A SETI Survey of the Vela Region using the Murchison Widefield Array: Orders of Magnitude Expansion in Search Space (2009.03267v1)

Abstract: Following the results of our previous low frequency searches for extraterrestrial intelligence (SETI) using the Murchison Widefield Array (MWA), directed toward the Galactic Centre and the Orion Molecular Cloud (Galactic Anticentre), we report a new large-scale survey toward the Vela region with the lowest upper limits thus far obtained with the MWA. Using the MWA in the frequency range 98-128 MHz over a 17 hour period, a $\sim$400 deg$^2$ field centred on the Vela Supernova Remnant was observed with a frequency resolution of 10 kHz. Within this field there are six known exoplanets. At the positions of these exoplanets, we searched for narrow band signals consistent with radio transmissions from intelligent civilizations. No unknown signals were found with a 5sigma detection threshold. In total, across this work plus our two previous surveys, we have now examined 75 known exoplanets at low frequencies. In addition to the known exoplanets, we have included in our analysis the calculation of the Effective Isotropic Radiated Power (EIRP) upper limits toward over 10 million stellar sources in the Vela field with known distances from Gaia (assuming a 10 kHz transmission bandwidth).

• The paper demonstrates an orders-of-magnitude expansion in SETI search space by analyzing over 10 million stars with data from the Gaia catalog.
• It utilizes the MWA to observe a 400-square degree region over 17 hours, targeting six exoplanets for narrow-band signals at a 5σ detection threshold.
• The study integrates SETI into routine astrophysical surveys by establishing competitive EIRP upper limits and paving the way for future instruments like the SKA.

A SETI Survey of the Vela Region using the Murchison Widefield Array

The paper presents a comprehensive Search for Extraterrestrial Intelligence (SETI) survey directed towards the Vela region using the Murchison Widefield Array (MWA). This paper is a continuation of previous low-frequency SETI searches targeting significant celestial regions such as the Galactic Centre and the Orion Molecular Cloud. The current survey outlines the strategic enhancement in search space, making significant strides with the lowest upper limits achieved so far by the MWA.

The observational paper utilized the MWA within the frequency range of 98-128 MHz over a period of 17 hours, focusing on a 400 square degree field centered on the Vela Supernova Remnant. A total of six exoplanets within this field were analyzed for narrow-band signals indicative of potential intelligent extraterrestrial radio transmissions. Despite achieving a 5σ detection threshold, no unknown signals were detected across these targets.

Crucially, this work extends the scope to over 10 million stellar sources with known distances provided by the Gaia data, calculating the Effective Isotropic Radiated Power (EIRP) upper limits, assuming a 10 kHz transmission bandwidth. When placed in the context of an eight-dimensional parameter space for SETI searches, as described by previous studies, this survey notably reaches a search fraction of approximately $2 \times 10^{-16}$. This represents an improvement of two orders of magnitude over earlier surveys using the MWA, showcasing an expansive search space exploration.

The findings are contextualized within the broader spectrum of SETI endeavors, represented in the EIRP$_{\text{min}}$ - Transmitter Rate plane. Although the MWA survey demonstrates substantial progress in setting competitive limits on potential extraterrestrial signals, it simultaneously reflects on the extensive parameter space that remains unexplored in SETI research. The authors highlight the capability of large-scale surveys, especially those conducted with radio telescopes having expansive fields-of-view, to facilitate commensal data acquisition for both astrophysical observations and SETI purposes. This approach not only augments the efficiency of data collection but also fosters a multifaceted usage of available resources in radio astronomy.

In the field of practical implications, the paper underscores the evolution of SETI methodologies, emphasizing the importance of integrating SETI objectives into routine astrophysical surveys. By leveraging instruments designed for comprehensive celestial surveys, commensal SETI searches can capitalize on the wealth of data, ensuring incremental yet impactful progress in the search for extraterrestrial intelligence. Theoretical implications suggest that the integration of expansive stellar catalogs such as Gaia with SETI surveys heralds a promising avenue for future explorations, potentially offering insights into the prevalence of technosignatures within the galaxy.

As SETI continues to develop, the paper envisions future enhancements in both analytical methodology and instrumental sensitivities. The authors posit that forthcoming arrays like the Square Kilometre Array (SKA) will play a pivotal role in advancing the search for technosignatures, promising a significant reduction in the expansive parameter space that remains largely unexplored.

This paper provides a methodologically robust framework and empirical data set that bolster current SETI research and lay the groundwork for future investigations, both within the MWA and in the context of emerging radio astronomy technologies. The findings demonstrate a persistent trajectory of progress and innovation within the domain of SETI, fostering a nuanced understanding of extraterrestrial search efforts in a rapidly evolving astrophysical landscape.