58 research outputs found
Observations Of Rotating Radio Transients With The First Station Of The Long Wavelength Array
Rotating Radio Transients (RRATs) are a subclass of pulsars first identified in 2006 that are detected only in searches for single pulses and not through their time averaged emission. Here, we present the results of observations of 19 RRATs using the first station of the Long Wavelength Array (LWA1) at frequencies between 30 MHz and 88 MHz. The RRATs observed here were first detected in higher frequency pulsar surveys. Of the 19 RRATs observed, 2 sources were detected and their dispersion measures, periods, pulse profiles, and flux densities are reported and compared to previous higher frequency measurements. We find a low detection rate (11%), which could be a combination of the lower sensitivity of LWA1 compared to the higher frequency telescopes, and the result of scattering by the interstellar medium or a spectral turnover. Taylor, G B; Stovall, K; McCrackan, M; McLaughlin, M A; Miller, R; Karako-Argaman, C; Dowell, J; Schinzel, F
Observations Of Rotating Radio Transients With The First Station Of The Long Wavelength Array
Rotating Radio Transients (RRATs) are a subclass of pulsars first identified in 2006 that are detected only in searches for single pulses and not through their time averaged emission. Here, we present the results of observations of 19 RRATs using the first station of the Long Wavelength Array (LWA1) at frequencies between 30 MHz and 88 MHz. The RRATs observed here were first detected in higher frequency pulsar surveys. Of the 19 RRATs observed, 2 sources were detected and their dispersion measures, periods, pulse profiles, and flux densities are reported and compared to previous higher frequency measurements. We find a low detection rate (11%), which could be a combination of the lower sensitivity of LWA1 compared to the higher frequency telescopes, and the result of scattering by the interstellar medium or a spectral turnover. Taylor, G B; Stovall, K; McCrackan, M; McLaughlin, M A; Miller, R; Karako-Argaman, C; Dowell, J; Schinzel, F
Discovery and Follow-up of Rotating Radio Transients with the Green Bank and LOFAR Telescopes
We have discovered 21 Rotating Radio Transients (RRATs) in data from the
Green Bank Telescope (GBT) 350-MHz Drift-scan and the Green Bank North
Celestial Cap pulsar surveys using a new candidate sifting algorithm. RRATs are
pulsars with sporadic emission that are detected through their bright single
pulses rather than Fourier domain searches. We have developed {\tt RRATtrap}, a
single-pulse sifting algorithm that can be integrated into pulsar survey data
analysis pipelines in order to find RRATs and Fast Radio Bursts. We have
conducted follow-up observations of our newly discovered sources at several
radio frequencies using the GBT and Low Frequency Array (LOFAR), yielding
improved positions and measurements of their periods, dispersion measures, and
burst rates, as well as phase-coherent timing solutions for four of them. The
new RRATs have dispersion measures (DMs) ranging from 15 to 97 pc cm,
periods of 240 ms to 3.4 s, and estimated burst rates of 20 to 400 pulses
hr at 350 MHz. We use this new sample of RRATs to perform statistical
comparisons between RRATs and canonical pulsars in order to shed light on the
relationship between the two populations. We find that the DM and spatial
distributions of the RRATs agree with those of the pulsars found in the same
survey. We find evidence that slower pulsars (i.e. ms) are
preferentially more likely to emit bright single pulses than are faster pulsars
( ms), although this conclusion is tentative. Our results are consistent
with the proposed link between RRATs, transient pulsars, and canonical pulsars
as sources in various parts of the pulse activity spectrum.Comment: 18 pages, 13 figures, 5 tables, published in Ap
A millisecond pulsar in a stellar triple system
Gravitationally bound three-body systems have been studied for hundreds of
years and are common in our Galaxy. They show complex orbital interactions,
which can constrain the compositions, masses, and interior structures of the
bodies and test theories of gravity, if sufficiently precise measurements are
available. A triple system containing a radio pulsar could provide such
measurements, but the only previously known such system, B1620-26 (with a
millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of
several decades), shows only weak interactions. Here we report precision timing
and multi-wavelength observations of PSR J0337+1715, a millisecond pulsar in a
hierarchical triple system with two other stars. Strong gravitational
interactions are apparent and provide the masses of the pulsar (1.4378(13)
Msun, where Msun is the solar mass and the parentheses contain the uncertainty
in the final decimal places) and the two white dwarf companions (0.19751(15)
Msun and 0.4101(3) Msun), as well as the inclinations of the orbits (both
approximately 39.2 degrees). The unexpectedly coplanar and nearly circular
orbits indicate a complex and exotic evolutionary past that differs from those
of known stellar systems. The gravitational field of the outer white dwarf
strongly accelerates the inner binary containing the neutron star, and the
system will thus provide an ideal laboratory in which to test the strong
equivalence principle of general relativity.Comment: 17 pages, 3 figures, 1 table. Published online by Nature on 5 Jan
2014. Extremely minor differences with published version may exis
Fast Radio Burst Discovered in the Arecibo Pulsar ALFA Survey
Recent work has exploited pulsar survey data to identify temporally isolated,
millisecond-duration radio bursts with large dispersion measures (DMs). These
bursts have been interpreted as arising from a population of extragalactic
sources, in which case they would provide unprecedented opportunities for
probing the intergalactic medium; they may also be linked to new source
classes. Until now, however, all so-called fast radio bursts (FRBs) have been
detected with the Parkes radio telescope and its 13-beam receiver, casting some
concern about the astrophysical nature of these signals. Here we present FRB
121102, the first FRB discovery from a geographic location other than Parkes.
FRB 121102 was found in the Galactic anti-center region in the 1.4-GHz Pulsar
ALFA survey with the Arecibo Observatory with a DM = 557.4 3 pc
cm, pulse width of ms, and no evidence of interstellar
scattering. The observed delay of the signal arrival time with frequency agrees
precisely with the expectation of dispersion through an ionized medium. Despite
its low Galactic latitude (), the burst has three times the
maximum Galactic DM expected along this particular line-of-sight, suggesting an
extragalactic origin. A peculiar aspect of the signal is an inverted spectrum;
we interpret this as a consequence of being detected in a sidelobe of the ALFA
receiver. FRB 121102's brightness, duration, and the inferred event rate are
all consistent with the properties of the previously detected Parkes bursts.Comment: 9 pages, 3 figures, submitted to Ap
The Green Bank Northern Celestial Cap Pulsar Survey - I: Survey Description, Data Analysis, and Initial Results
We describe an ongoing search for pulsars and dispersed pulses of radio
emission, such as those from rotating radio transients (RRATs) and fast radio
bursts (FRBs), at 350 MHz using the Green Bank Telescope. With the Green Bank
Ultimate Pulsar Processing Instrument, we record 100 MHz of bandwidth divided
into 4,096 channels every 81.92 . This survey will cover the entire sky
visible to the Green Bank Telescope (, or 82% of the sky)
and outside of the Galactic Plane will be sensitive enough to detect slow
pulsars and low dispersion measure (30 ) millisecond
pulsars (MSPs) with a 0.08 duty cycle down to 1.1 mJy. For pulsars with a
spectral index of 1.6, we will be 2.5 times more sensitive than previous and
ongoing surveys over much of our survey region. Here we describe the survey,
the data analysis pipeline, initial discovery parameters for 62 pulsars, and
timing solutions for 5 new pulsars. PSR J02145222 is an MSP in a long-period
(512 days) orbit and has an optical counterpart identified in archival data.
PSR J06365129 is an MSP in a very short-period (96 minutes) orbit with a
very low mass companion (8 ). PSR J06455158 is an isolated MSP
with a timing residual RMS of 500 ns and has been added to pulsar timing array
experiments. PSR J14347257 is an isolated, intermediate-period pulsar that
has been partially recycled. PSR J18164510 is an eclipsing MSP in a
short-period orbit (8.7 hours) and may have recently completed its spin-up
phase.Comment: 18 pages, 10 figures, 5 tables, accepted by Ap
A Search for Fast Radio Bursts with the GBNCC Pulsar Survey
We report on a search for Fast Radio Bursts (FRBs) with the Green Bank
Northern Celestial Cap (GBNCC) Pulsar Survey at 350 MHz. Pointings amounting to
a total on-sky time of 61 days were searched to a DM of 3000 pc cm while
the rest (23 days; 29% of the total time) were searched to a DM of 500 pc
cm. No FRBs were detected in the pointings observed through May 2016. We
estimate a 95% confidence upper limit on the FRB rate of FRBs
sky day above a peak flux density of 0.63 Jy at 350 MHz for an
intrinsic pulse width of 5 ms. We place constraints on the spectral index
by running simulations for different astrophysical scenarios and
cumulative flux density distributions. The non-detection with GBNCC is
consistent with the 1.4-GHz rate reported for the Parkes surveys for in the absence of scattering and free-free absorption and in the presence of scattering, for a Euclidean flux distribution. The
constraints imply that FRBs exhibit either a flat spectrum or a spectral
turnover at frequencies above 400 MHz. These constraints also allow estimation
of the number of bursts that can be detected with current and upcoming surveys.
We predict that CHIME may detect anywhere from several to 50 FRBs a day
(depending on model assumptions), making it well suited for interesting
constraints on spectral index, the log -log slope and pulse profile
evolution across its bandwidth (400-800 MHz).Comment: 18 pages, 10 figures, Accepted for publication in Ap
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