A search for thermally emitting isolated neutron stars in the 2XMMp catalogue
A search for thermally emitting isolated neutron stars in the 2XMMp catalogue
复制标题
在 2XMMp 目录中搜索热发射孤立中子星
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Brazil.
中科院分区：
文献类型：
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作者：
A. Pires;C. Motch;Eduardo Janot;Strasbourg;France.;IAG;Brazil.
ROSAT AllSky 巡天中发现的附近相对大量的射电安静且热发射的孤立中子星（INS）被称为“七大星”，这表明它们属于以前被忽视的整个 INS 种群的主要组成部分。到目前为止，在太阳附近发现类似惯性导航系统的尝试未能确认任何可靠的候选者。 XMM-Newton 卫星上的 EPIC 相机具有良好的位置精度和软 X 射线灵敏度，使我们能够有效地搜索新的热发射 INS。我们使用 2XMMp 目录来选择没有编目候选对应物的源，其 X 射线光谱与七大星相似，但在更远的距离处可见，因此经历了更高的星际吸收。通过对 170 多个天文目录的识别和目视筛选，我们仅选出了不到 30 个优秀的 INS 候选者。为了排除其他识别问题，我们获得了 X 射线最亮候选者的深度 ESO-VLT 和 SOAR 光学成像。我们在此报告我们搜索的光学后续结果，并讨论 8 名候选者的可能性质。高 X 射线与光通量比以及稳定的通量和软 X 射线光谱使我们的样品 2XMM J104608.7-594306 成为最亮的光源，它是一种新发现的热发射 INS。 X 射线源 2XMM J010642.3+005032 没有明显的光学对应物，应进一步研究。根据其可能的光学对应物的颜色和通量比推断，剩余的 X 射线源很可能被识别为灾难变星和活跃星系核。除了发现新的热发射惯性导航系统之外，我们的研究还旨在限制远距离银河系种群的空间密度，并确定它们明显的高密度是否是局部异常。
The relatively large number of nearby radio-quiet and thermally emitting isolated neutron stars (INSs) discovered in the ROSAT AllSky Survey, dubbed the “Magnificent Seven”, suggests that they belong to a formerly neglected major component of the overall INS population. So far, attempts to discover similar INSs beyond the solar vicinity failed to confirm any reliable candidate. The good positional accuracy and soft X-ray sensitivity of the EPIC cameras onboard the XMM-Newton satellite allow us to efficiently search for new thermally emitting INSs. We used the 2XMMp catalogue to select sources with no catalogued candidate counterparts and with X-ray spectra similar to those of the Magnificent Seven, but seen at greater distances and thus undergoing higher interstellar absorptions. Identifications in more than 170 astronomical catalogues and visual screening allowed us to select fewer than 30 good INS candidates. In order to rule out alternative identifications, we obtained deep ESO-VLT and SOAR optical imaging for the X-ray brightest candidates. We report here on the optical follow-up results of our search and discuss the possible nature of 8 of our candidates. A high X-ray-to-optical flux ratio together with a stable flux and soft X-ray spectrum make the brightest source of our sample, 2XMM J104608.7-594306, a newly discovered thermally emitting INS. The X-ray source 2XMM J010642.3+005032 has no evident optical counterpart and should be further investigated. The remaining X-ray sources are most probably identified with cataclysmic variables and active galactic nuclei, as inferred from the colours and flux ratios of their likely optical counterparts. Beyond the finding of new thermally emitting INSs, our study aims at constraining the space density of this Galactic population at great distances and at determining whether their apparently high density is a local anomaly or not.