低质量XMM-牛顿2型有源半导体激光器的发射和吸收特性
Emission and Absorption Properties of Low-Mass Type 2 Active Galaxies with XMM-Newton
摘要：
我们选取了4个低红移的Seyfert星系进行XMM-牛顿观测，这些星系具有低的主光度（M_g>-20等）和小的恒星速度色散（sigma_star<45 km/s），它们是所有活动星系中发现的最小的恒星速度色散。这些星系显示出微弱或没有宽的光学发射线，并且可能有质量小于10^6太阳质量的黑洞。四个物体中有三个在~25 ks曝光中检测到> 3 σ显著性，两个观测值具有足够高的信噪比，可用于基本光谱分析。我们计算硬度比（-0.43至0.01）的三个检测到的对象，并使用它们来估计光子指数的范围内的伽玛=1.1-1.8。相对于[OIII]，2型天体与塞弗特1型星系相比X射线微弱，这表明中央引擎被遮蔽了。我们估计每个对象的固有吸收的假设下，[OIII]发射线的光度与未吸收的X射线光度。结果与四个天体中的三个在银河系范围内的中等吸收（N_H~10^22 cm^-2）相一致，这可能解释了光谱中没有检测到宽线发射。我们样本中的一个物体，SDSS J110912.40+612346.7，是一个与晚型塞弗特1星系NGC 4395几乎相同的2型对应物。虽然这两个天体的[OIII]光度非常相似，但2型天体的X射线/[OIII]通量比比NGC 4395低近一个数量级。对这种差异最合理的解释是2型天体的主X射线连续谱的吸收，这表明基于遮蔽的活动星系统一模型即使在塞弗特核中可见的最低光度下也适用，低至L_bol~10^40-10^41 erg/s。
英文摘要：
We present XMM-Newton observations of four low-redshift Seyfert galaxies selected to have low host luminosities (M_g>-20 mag) and small stellar velocity dispersions (sigma_star<45 km/s), which are among the smallest stellar velocity dispersions found in any active galaxies. These galaxies show weak or no broad optical emission lines and have likely black hole masses <10^6 M_sun. Three out of four objects were detected with >3sigma significance in ~25 ks exposures and two observations had high enough signal-to-noise ratios for rudimentary spectral analysis. We calculate hardness ratios (-0.43 to 0.01) for the three detected objects and use them to estimate photon indices in the range of Gamma=1.1-1.8. Relative to [OIII], the type 2 objects are X-ray faint in comparison with Seyfert 1 galaxies, suggesting that the central engines are obscured. We estimate the intrinsic absorption of each object under the assumption that the [OIII] emission line luminosities are correlated with the unabsorbed X-ray luminosity. The results are consistent with moderate (N_H~10^22 cm^-2) absorption over the Galactic values in three of the four objects, which might explain the non-detection of broad-line emission in optical spectra. One object in our sample, SDSS J110912.40+612346.7, is a near identical type 2 counterpart of the late-type Seyfert 1 galaxy NGC 4395. While the two objects have very similar [OIII] luminosities, the type 2 object has an X-ray/[OIII] flux ratio nearly an order of magnitude lower than NGC 4395. The most plausible explanation for this difference is absorption of the primary X-ray continuum of the type 2 object, providing an indication that obscuration-based unified models of active galaxies can apply even at the lowest luminosities seen among Seyfert nuclei, down to L_bol~10^40-10^41 erg/s.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
