The Breakthrough Listen Search for Intelligent Life: A 3.95-8.00 GHz Search for Radio Technosignatures in the Restricted Earth Transit Zone

We report on a search for artificial narrowband signals of 20 stars within the restricted Earth Transit Zone as a part of the ten-year Breakthrough Listen (BL) search for extraterrestrial intelligence. The restricted Earth Transit Zone is the region of the sky from which an observer would see the Earth transit the Sun with an impact parameter of less than 0.5. This region of the sky is geometrically unique, providing a potential way for an extraterrestrial intelligence to discover the Solar System. The targets were nearby (7-143 pc) and the search covered an electromagnetic frequency range of 3.95-8.00 GHz. We used the Robert C. Byrd Green Bank Telescope to perform these observations with the standard BL data recorder. We searched these data for artificial narrowband ($\sim$Hz) signals with Doppler drift rates of $\pm 20$ Hz s$^{-1}$. We found one set of potential candidate signals on the target HIP 109656 which was then found to be consistent with known properties of anthropogenic radio frequency interference. We find no evidence for radio technosignatures from extraterrestrial intelligence in our observations. The observing campaign achieved a minimum detectable flux which would have allowed detections of emissions that were $10^{-3}$ to $0.88$ times as powerful as the signaling capability of the Arecibo radar transmitter, for the nearest and furthest stars respectively. We conclude that at least $8\%$ of the systems in the restricted Earth Transit Zone within 150 pc do not possess the type of transmitters searched in this survey. To our knowledge, this is the first targeted search for extraterrestrial intelligence of the restricted Earth Transit Zone. All data used in this paper are publicly available via the Breakthrough Listen Public Data Archive (http://seti.berkeley.edu/bldr2).Comment: 17 pages, 8 figures, submitted to Ap

Breakthrough Listen follow-up of the reported transient signal observed at the Arecibo Telescope in the direction of Ross 128

We undertook observations with the Green Bank Telescope, simultaneously with the 300 m telescope in Arecibo, as a follow-up of a possible flare of radio emission from Ross 128. We report here the non-detections from the GBT observations in C band (4–8 GHz), as well as non-detections in archival data at L band (1.1–1.9 GHz). We suggest that a likely scenario is that the emission comes from one or more satellites passing through the same region of the sky

TEC, Trigger and Check, preparing LOFAR for Lunar observations

One of the main ways to use radio to detect Ultra High Energy Neutrinos and Cosmic Rays is the Lunar Askaryan technique, that uses the Moon as a target and searches for nanosecond pulses with large radio telescopes. To use low frequency aperture arrays, such as LOFAR and the SKA, pose new challenges and possibilities in detection techniques of short radio pulses and to measure the Total Electron Content (TEC). As a prepatory work, we have used other measurements that use similar techniques, or that can answer a specific question, with the LOFAR radio telescope. This contribution reports on our work on triggering on short radio signals, post-event imaging of radio signals from buffered data and methods to determine the TEC-value

Cosmic Ray Mass Measurements with LOFAR

In the dense core of LOFAR individual air showers are detected by hundreds of dipole antennas simultaneously. We reconstruct Xmax by using a hybrid technique that combines a two-dimensional fit of the radio profile to CoREAS simulations and a one-dimensional fit of the particle density distribution. For high-quality detections, the statistical uncertainty on Xmax is smaller than 20 g/cm2. We present results of cosmic-ray mass analysis in the energy regime of 1017 - 1017.5 eV. This range is of particular interest as it may harbor the transition from a Galactic to an extragalactic origin of cosmic rays

Towards real-time identification of cosmic rays with LOw-Frequency ARray radio antennas

Contains fulltext : 173576.pdf (publisher's version ) (Open Access

Caltech Core-Collapse Project (CCCP) observations of type IIn supernovae: typical properties and implications for their progenitor stars

Type IIn Supernovae (SNe IIn) are rare events, constituting only a few percent of all core-collapse SNe, and the current sample of well observed SNe IIn is small. Here, we study the four SNe IIn observed by the Caltech Core-Collapse Project (CCCP). The CCCP SN sample is unbiased to the extent that object selection was not influenced by target SN properties. Therefore, these events are representative of the observed population of SNe IIn. We find that a narrow P-Cygni profile in the hydrogen Balmer lines appears to be a ubiquitous feature of SNe IIn. Our light curves show a relatively long rise time (>20 days) followed by a slow decline stage (0.01 to 0.15 mag/day), and a typical V-band peak magnitude of M_V=-18.4 +/- 1.0 mag. We measure the progenitor star wind velocities (600 - 1400 km/s) for the SNe in our sample and derive pre-explosion mass loss rates (0.026 - 0.12 solar masses per year). We compile similar data for SNe IIn from the literature, and discuss our results in the context of this larger sample. Our results indicate that typical SNe IIn arise from progenitor stars that undergo LBV-like mass-loss shortly before they explode.Comment: ApJ, submitte

The breakthrough listen search for intelligent life: a wideband data recorder system for the Robert C. Byrd green bank telescope

The Breakthrough Listen Initiative is undertaking a comprehensive search for radio and optical signatures from extraterrestrial civilizations. An integral component of the project is the design and implementation of wide-bandwidth data recorder and signal processing systems. The capabilities of these systems, particularly at radio frequencies, directly determine survey speed; further, given a fixed observing time and spectral coverage, they determine sensitivity as well. Here, we detail the Breakthrough Listen wide-bandwidth data recording system deployed at the 100-m aperture Robert C. Byrd Green Bank Telescope. The system digitizes up to 6 GHz of bandwidth at 8 bits for both polarizations, storing the resultant 24 GB/s of data to disk. This system is among the highest data rate baseband recording systems in use in radio astronomy. A future system expansion will double recording capacity, to achieve a total Nyquist bandwidth of 12 GHz in two polarizations. In this paper, we present details of the system architecture, along with salient configuration and disk-write optimizations used to achieve high-throughput data capture on commodity compute servers and consumer-class hard disk drives