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arXiv 1504.02492astro-ph.HE
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银心毫秒脉冲星的探测

On Detecting Millisecond Pulsars at the Galactic Center

Jean-Pierre Macquart, Nissim Kanekar

摘要:

在银河系中心(GC)区域缺乏探测到的恒星是一个长期存在的谜团。我们认为,在中央秒差距周围的GC的高恒星密度可能会导致脉冲星人口占主导地位的毫秒双星(MSP),类似的情况下,在球状星团的环境。早期的GC脉冲星搜索在很大程度上对这样的MSP种群不敏感,这是缺乏脉冲星探测的原因。我们估计这样一个MSP人口的最佳搜索频率与目前和即将到来的宽带射电望远镜的两种可能的散射情况下,“弱散射”的情况下,建议最近检测到的磁星接近GC,和“强散射”的情况下,与散射屏幕位于GC附近。对于周期为1-20 ms的类星体,最佳搜索频率分别为$\approx 8$ GHz(弱散射)和$\approx 25$ GHz(强散射),假设GC类星体的光度分布与银河系其他部分相似。我们发现,10-30小时的集成与甚大阵列和绿岸望远镜将足以检测MSP在GC距离在弱散射的情况下。然而,如果强散射的情况确实适用于GC,则需要使用完整的平方公里阵列进行观测以检测推定的MSP群体。

英文摘要:

The lack of detected pulsars at the Galactic Center (GC) region is a long-standing mystery. We argue that the high stellar density in the central parsec around the GC is likely to result in a pulsar population dominated by millisecond pulsars (MSPs), similar to the situation in globular cluster environments. Earlier GC pulsar searches have been largely insensitive to such an MSP population, accounting for the lack of pulsar detections. We estimate the best search frequency for such an MSP population with present and upcoming broad-band radio telescopes for two possible scattering scenarios, the "weak-scattering" case suggested by the recent detection of a magnetar close to the GC, and the "strong-scattering" case, with the scattering screen located close to the GC. The optimal search frequencies are $\approx 8$ GHz (weak-scattering) and $\approx 25$ GHz (strong-scattering), for pulsars with periods 1-20 ms, assuming that GC pulsars have a luminosity distribution similar to that those in the rest of the Milky Way. We find that 10-30 hour integrations with the Very Large Array and the Green Bank Telescope would be sufficient to detect MSPs at the GC distance in the weak-scattering case. However, if the strong-scattering case is indeed applicable to the GC, observations with the full Square Kilometre Array would be needed to detect the putative MSP population.

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