论文标题
用Lamost和SDS表征一些Gaia警报
Characterizing Some Gaia Alerts with LAMOST and SDSS
论文作者
论文摘要
盖亚（Gaia）定期在检测到光度变异性的对象上发出警报。这些物体的物理性质通常必须通过基于地面设施的互补观测来确定。我们已经将Gaia警报列表（直到20181101）与存档Lamost和SDSS光谱数据进行了比较。基于地面观察的日期很少与警报的日期相对应，但是如果源是持续的，则至少可以识别源，或者如果对象仅像超新星一样瞬时，则允许主机银河系。来自Kostrzewa-Rutkowska等人的Gaia核瞬变列表。 （2018年）也包括在此搜索中。我们在lamost+SDSS中发现了26个盖亚警报，标记为恒星（12个具有多个谱光谱）。其中大多数是简历。同样，有206个Gaia警报也将标记为星系的光谱（49个带有多个上述光谱）。这些光谱通常是在与警报日期不同的日期中获得的，主要是排放线星系，导致人们怀疑大多数警报是由于SN引起的。至于GNT列表，我们发现了55个标记为星系的相关光谱（13个具有多个上述光谱）。在两个星系中，Gaia17aal和GNTJ170213+2543是光谱观察的日期，足够接近机敏日期：我们在其板摩斯特频谱中发现了SN本身的痕迹，在此均分类为IA型SN。 GNT样品的AGN比例较高，这表明某些检测到的变化也是由于AGN本身引起的。类星体类似，我们发现了30个Gaia警报，但68个GNT案例具有单个时期的类星体光谱，而12加23个具有多上段光谱。在这35个中的十个中，它们的多上谱谱显示了宽Balmer线的外观或消失以及连续体的变化，将它们视为“变化的样品”。
Gaia is regularly producing Alerts on objects where photometric variability has been detected. The physical nature of these objects has often to be determined with the complementary observations from ground-based facilities. We have compared the list of Gaia Alerts (until 20181101) with archival LAMOST and SDSS spectroscopic data. The date of the ground-based observation rarely corresponds to the date of the Alert, but this allows at least the identification of the source if it is persistent, or the host galaxy if the object was only transient like a supernova. A list of Gaia Nuclear Transients from Kostrzewa-Rutkowska et al. (2018) has been included in this search also. We found 26 Gaia Alerts with spectra in LAMOST+SDSS labelled as stars (12 with multi-epoch spectra). A majority of them are CVs. Similarly 206 Gaia Alerts have associated spectra labelled as galaxies (49 with multi-epoch spectra). Those spectra were generally obtained on a date different from the Alert date, are mostly emission-line galaxies, leading to the suspicion that most of the Alerts were due to a SN. As for the GNT list, we found 55 associated spectra labelled as galaxies (13 with multi-epoch spectra). In two galaxies, Gaia17aal and GNTJ170213+2543, was the date of the spectroscopic observation close enough to the Alert date: we find a trace of the SN itself in their LAMOST spectrum, both classified here as a type Ia SN. The GNT sample has a higher proportion of AGNs, suggesting that some of the detected variations are also due to the AGN itself. Similar for Quasars, we found 30 Gaia Alerts but 68 GNT cases have single epoch quasar spectra, while 12 plus 23 have multi-epoch spectra. For ten out of these 35, their multi-epoch spectra show appearance or disappearance of the broad Balmer lines and also variations in the continuum, qualifying them as "Changing Look Quasars".
