Discovery of a New Redback Millisecond Pulsar Candidate: 4FGL J0940.3–7610
Discovery of a New Redback Millisecond Pulsar Candidate: 4FGL J0940.3–7610
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DOI：
10.3847/1538-4357/abe1be
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发表时间：
2021-01
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通讯作者：
S. Swihart;J. Strader;E. Aydi;L. Chomiuk;K. Dage;L. Shishkovsky
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作者：
S. Swihart;J. Strader;E. Aydi;L. Chomiuk;K. Dage;L. Shishkovsky
我们在明亮的非伴生Fermi-LAT γ射线源4FGL J0940.3-7610的误差椭圆中心附近发现了一个新的候选红背毫秒脉冲星双星。候选对应物是一个可变光源，也显示微弱的x射线发射。SOAR望远镜的光度和光谱监测表明，伴星是一颗低质量恒星，围绕一颗不可见的主恒星运行6.5小时，显示出椭圆变化和辐射，与已知红背毫秒脉冲星双星的特性一致。考虑到轨道参数，光学光曲线的初步建模表明，这是一颗边对着的倾角和一颗低质量（约1.2-1.4 M⊙）中子星，以及一颗比典型的约0.4 M⊙质量更大的次级质量。这种倾角和次级性质的结合可能使这个系统更有可能发生射电日食，这解释了它以前在射电脉冲搜索中没有被发现的原因。因此，4FGL J0940.3-7610可能是集中搜索γ射线脉冲的有力候选者，从而能够在未来探测到毫秒脉冲星。
We have discovered a new candidate redback millisecond pulsar binary near the center of the error ellipse of the bright unassociated Fermi-LAT γ-ray source 4FGL J0940.3–7610. The candidate counterpart is a variable optical source that also shows faint X-ray emission. Optical photometric and spectroscopic monitoring with the SOAR telescope indicates that the companion is a low-mass star in a 6.5 hr orbit around an invisible primary, showing both ellipsoidal variations and irradiation and consistent with the properties of known redback millisecond pulsar binaries. Given the orbital parameters, preliminary modeling of the optical light curves suggests an edge-on inclination and a low-mass (∼1.2–1.4 M ⊙) neutron star, along with a secondary mass somewhat more massive than the typical ≳0.4 M ⊙. This combination of inclination and secondary properties could make radio eclipses more likely for this system, explaining its previous nondiscovery in radio pulsation searches. Hence, 4FGL J0940.3–7610 may be a strong candidate for a focused search for γ-ray pulsations to enable the future detection of a millisecond pulsar.