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arXiv 0911.0872astro-ph.HE
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利用费米大面积望远镜的光变曲线探测毫秒脉冲星发射几何

Probing millisecond pulsar emission geometry using light curves from the Fermi Large Area Telescope

C. Venter, A. K. Harding, L. Guillemot

摘要:

一个有趣的新的高能脉冲星子群正在出现的早期发现的伽马射线毫秒脉冲星(MSP)的费米大面积望远镜(LAT)。我们提出的结果从3D发射建模,包括特殊的相对论效应的像差和飞行时间延迟和旋转后掠的B场线,在几何背景下的极冠(PC),外间隙(OG),和两极焦散(TPC)脉冲星模型。一般认为,这些非常古老的,快速旋转的中子星(NS)应该有很大程度上对饥饿的磁层,由于没有显着的对生产,我们发现,大多数的光变曲线是最好的TPC和OG模型,这表明存在狭窄的加速间隙限制强大的对生产-即使在这些恒星非常低的自旋下降光度。伽马射线脉冲形状和相对于无线电脉冲的相对相位滞后表明,高空发射对所有几何形状都占主导地位。我们还发现,目前的伽马射线MSP人口的两个MSP子类的独家分化:光变曲线的形状和滞后波带施加对饥饿的PC(PSPC)或TPC /OG型的几何形状。在第一种情况下,无线电脉冲相对于单个伽马射线脉冲具有小的滞后,而在后一种情况下,(第一个)伽马射线峰值通常以大的相位偏移落后于无线电。最后,我们发现,磁通校正因子作为磁倾角和观测器角度的函数,通常是所有模型的顺序统一。因此,我们对MSP的光变曲线和通量校正因子的计算是对Watters等人的“ATLAS论文”的补充。

英文摘要:

An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of B-field lines, in the geometric context of polar cap (PC), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by TPC and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or TPC / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

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