102 research outputs found
All-sky Radio SETI
Over the last decade, Aperture Arrays (AA) have successfully replaced
parabolic dishes as the technology of choice at low radio frequencies - good
examples are the MWA, LWA and LOFAR. Aperture Array based telescopes present
several advantages, including sensitivity to the sky over a very wide
field-of-view. As digital and data processing systems continue to advance, an
all-sky capability is set to emerge, even at GHz frequencies. We argue that
assuming SETI events are both rare and transitory in nature, an instrument with
a large field-of-view, operating around the so-called water-hole (1-2 GHz),
might offer several advantages over contemporary searches. Sir Arthur C. Clarke
was the first to recognise the potential importance of an all-sky radio SETI
capability, as presented in his book, Imperial Earth. As part of the global SKA
(Square Kilometre Array) project, a Mid-Frequency Aperture Array (MFAA)
prototype known as MANTIS (Mid- Frequency Aperture Array Transient and
Intensity-Mapping System) is now being considered as a precursor for SKA-2.
MANTIS can be seen as a first step towards an all-sky radio SETI capability at
GHz frequencies. This development has the potential to transform the field of
SETI research, in addition to several other scientific programmes.Comment: 7 pages, 4 figures, accepted for publication, Proceedings of Science,
workshop on "MeerKAT Science: On the Pathway to the SKA", held in
Stellenbosch 25-27 May 2016. Comments welcom
Fast Radio Burst 121102 Pulse Detection and Periodicity: A Machine Learning Approach
We report the detection of 72 new pulses from the repeating fast radio burst
FRB 121102 in Breakthrough Listen C-band (4-8 GHz) observations at the Green
Bank Telescope. The new pulses were found with a convolutional neural network
in data taken on August 26, 2017, where 21 bursts have been previously
detected. Our technique combines neural network detection with dedispersion
verification. For the current application we demonstrate its advantage over a
traditional brute-force dedis- persion algorithm in terms of higher
sensitivity, lower false positive rates, and faster computational speed.
Together with the 21 previously reported pulses, this observa- tion marks the
highest number of FRB 121102 pulses from a single observation, total- ing 93
pulses in five hours, including 45 pulses within the first 30 minutes. The
number of data points reveal trends in pulse fluence, pulse detection rate, and
pulse frequency structure. We introduce a new periodicity search technique,
based on the Rayleigh test, to analyze the time of arrivals, with which we
exclude with 99% confidence pe- riodicity in time of arrivals with periods
larger than 5.1 times the model-dependent time-stamp uncertainty. In
particular, we rule out constant periods >10 ms in the barycentric arrival
times, though intrinsic periodicity in the time of emission remains plausible.Comment: 32 pages, 10 figure
A 1.1 to 1.9 GHz SETI Survey of the Kepler Field: I. A Search for Narrow-band Emission from Select Targets
We present a targeted search for narrow-band (< 5 Hz) drifting sinusoidal
radio emission from 86 stars in the Kepler field hosting confirmed or candidate
exoplanets. Radio emission less than 5 Hz in spectral extent is currently known
to only arise from artificial sources. The stars searched were chosen based on
the properties of their putative exoplanets, including stars hosting candidates
with 380 K > T_eq > 230 K, stars with 5 or more detected candidates or stars
with a super-Earth (R_p 50 day orbit. Baseband voltage data
across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C.
Byrd Green Bank Telescope between Feb--Apr 2011 and subsequently searched
offline. No signals of extraterrestrial origin were found. We estimate that
fewer than ~1% of transiting exoplanet systems host technological civilizations
that are radio loud in narrow-band emission between 1-2 GHz at an equivalent
isotropically radiated power (EIRP) of ~1.5 x 10^21 erg s^-1, approximately
eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the the
number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the
Milky Way to be < 10^-6 M_solar^-1. Here we describe our observations, data
reduction procedures and results.Comment: Accepted to the Astrophysical Journa
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