778 research outputs found
A sample of low energy bursts from FRB 121102
We present 41 bursts from the first repeating fast radio burst discovered
(FRB 121102). A deep search has allowed us to probe unprecedentedly low burst
energies during two consecutive observations (separated by one day) using the
Arecibo telescope at 1.4 GHz. The bursts are generally detected in less than a
third of the 580-MHz observing bandwidth, demonstrating that narrow-band FRB
signals may be more common than previously thought. We show that the bursts are
likely faint versions of previously reported multi-component bursts. There is a
striking lack of bursts detected below 1.35 GHz and simultaneous VLA
observations at 3 GHz did not detect any of the 41 bursts, but did detect one
that was not seen with Arecibo, suggesting preferred radio emission frequencies
that vary with epoch. A power law approximation of the cumulative distribution
of burst energies yields an index that is much steeper than the
previously reported value of . The discrepancy may be evidence for a
more complex energy distribution. We place constraints on the possibility that
the associated persistent radio source is generated by the emission of many
faint bursts ( ms). We do not see a connection between burst
fluence and wait time. The distribution of wait times follows a log-normal
distribution centered around s; however, some bursts have wait times
below 1 s and as short as 26 ms, which is consistent with previous reports of a
bimodal distribution. We caution against exclusively integrating over the full
observing band during FRB searches, because this can lower signal-to-noise.Comment: Accepted version. 16 pages, 7 figures, 1 tabl
Chorismate Mutase and 3-Deoxy-D-arabino-Heptulosonate 7-Phosphate Synthase of the Methylotrophic Actinomycete Amycolatopsis methanolica
Pulsar Wind Nebulae in EGRET Error Boxes
A remarkable number of pulsar wind nebulae (PWN) are coincident with EGRET
gamma-ray sources. X-ray and radio imaging studies of unidentified EGRET
sources have resulted in the discovery of at least 6 new pulsar wind nebulae
(PWN). Stationary PWN (SPWN) appear to be associated with steady EGRET sources
with hard spectra, typical for gamma-ray pulsars. Their toroidal morphologies
can help determine the geometry of the pulsar which is useful for constraining
models of pulsed gamma-ray emission. Rapidly moving PWN (RPWN) with more
cometary morphologies seem to be associated with variable EGRET sources in
regions where the ambient medium is dense compared to what is typical for the
ISM.Comment: 8 pages, 5 figures, to appear in the proceedings of "The
Multiwavelength Approach to Unidentified Sources", ed. G. Romero & K.S. Chen
From spin noise to systematics:stochastic processes in the first International Pulsar Timing Array data release
Twenty-One Millisecond Pulsars in Terzan 5 Using the Green Bank Telescope
We have discovered 21 millisecond pulsars (MSPs) in the globular cluster
Terzan 5 using the Green Bank Telescope, bringing the total of known MSPs in
Terzan 5 to 24. These discoveries confirm fundamental predictions of globular
cluster and binary system evolution. Thirteen of the new MSPs are in binaries,
of which two show eclipses and two have highly eccentric orbits. The
relativistic periastron advance for the two eccentric systems indicates that at
least one of these pulsars has a mass >1.68 Msun at 95% confidence. Such large
neutron star masses constrain the equation of state of matter at or beyond the
nuclear equilibrium density.Comment: 12 pages, 2 figures. Accepted by Science. Published electronically
via Science Express 13 Jan 200
From spin noise to systematics:stochastic processes in the first International Pulsar Timing Array data release
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