论文标题
朝向银河平面的中级极性候选者
An intermediate polar candidate toward the Galactic plane
论文作者
论文摘要
在过去的十年中，有人提出中间球（IPS）是磁性灾难性变量（CVS）的亚类，是从银河系中心（GC）和银河系脊的硬弥漫性X射线发射的主要贡献者之一。在我们正在进行的\ emph {xmm-newton}对银河磁盘中心区域的调查（$ 20^\ circ \ times2^\ circ $），我们检测到了一个持久的IP候选者，$ 1.7^\ Circ $远离GC。在这项工作中，我们通过查看新的和档案XMM-Newton数据来更好地表征该来源的行为。我们对源进行了详细的X射线光谱建模。此外，我们在光曲线中搜索了X射线搏动，并在其他波长处搜索了X射线脉动。源的XMM-Newton光谱（0.8--10 KEV）通过部分覆盖碰撞的散射弥漫性气体$ kt = 15.7^{+20.9} _ { - 3.6} $ kev来描述。此外，频谱显示了$ e = 6.44 $，6.65和6.92 keV的铁线的存在，其等效宽度为$ 194^{+89} _ { - 70} $，$ 115^{+79} _ {+79} _ { - 75} $，以及$ 98^^{+93} $ 93} $} X射线灯曲线显示了一个连贯的调制，其周期为$ P = 432.44 \ pm0.36 $ s，我们推断为白矮人的旋转周期。从拟合物理模型到频谱的估计的白矮质量会导致$ m _ {\ rm wd} = 1.05^{+0.16} _ { - 0.21} \ m _ {\ odot} $。我们能够在Gaia目录中找到一个可能的光学对应物，其G幅度为19.26，并且与测量的Gaia Parallax得出的源的距离为$ \ sim $ 4.3 kpc。我们以SubarcSec精度提供了改进的源本地化。来源的光谱建模表明存在中间气体，从而吸收了软X射线光子。测得的铁线的等效宽度和光曲线中自旋周期的检测与IP的宽度一致。
For the past decade, it has been suggested that intermediate polars (IPs), a subclass of magnetic cataclysmic variables (CVs), are one of the main contributors to the hard diffuse X-ray emission from the Galactic center (GC) and Galactic ridge. In our ongoing \emph{XMM-Newton} survey of the central region of the Galactic disk ($20^\circ\times2^\circ$), we detected a persistent IP candidate, $1.7^\circ$ away from the GC. In this work, we better characterize the behavior of this source by looking at the new and archival XMM-Newton data. We performed a detailed X-ray spectral modeling of the source. Furthermore, we searched for X-ray pulsations in the light curve as well as its counterpart at other wavelengths. The XMM-Newton spectrum (0.8--10 keV) of the source is described by a partial covering collisionally ionized diffuse gas with plasma temperature $kT=15.7^{+20.9}_{-3.6}$ keV. In addition, the spectrum shows the presence of iron lines at $E=6.44$, 6.65, and 6.92 keV with equivalent widths of $194^{+89}_{-70}$, $115^{+79}_{-75}$, and $98^{+93}_{-74}$ eV, respectively. The X-ray light curve shows a coherent modulation with a period of $P=432.44\pm0.36$ s, which we infer is the spin period of the white dwarf. The white dwarf mass estimated from fitting a physical model to the spectrum results in $M_{\rm WD}=1.05^{+0.16}_{-0.21}\ M_{\odot}$. We were able to find a likely optical counterpart in the Gaia catalog with a G magnitude of 19.26, and the distance to the source derived from the measured Gaia parallax is $\sim$4.3 kpc. We provide an improved source localization with subarcsec accuracy. The spectral modeling of the source indicates the presence of intervening circumstellar gas, which absorbs the soft X-ray photons. The measured equivalent width of the iron lines and the detection of the spin period in the light curve are consistent with those from IPs.
