标题： 发现1RXS J141256.0+792204（Calvera）的59毫秒脉冲 显示英文标题

标题： Discovery of 59ms Pulsations from 1RXS J141256.0+792204 (Calvera)

摘要： 我们报告了对致密天体候选体1RXS J141256.0+792204（Calvera）的多波段研究。Calvera曾两次用XMM/EPIC在X射线波段观测，总曝光时间为约50 ks。源谱呈热辐射，并且很好地由两组分模型再现，这两组分可以是两个氢大气模型，也可以是两个黑体（kT_1~ 55/150 eV, kT_2~ 80/250 eV，分别在无穷远处测量）。发现了一个大约在0.65 keV处的吸收特征；统计上不需要幂律高能尾。使用pn和MOS数据，我们在X射线发射中发现了周期P=59.2 ms的脉冲。该探测高度显著（> 11 sigma），明确证实了Calvera的中子星性质。脉冲轮廓接近正弦曲线，脉冲分数约为18%。我们在Fermi大面积望远镜（LAT）数据库中寻找Calvera的时间特征，并发现在X射线值一致的周期上存在显著（~5 sigma）的脉冲信号。伽马射线时间分析对周期导数给出了严格的上限，dP/dt < 5E-18 s/s（dE_rot/dt <1E33 erg/s，B<5E10 G，对于磁偶极减速）。使用100米Effelsberg射电望远镜在1.36 GHz的射电搜索结果为阴性，脉冲流深上限为0.05 mJy。在Calvera位置西边大约13'处存在弥漫、软（< 1 keV）的X射线发射，这在我们的指向观测和档案ROSAT全天巡天图像中均可见，但不太可能与X射线脉冲星相关。其光谱与古老超新星遗迹（SNR）一致；未在射电和光学波段发现弥漫发射。最可能的解释是Calvera要么是从超新星遗迹逃逸的中心致密天体，要么是轻微再循环的脉冲星；在这两种情况下，该源将是首次以伽马射线能量检测到的此类天体成员之一。 显示英文摘要

摘要： We report on a multi-wavelength study of the compact object candidate 1RXS J141256.0+792204 (Calvera). Calvera was observed in the X-rays with XMM/EPIC twice for a total exposure time of ~50 ks. The source spectrum is thermal and well reproduced by a two component model composed of either two hydrogen atmosphere models, or two blackbodies (kT_1~ 55/150 eV, kT_2~ 80/250 eV, respectively, as measured at infinity). Evidence was found for an absorption feature at ~0.65 keV; no power-law high-energy tail is statistically required. Using pn and MOS data we discovered pulsations in the X-ray emission at a period P=59.2 ms. The detection is highly significant (> 11 sigma), and unambiguously confirms the neutron star nature of Calvera. The pulse profile is nearly sinusoidal, with a pulsed fraction of ~18%. We looked for the timing signature of Calvera in the Fermi Large Area Telescope (LAT) database and found a significant (~5 sigma) pulsed signal at a period coincident with the X-ray value. The gamma-ray timing analysis yielded a tight upper limit on the period derivative, dP/dt < 5E-18 s/s (dE_rot/dt <1E33 erg/s, B<5E10 G for magneto- dipolar spin-down). Radio searches at 1.36 GHz with the 100-m Effelsberg radio telescope yielded negative results, with a deep upper limit on the pulsed flux of 0.05 mJy. Diffuse, soft (< 1 keV) X-ray emission about 13' west of the Calvera position is present both in our pointed observations and in archive ROSAT all-sky survey images, but is unlikely associated with the X-ray pulsar. Its spectrum is compatible with an old supernova remnant (SNR); no evidence for diffuse emission in the radio and optical bands was found. The most likely interpretations are that Calvera is either a central compact object escaped from a SNR or a mildly recycled pulsar; in both cases the source would be the first ever member of the class detected at gamma-ray energies.