XMM-Newton follow-up of two eROSITA X-ray binary candidates

IF 2.2 3区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Experimental Astronomy Pub Date : 2025-07-09 DOI:10.1007/s10686-025-10016-w

A. Avakyan, A. Zainab, V. Doroshenko, J. Wilms, A. Schwope, V. Suleimanov, D. Buckley, J. Brink, A. Santangelo

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Abstract

We report on the follow-up observations with XMM-Newton of two X-ray binary candidates identified in the first eROSITA all-sky survey data (eRASS1), 1eRASS J061330.8\(+\)160440 and 1eRASS J161201.9−464622. Based on the obtained results, in particular, the observed X-ray spectra and lack of pulsations, as well as properties of the identified optical counterparts, we conclude that both candidates are unlikely to be XRBs. Based on LAMOST optical spectroscopy and SED fit results for 1eRASS J061330.8\(+\)160440 we classify it as an M0 chromospherically active subgiant star. ZTF and TESS photometry reveal highly significant period for this object of 7.189 days, which likely attributed to starspot(s). On the other hand, SALT follow-up spectroscopy of 1eRASS J161201.9−464622 solidly classifies this source as a bright novalike cataclysmic variable (CV), the second discovered with eROSITA. A persistent 4.802 h signal is found across all three available TESS observations, and is tentatively identified as the orbital period of the binary. Follow-up high-speed photometry and time-resolved spectroscopy are required to confirm the derived orbital modulation.

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xmm -牛顿对两个eROSITA x射线双星候选者的随访

我们报告了XMM-Newton对第一次eROSITA全天巡天数据（eRASS1）中确定的两个x射线双星候选天体1eRASS J061330.8 \(+\) 160440和1eRASS J161201.9−464622的后续观测。根据所获得的结果，特别是观察到的x射线光谱和缺乏脉动，以及所识别的光学对应物的性质，我们得出结论，这两个候选物不太可能是XRBs。基于对1eRASS J061330.8 \(+\) 160440的LAMOST光谱和SED拟合结果，我们将其归类为M0色球活动亚巨星。ZTF和TESS的光度测量显示，这个天体的周期非常明显，为7.189天，这可能归因于恒星黑子。另一方面，1eRASS J161201.9−464622的SALT后续光谱将该源明确地归类为明亮的新星样突变变量（CV），这是eROSITA发现的第二个源。在所有三个可用的TESS观测中都发现了一个持续的4.802小时的信号，并初步确定为双星的轨道周期。需要后续的高速测光和时间分辨光谱来证实推导出的轨道调制。

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来源期刊

Experimental Astronomy 地学天文-天文与天体物理

CiteScore

5.30

自引率

3.30%

发文量

审稿时长

6-12 weeks

期刊介绍： Many new instruments for observing astronomical objects at a variety of wavelengths have been and are continually being developed. Furthermore, a vast amount of effort is being put into the development of new techniques for data analysis in order to cope with great streams of data collected by these instruments. Experimental Astronomy acts as a medium for the publication of papers of contemporary scientific interest on astrophysical instrumentation and methods necessary for the conduct of astronomy at all wavelength fields. Experimental Astronomy publishes full-length articles, research letters and reviews on developments in detection techniques, instruments, and data analysis and image processing techniques. Occasional special issues are published, giving an in-depth presentation of the instrumentation and/or analysis connected with specific projects, such as satellite experiments or ground-based telescopes, or of specialized techniques.