Parkes observations for project P1028 semester 2019OCTS_03

In order to effectively target searches for pulsars near the black hole Sgr A*, we need a better understanding of both the Galactic center pulsar population and the magneto-ionic environment in which they reside. The radio-emitting magnetar J1745-2900 has been studied in great detail since it was discovered in 2013, but far less is known of the other five pulsars within 30 arcmin (~70 pc) of Sgr A*. A few flux density and scattering measurements have been made over the last ~10 years at a few frequencies at different epochs, but no systematic wide-band study has yet been performed. Motivated by the first re-detection of J1746-2850 since 2012, we propose deep observations of these five pulsars using the UWL from 700-4000 MHz. From these observations, we will precisely measure the pulse broadening times for each pulsar as well as their frequency evolution in the range where scattering becomes dominant. Wide-band measurements of the scattering parameters will constrain the size and distribution of scattering material along the line of sight and inform future Galactic center pulsar searches.

为了有效针对黑洞Sgr A*附近的脉冲星（pulsar）开展搜索，我们需要更深入地理解银心脉冲星群体以及它们所处的磁离子环境（magneto-ionic environment）。射电辐射磁星（magnetar）J1745-2900自2013年被发现以来已得到详尽研究，但对于Sgr A*周围30角分（~70秒差距，pc）内的其他五颗脉冲星，我们所知甚少。过去约10年间，人们在不同历元、少数频率下开展了若干流量密度（flux density）和散射（scattering）测量，但尚未进行系统性的宽带研究。受2012年以来首次重新探测到J1746-2850的启发，我们提议使用700-4000 MHz的UWL对这五颗脉冲星开展深度观测。通过这些观测，我们将精确测量每颗脉冲星的脉冲展宽时间（pulse broadening time），以及在散射占主导地位的频率范围内它们的频率演化。散射参数（scattering parameter）的宽带测量将约束视线方向上散射物质的大小与分布，并为未来的银心脉冲星搜索提供参考。