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标题：UVIT observations of the star-forming ring in NGC 7252: Evidence of possible AGN feedback suppressing central star formation
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作者：K. George ; P. Joseph ; C. Mondal 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：613
DOI：10.1051/0004-6361/201833232
语种：English
出版社：EDP Sciences
摘要：Context.Some post-merger galaxies are known to undergo a starburst phase that quickly depletes the gas reservoir and turns it into a red-sequence galaxy, though the details are still unclear.Aims.Here we explore the pattern of recent star formation in the central region of the post-merger galaxy NGC 7252 using high-resolution ultraviolet (UV) images from the UVIT on ASTROSAT.Methods.The UVIT images with 1.2 and 1.4 arcsec resolution in the FUV and NUV are used to construct a FUV-NUV colour map of the central region.Results.The FUV-NUV pixel colour map for this canonical post-merger galaxy reveals a blue circumnuclear ring of diameter ~10′′ (3.2 kpc) with bluer patches located over the ring. Based on a comparison to single stellar population models, we show that the ring is comprised of stellar populations with ages ≲300 Myr, with embedded star-forming clumps of younger age (≲150Myr).Conclusions.The suppressed star formation in the central region, along with the recent finding of a large amount of ionised gas, leads us to speculate that this ring may be connected to past feedback from a central super-massive black hole that has ionised the hydrogen gas in the central ~4′′ ~1.3 kpc.
关键词：Key wordsengalaxies: elliptical and lenticular, cDgalaxies: evolutiongalaxies: formationgalaxies: nucleigalaxies: star formationultraviolet: galaxies