M31核心星团的高分辨率紫外与光学研究
发布时间：2018-12-21 15:12
【摘要】：我们利用哈勃空间望远镜(HST)的紫外与光学波段的图像与光谱,对M31中心黑洞及其周围几个秒差距内的恒星(即核心星团)进行研究。M31的核心区域,存在面亮度的双峰分布,其中光学更亮的峰值被称为P1,光学暗一些的峰值被称为P2;而在紫外波段,P2的亮度超过P1。根据动力学信息的探测,人们发现超大质量黑洞M31*位于P2的内部。为了研究M31*的辐射和周围核心星团的物理性质,我们做了以下工作。我们利用HST/COS的近紫外波段的图像,对M31*进行了相距44天的两次观测。我们发现,距离M31*中心0.1角秒的测光孔径内,在紫外波段拥有(6.9±3.0)×10-18 erg·s-1·cm-2 A-1的流量差异。我们将M31*在X射线波段的光度外推到紫外波段,得到M31*的平均流量为1.7×10-18 erg·s-1·cm2·A-1。观测得到的流量差异4倍于该平均流量,因此该差异很可能来自于中心黑洞的光度变化。我们利用HST/WFC3的从近紫外波段到近红外波段共计10个图像的数据,对M31的核心星团进行了测光分析。我们发现P1内部除了存在一个质量为1.54-0.05+0.08×106 M& 的接近宇宙年龄、金属丰度为2.5倍太阳丰度的年老星族成分以外,还有一个质量为8.7-2.0+2.1×103M& 、年龄为468-14+57 Myr、金属丰度接近太阳丰度的年轻星族成分。另外P2内部也存在一个质量为0.68-0.05+0.07×106M& 的同样的老年成分,和一个质量为5.9-0.9+1.3×103的、年龄为277-18+62 Myr、金属丰度接近太阳丰度的年轻星族成分。我们通过计算得到,仅靠核区内部的星风损失,恒星形成的时标超过宇宙年龄。因此这些年轻恒星不可能由本地恒星星风损失的气体堆积形成,我们认为该年轻星族可能起源于外部气体迁入后坍缩形成,或者在外部形成后迁移进入核区的。我们研究了 HST/COS获得的M31核心星团的远紫外光谱,这也是迄今为止在星系中心pc尺度上获得的第一个远紫外光谱。在1320A-1800A的范围内,我们得出星族由117Myr和518Myr的两个成分组成,该结果与SED测光分析结果相一致。而且我们发现,光谱中的C Ⅳ吸收线(1548.20A/1550.77A)不是由恒星贡献,而是由热星系际介质产生,其等值宽度为(2.14±0.12)A,计算出视线方向上CⅣV的柱密度为3.5×1014cm-2,气体温度为2×105K,并测算出视线方向上的总气体柱密度为～1020cm-2。
[Abstract]:Using images and spectra of the ultraviolet and optical wavelengths of the Hubble Space Telescope (HST), we have studied the core region of M31, which is located within a few seconds of the distance between the M31 black hole and its surrounding stars (that is, the core star cluster). There is a bimodal distribution of surface luminance in which the brighter peak is called P1 and the optically darker peak is called P2. In the ultraviolet band, P2 is more luminous than that of P1. Based on the detection of dynamical information, supermassive black hole M 31 * is found to be located inside P2. In order to study the radiation of M 31 * and the physical properties of the surrounding core cluster, we have done the following. We have made two observations of M 31 * by using the near ultraviolet band image of HST/COS. We have found that the flow rate of (6.9 卤3.0) 脳 10 ~ (-18) erg s ~ (-1) cm-2 A ~ (-1) is different in the ultraviolet band in the measurement aperture of 0.1 angle seconds from the center of M _ (31) *. We extrapolate the luminosity of M31 * in the X-ray band to the ultraviolet band, and obtain the average flux of M31 * is 1.7 脳 10-18 erg s-1 cm2 A-1. The observed flow difference is four times that of the average flow, so it is likely that the difference is due to the luminosity of the central black hole. The core cluster of M31 is analyzed by using the data of 10 images from near ultraviolet band to near infrared band of HST/WFC3. We find that there is an aged star family with a mass of 1.54-0.05 0.08 脳 106M& and a metal abundance of 2.5 times the solar abundance, in addition to a mass of 1.54-0.08 脳 106M-, which is close to the age of the universe. There is also a young star family with a mass of 8.7-2.0 2.1 脳 10 ~ 3M & and a metal abundance of 468-1457 Myr, close to the solar abundance. In addition, within P2 there is the same old age component with a mass of 0.68-0.05 0.07 脳 106M& and a mass of 5.9-0.9 1.3 脳 103, aged 277-18 62 Myr,. A group of young stars with a metallic abundance close to that of the sun. We have calculated that the time scale of star formation exceeds the cosmic age only by the loss of star wind in the nuclear region. Therefore, these young stars can not be formed by the local star wind loss gas accumulation. We believe that the young star family may have originated from the collapse of the external gas migration or migration into the nuclear region after the external formation. We have studied the far ultraviolet spectra of M31 core cluster obtained by HST/COS, which is the first far ultraviolet spectrum obtained so far on the pc scale of the galaxy center. In the range of 1320A-1800A, we obtain that the star family is composed of two components of 117Myr and 518Myr, and the results are in agreement with the results of SED photometry. Furthermore, we find that the absorption line C 鈪，
本文编号：2389081
[Abstract]:Using images and spectra of the ultraviolet and optical wavelengths of the Hubble Space Telescope (HST), we have studied the core region of M31, which is located within a few seconds of the distance between the M31 black hole and its surrounding stars (that is, the core star cluster). There is a bimodal distribution of surface luminance in which the brighter peak is called P1 and the optically darker peak is called P2. In the ultraviolet band, P2 is more luminous than that of P1. Based on the detection of dynamical information, supermassive black hole M 31 * is found to be located inside P2. In order to study the radiation of M 31 * and the physical properties of the surrounding core cluster, we have done the following. We have made two observations of M 31 * by using the near ultraviolet band image of HST/COS. We have found that the flow rate of (6.9 卤3.0) 脳 10 ~ (-18) erg s ~ (-1) cm-2 A ~ (-1) is different in the ultraviolet band in the measurement aperture of 0.1 angle seconds from the center of M _ (31) *. We extrapolate the luminosity of M31 * in the X-ray band to the ultraviolet band, and obtain the average flux of M31 * is 1.7 脳 10-18 erg s-1 cm2 A-1. The observed flow difference is four times that of the average flow, so it is likely that the difference is due to the luminosity of the central black hole. The core cluster of M31 is analyzed by using the data of 10 images from near ultraviolet band to near infrared band of HST/WFC3. We find that there is an aged star family with a mass of 1.54-0.05 0.08 脳 106M& and a metal abundance of 2.5 times the solar abundance, in addition to a mass of 1.54-0.08 脳 106M-, which is close to the age of the universe. There is also a young star family with a mass of 8.7-2.0 2.1 脳 10 ~ 3M & and a metal abundance of 468-1457 Myr, close to the solar abundance. In addition, within P2 there is the same old age component with a mass of 0.68-0.05 0.07 脳 106M& and a mass of 5.9-0.9 1.3 脳 103, aged 277-18 62 Myr,. A group of young stars with a metallic abundance close to that of the sun. We have calculated that the time scale of star formation exceeds the cosmic age only by the loss of star wind in the nuclear region. Therefore, these young stars can not be formed by the local star wind loss gas accumulation. We believe that the young star family may have originated from the collapse of the external gas migration or migration into the nuclear region after the external formation. We have studied the far ultraviolet spectra of M31 core cluster obtained by HST/COS, which is the first far ultraviolet spectrum obtained so far on the pc scale of the galaxy center. In the range of 1320A-1800A, we obtain that the star family is composed of two components of 117Myr and 518Myr, and the results are in agreement with the results of SED photometry. Furthermore, we find that the absorption line C 鈪，
本文编号：2389081
本文链接：https://www.wllwen.com/shoufeilunwen/benkebiyelunwen/2389081.html
