M.; Pihlström, Y. M.; Polisensky, Emil; Ray, Paul S.; Rickard, L. J.; Schinzel, F. K.; Schmitt, H. R.; Sigman, E.; Soriano, Melissa; Stewart, K. P.; Stovall, K.; Tremblay, S. E.; Wang, D.; Weiler, K. W.; White, S. M.; Wood, D. L.

doi:10.1142/s2251171712500043

Cited by 158 publications

(136 citation statements)

References 44 publications

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“…The Long Wavelength Array (LWA) data were taken using the first station of the LWA (LWA1; Taylor et al (2012); Ellingson et al (2013)), which consists of 256 dipole antennas sensitive to radio waves in the 10-88 MHz range. LWA1 is co-located with the Very Large Array in New Mexico, USA.…”

Section: Long Wavelength Arraymentioning

confidence: 99%

A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10

Mereghetti

Kuiper

Tiengo

et al. 2016

ApJ

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We report on simultaneous X-ray and radio observations of the mode-switching pulsar PSR B0943+10 obtained with the XMM-Newton satellite and the LOFAR, LWA and Arecibo radio telescopes in November 2014. We confirm the synchronous X-ray/radio switching between a radio-bright (B) and a radio-quiet (Q) mode, in which the X-ray flux is a factor ∼ 2.4 higher than in the B-mode. We discovered X-ray pulsations, with pulsed fraction of 38±5% (0.5-2 keV), during the B-mode, and confirm their presence in Q-mode, where the pulsed fraction increases with energy from ∼20% up to ∼65% at 2 keV. We found marginal evidence for an increase in the X-ray pulsed fraction during B-mode on a timescale of hours. The Q-mode X-ray spectrum requires a fit with a two-component model (either a power-law plus blackbody or the sum of two blackbodies), while the B-mode spectrum is well fit by a single blackbody (a single power-law is rejected). With a maximum likelihood analysis, we found that in Q-mode the pulsed emission has a thermal blackbody spectrum with temperature ∼ 3.4 × 10 6 K and the unpulsed emission is a power-law with photon index ∼2.5, while during B-mode both the pulsed and unpulsed emission can be fit by either a blackbody or a power law with similar values of temperature and photon index. A Chandra image shows no evidence for diffuse X-ray emission. These results support a scenario in which both unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap (∼1500 m 2 ) with a strong non-dipolar magnetic field (∼ 10 14 G), are present during both radio modes and vary in intensity in a correlated way. This is broadly consistent with the predictions of the partially screened gap model and does not necessarily imply global magnetospheric rearrangements to explain the mode switching.

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Section: Long Wavelength Arraymentioning

confidence: 99%

A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10

Mereghetti

Kuiper

Tiengo

et al. 2016

ApJ

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“…These include a relatively wide-band (16 MHz) beam-forming mode and two transient buffer (TB) modes that each capture the signals from individual antennas, allowing for all-sky imaging after the fact. For more details of the LWA1 radio telescope, see Hicks et al (2012), Taylor et al (2012), and Ellingson et al (2013).…”

Section: Lwa1 Wwv Fais and Meteor Trailsmentioning

confidence: 99%

A multi-platform investigation of midlatitude sporadic E and its ties to E–F coupling and meteor activity

Helmboldt

2016

Ann. Geophys.

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Abstract. This paper describes the results of a multiplatform observing campaign aimed at studying midlatitude sporadic E (E s ) and associated ionospheric phenomena. The assets used were the digisonde in Boulder, Colorado; the first station of the Long Wavelength Array, LWA1, in New Mexico; the transmitters of the radio station WWV in Colorado; and 61 continuously operating GPS receivers between LWA1 and WWV. The results show that southwestward-directed medium-scale traveling ionospheric disturbances (MSTIDs) were substantially more prevalent when E s was detected. The amplitudes of these correlate with a plasma frequency up to about 4.5 MHz. For f p 5 MHz, the MSTIDs become significantly weaker and basically vanish above ∼ 6.5 MHz. The prevalence of meteor trail reflections observed with LWA1 also correlates with f p up to about 4.5 MHz; above this limit, the relationship exhibits a significant turnover. The observed intensity of coherent backscatter from E s field-aligned irregularities (FAIs) also correlates with inferred plasma frequency. However, this trend continues to higher frequencies with a peak near 6 MHz, followed by a much more subtle turnover. The reflected power from E s structures observed with LWA1 is significantly more correlated on spatial scales between 10 and 40 km. The magnitude of this correlation increases with f p up to ∼ 6 MHz, above which it drops. These results are consistent with the following: (1) southwestwarddirected MSTIDs are produced via E-F coupling; (2) this coupling is stronger when the E s layer, seeded by meteor ablation, is more dense; (3) the coupling is substantially diminished for E s layers harboring extremely dense structures (f p 5 MHz).

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“…Taylor et al 2012). As of 2015, only three other MSPs were detected in an initial census (Stovall et al 2015), so J1400−1431 is one of very few MSPs detected at these low frequencies.…”

Section: Flux Density Estimates and Scintillationmentioning

confidence: 96%

A Multiwavelength Study of Nearby Millisecond Pulsar PSR J1400−1431: Improved Astrometry and an Optical Detection of Its Cool White Dwarf Companion

Swiggum

Kaplan

McLaughlin

et al. 2017

ApJ

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In 2012, five high school students involved in the Pulsar Search Collaboratory discovered the millisecond pulsar PSR J1400−1431 and initial timing parameters were published in Rosen et al. (2013) a year later. Since then, we have obtained a phase-connected timing solution spanning five years, resolving a significant position discrepancy and measuringṖ , proper motion, parallax, and a monotonic slope in dispersion measure over time. Due to PSR J1400−1431's proximity and significant proper motion, we use the Shklovskii effect and other priors to determine a 95% confidence interval for PSR J1400−1431's distance, d = 270 +130 −80 pc. With an improved timing position, we present the first detection of the pulsar's low-mass white dwarf (WD) companion using the Goodman Spectrograph on the 4.1-m SOAR telescope. Deeper imaging suggests that it is a cool DA-type WD with T eff = 3000 ± 100 K and R/R = (2.19 ± 0.03) × 10 −2 (d/270 pc). We show a convincing association between PSR J1400−1431 and a γ-ray point source, 3FGL J1400.5−1437, but only weak (3.3-σ) evidence of pulsations after folding γ-ray photons using our radio timing model. We detect an X-ray counterpart with XMMNewton but the measured X-ray luminosity (1 × 10 29 ergs s −1 ) makes PSR J1400−1431 the least X-ray luminous rotation-powered millisecond pulsar (MSP) detected to date. Together, our findings present a consistent picture of a nearby (d ≈ 230 pc) MSP in a 9.5 day orbit around a cool, ∼0.3 M WD companion, with orbital inclination, i 60• .

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First Light for the First Station of the Long Wavelength Array

Cited by 158 publications

References 44 publications

A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10

A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10

A multi-platform investigation of midlatitude sporadic <i>E</i> and its ties to <i>E</i>–<i>F</i> coupling and meteor activity

A Multiwavelength Study of Nearby Millisecond Pulsar PSR J1400−1431: Improved Astrometry and an Optical Detection of Its Cool White Dwarf Companion

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First Light for the First Station of the Long Wavelength Array

Cited by 158 publications

References 44 publications

A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10

A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10

A multi-platform investigation of midlatitude sporadic &lt;i&gt;E&lt;/i&gt; and its ties to &lt;i&gt;E&lt;/i&gt;–&lt;i&gt;F&lt;/i&gt; coupling and meteor activity

A Multiwavelength Study of Nearby Millisecond Pulsar PSR J1400−1431: Improved Astrometry and an Optical Detection of Its Cool White Dwarf Companion

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A multi-platform investigation of midlatitude sporadic <i>E</i> and its ties to <i>E</i>–<i>F</i> coupling and meteor activity