A High-Frequency Search for Pulsars Within the Central Parsec of SgrA*

TL;DR

This study conducted a deep high-frequency search for pulsars near Sgr A* using the Green Bank Telescope at 15 GHz, achieving the highest frequency to date for such searches, but found no candidates, setting upper limits on pulsar population.

Contribution

First high-frequency (15 GHz) pulsar search in the Galactic Center, improving detection sensitivity and constraining the pulsar population near Sgr A*.

Findings

No pulsar candidates detected at 15 GHz.

Achieved a detection threshold of ~10 μJy.

Estimated an upper limit of 90 pulsars within the central parsec.

Abstract

We report results from a deep high-frequency search for pulsars within the central parsec of Sgr A* using the Green Bank Telescope. The observing frequency of 15 GHz was chosen to maximize the likelihood of detecting normal pulsars (i.e. with periods of $\sim 500$\,ms and spectral indices of $\sim -1.7$) close to Sgr A*, that might be used as probes of gravity in the strong-field regime; this is the highest frequency used for such pulsar searches of the Galactic Center to date. No convincing candidate was detected in the survey, with a $10\sigma$ detection threshold of $\sim 10 \mu$Jy achieved in two separate observing sessions. This survey represents a significant improvement over previous searches for pulsars at the Galactic Center and would have detected a significant fraction ($\gtrsim 5%) of the pulsars around Sgr A*, if they had properties similar to those of the known population. Using our best current knowledge of the properties of the Galactic pulsar population and the scattering material toward Sgr A*, we estimate an upper limit of 90 normal pulsars in orbit within the central parsec of Sgr A*.