来自GTC/MEGARA积分场光谱数据的Mrk 1498重启活动星系核活动的线索
Clues of the restarting active galactic nucleus activity of Mrk 1498 from GTC/MEGARA integral field spectroscopy data
AI总结：
本研究利用GTC/MEGARA积分场光谱分析Mrk 1498的电离气体特征，提出其射电AGN存在两个主要活动期，光学团块对应两次活动间闪烁AGN驱动的化石外流，为AGN重启活动提供了观测线索。
摘要：
部分在X射线波段筛选出的、具有活动星系核（AGN）的巨射电星系表现出核活动重启的迹象。这类特殊天体中的一个是Mrk 1498，它是一个巨型低频双射电源，在[OIII]谱线中表现出延展辐射，这种辐射很可能与该星系的核活动历史相关。我们探究这种泡状辐射是否能够追踪来自当前或过去AGN活动的外流。我们利用MEGARA/GTC的中分辨率光谱（分辨率R≈10000）数据，通过对[OIII]和Hβ谱线特征进行三个运动学分量的建模，得到了电离气体的运动学性质和流量。所有分量整体呈现出从蓝移到红移的速度模式，峰间速度相近但速度弥散不同。在距星系中心2.3千秒差距（kpc）处，我们发现了一个速度高达100千米/秒、速度弥散高达170千米/秒的团块，其空间位置与射电喷流的方向重合。观测到的[OIII]/Hβ线比表明，几乎所有区域都可能存在来自AGN或激波的电离作用。哈勃空间望远镜（HST）图像中在kpc尺度上可见的团块结构具有最低的log[OIII]/Hβ值，这很可能与AGN的光致电离无关。结合光学和射电活动，我们提出了Mrk 1498射电AGN生命周期中存在两种不同电离气体特征的演化图景。射电辐射表明至少存在两个主要的射电活动期：一个是在百万秒差距（Mpc）尺度上的古老活动期（在100百万年的时间跨度内形成），另一个是来自核心的新活动期（始于2000多年前）。在光学波段，我们观测到的团块和亮斑很可能与化石外流相关，后者很可能由两次主要射电活动期之间可能发生的、AGN活动的闪烁式过往事件所驱动。
英文摘要：
Some giant radio galaxies selected at X-rays with an AGN show signs of a restarted nuclear activity. One object in this peculiar class is Mrk1498, a giant low-frequency double radio source that shows extended emission in [OIII]. This emission is likely related to the history of the nuclear activity of the galaxy. We investigate whether this bubble-like emission might trace an outflow from either present or past AGN activity. Using MEGARA/GTC, medium-resolution spectroscopy (R 10000) data, we obtained the kinematics and fluxes of the ionised gas from modelling the [OIII] and Hbeta features.with three kinematic components. All the components show an overall blue to red velocity pattern, with similar peak-to-peak velocities but a different velocity dispersion. At a galactocentric distance of 2.3 kpc, we found a blob with a velocity up to 100km/s, and a high velocity dispersion (170km/s) that is spatially coincident with the direction of the radio jet. The observed [OIII]/Hbeta line ratio indicates possible ionisation from AGN or shocks nearly everywhere. The clumpy structure visibile in HST images at kpc scales show the lowest values of log[OIII]/Hbeta , which is likely not related to the photoionisation by the AGN. Taking optical and radio activity into account, we propose a scenario of two different ionised gas features over the radio AGN lifecycle of Mrk 1498. The radio emission suggests at least two main radio activity episodes: an old episode at Mpc scales (formed during a time span of 100Myr), and a new episode from the core (>2000yr ago). At optical wavelengths, we observe clumps and a blob that are likely associated with fossil outflow. The latter is likely powered by past episodes of the flickering AGN activity that may have occurred between the two main radio phases.
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