We measure the rates of type I X-ray bursts from a likely flux-limited sample of 37 nonpulsing Galactic transients observed with RXTE during 1996-2004. These sources are well categorized in the literature as either neutron star systems or black hole candidates. Our goals are to test the burst model for neutron stars and to investigate whether black holes have event horizons. Target selection is one of several differences between the present study and the investigation of the event horizon question by Tournear and coworkers. Burst rates are measured as a function of bolometric luminosity, and the results are compared with augmented versions of the burst model developed by Narayan & Heyl. For a given mass, we consider a range in both the radius and the temperature at the boundary below the accretion layer. We find 135 spectrally confirmed type I bursts in 3.7 Ms of PCA exposures for the neutron star group (13 sources), and the burst rate function is generally consistent with the model predictions. However, for the black hole groups (18 sources), there are no confirmed type I bursts in 6.5 Ms of exposure, and the upper limits in the burst function are inconsistent with the model predictions for heavy compact objects with a solid surface. The consistency probability is ~2 × 10-7 for dynamical black hole binaries, falling to 3 × 10-13 with the added exposures of black hole candidates. Furthermore, there are systematic spectral differences between the neutron star and black hole groups, supporting the presumption that physical differences underly the classifications in our sample. These results provide indirect evidence that black holes do have event horizons.
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机译：我们从1996-2004年用RXTE观测到的37个非脉冲银河瞬变的通量受限样品中测量了I型X射线爆发的速率。这些来源在文献中被很好地归类为中子星系统或黑洞候选者。我们的目标是测试中子星的爆发模型并研究黑洞是否具有事件视界。目标选择是当前研究与Tournear及其同事对事件范围问题的调查之间的几个差异之一。测量爆破率作为辐射热亮度的函数，并将结果与Narayan＆Heyl开发的爆破模型的增强版本进行比较。对于给定的质量，我们考虑吸积层下方边界处的半径和温度范围。我们在中子星群（13个源）的3.7 Ms PCA暴露中发现了135个经光谱确认的I型爆发（13个源），并且爆发速率函数通常与模型预测一致。但是，对于黑洞组（18个源），在6.5 Ms的曝光中没有确定的I型爆发，并且爆发函数的上限与具有固体表面的重质紧凑物体的模型预测不一致。动态黑洞二进制文件的一致性概率约为2×10-7，随着黑洞候选图像的增加，其一致性概率降至3×10-13。此外，在中子星和黑洞群之间存在系统的光谱差异，支持这样的假设，即我们样本中的物理差异是分类的基础。这些结果间接证明了黑洞确实具有事件视界。
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