The relatively large number of nearby radio-quiet and thermally emitting isolated neutron stars (INSs) discovered in the ROSAT All-Sky Survey, dubbed the ``Magnificent Seven'' (M7), 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 EPIC cameras onboard the XMM-Newton satellite allow 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 M7, but seen at greater distances and thus undergoing higher interstellar absorptions. Identifications in more than 170 astronomical catalogues and visual screening allowed 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 CVs and AGN, 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.
Painting a full radio sky -- Empirical mock catalogues with multiple source populations for future radio surveys
INAF - Institute of Radio Astronomy (IRA)（国家天体物理研究所射电天文研究所）；Scuola Internazionale Superiore di Studi Avanzati (SISSA)（高等高级研究国际学院）；Institute for Fundamental Physics of the Universe (IFPU)（宇宙基础物理研究所）；SKA Organization（平方公里阵列望远镜组织）；Observatoire de la Côte d’Azur (OCA)（蔚蓝海岸天文台）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio (OAS)（国家天体物理研究所天体物理学与空间科学观测站）；Astronomical Observatory of the Autonomous Region of Aosta Valley (OAVdA)（瓦莱达奥斯塔自治大区天文台）；INAF - Institute of Space Astrophysics and Cosmic Physics (IASF)（国家天体物理研究所空间天体物理学与宇宙物理学研究所）
A catalogue sample of low mass galaxies observed in X-rays with central candidate black holes
本文给出了51个低质量星系中$X$射线选择的候选黑洞的样本，其质量为$z\le 0.055$ {和质量为$10^{10}$ M $_{\odot}$ }是由NASA-SLOAN星系图和3XMM星表互相关得到的。{We我还在现有的目录中搜索了黑洞候选者的无线电对应物，发现以前选择的19个源也有无线电对应物。我们的结果表明，我们的样品主机{一个$X$射线源}（与无线电对应物有关）的星系中约有$37\%$与星系中心在空间上重合，与{其他最近的工作}一致。对于这些{ \it核}源，$X$ -射线/射电基本平面关系允许人们估计（中心）候选黑洞的质量，其结果在$10^{4}-2\times10^{8}$ M $_{\odot}$范围内（中值为$\simeq 3\times 10^7$ M $_{\odot}$，八个候选黑洞的质量低于$10^{7}$ M $_{\odot}$）。这一结果表明，低质量星系中发射$X$射线的黑洞可能在这类系统的演化中起着关键作用，同时也使解释星系中如此巨大的物体是如何形成的变得更加紧迫。{Of当然，为了证实我们的结果，在$X$射线和射电波段以及光学波段进行专门的跟踪观测是必要的
