射电星系B2 0258+35的周期性射电辐射和气体供应
Recurrent radio emission and gas supply: the case of the radio galaxy B2 0258+35
摘要：
概述了在射电源B2 0258+35周围发现的一个非常微弱的、弥散的、低表面亮度（平均0.5 \mJybeam，1.4 \mJyarcminsq）的结构，该结构由一个富含HI的早型星系（NGC 1167）托管。由于B2 0258+35是一个年轻的致密陡谱源，新发现的结构可能代表活动星系核活动早期的遗迹。我们接着详细解释了在周期活动星系核活动框架中触发B2 0258+35中关于气体吸积的射电活动的所有可能性。NGC 1167拥有一个非常规则，扩展和巨大的\HI盘，已经被详细研究过。先前对靠近核心的\HI的研究似乎违背了\HI的环核盘作为吸积气体来源的假设。我们认为，从热的X射线晕气体的冷却作为一个可能的替代选项的活动星系核的燃料，在类似的无线电功率B2 0258+35的其他来源的情况下建议。估计的微弱的漫发射的年龄以及目前的吸积率，这是在很好的协议与文献值。如果我们关于吸积机制的假设是正确的，那么在早期星系周围应该更常见类似的大规模遗迹结构，这将有望通过下一代灵敏的低频射电观测得到证实。
英文摘要：
Outlined is the discovery of a very faint, diffuse, low surface-brightness (0.5 \mJybeam, 1.4 \mJyarcminsq on average) structure around the radio source B2 0258+35 hosted by an HI-rich early-type galaxy (NGC 1167). Since B2 0258+35 is a young Compact Steep Spectrum (CSS) source, the newly discovered structure could represent a remnant from an earlier stage of AGN activity. We go on by explaining in detail all the possibilities for triggering the radio activity in B2 0258+35 regarding gas accretion in a recurrent AGN activity framework. NGC 1167 hosts a very regular, extended and massive \HI\ disc that has been studied in great detail. Previous studies of the \HI\ closer to the core seem to go against the assumption of a circum-nuclear disc of \HI\ as the source of the accreting gas. We consider the cooling of gas from the hot, X-ray halo as a possible alternative option for the fueling of the AGN, as suggested in the case of other sources of similar radio power as B2 0258+35. Estimates are given for the age of the faint diffuse emission as well as for the current accretion rate, which are in good agreement with literature values. If our assumptions about the accretion mechanism are correct, similar large-scale, relic-like structures should be more commonly found around early-type galaxies and this will be hopefully confirmed by the next generation of sensitive, low-frequency radio surveys.
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