arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1002.3156astro-ph.CO
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星爆-活动星系核连接的计时

Timing the starburst-AGN connection

Vivienne Wild, Timothy Heckman, Stephane Charlot

摘要:

位于星系中心的超大质量黑洞的质量与容纳它们的星系凸起的质量密切相关。这种观察到的相关性意味着一种联合生长的机制,但负责的确切物理过程是一个有争议的问题。在这里,我们报告的增长黑洞在400个地方星系的凸起,经历了一个强大的恒星形成的爆发在过去的600万年。我们样本中的黑洞的典型质量为10^6.5-10^7.5太阳质量,活动核的辐射热光度为10^42- 10^44 erg/s。我们结合恒星的连续性指数与H-α光度测量的衰减时标~ 300 Myr的恒星形成后,恒星暴的下降。在恒星爆发后的第一个6亿年,我们样本中的黑洞的质量平均增加了5%,形成的恒星的总质量大约是吸积到黑洞上的总质量的1000倍。这个比例与在现今的膨胀中观察到的恒星与黑洞质量的比例相似。我们发现,物质在黑洞上的平均吸积速率在恒星暴增开始后大约2.5亿年急剧上升。我们表明,我们的研究结果是一致的一个简单的模型,其中0.5%的质量损失的中等质量的恒星在隆起的吸积的黑洞,但抑制黑洞增长的效率在早期的时候可能是由超新星反馈,这是在早期较强。我们认为这幅图可能更普遍地适用于黑洞的生长,并有助于解释膨胀和黑洞质量之间的强相关性。

英文摘要:

The mass of super massive black holes at the centre of galaxies is tightly correlated with the mass of the galaxy bulges which host them. This observed correlation implies a mechanism of joint growth, but the precise physical processes responsible are a matter of some debate. Here we report on the growth of black holes in 400 local galactic bulges which have experienced a strong burst of star formation in the past 600Myr. The black holes in our sample have typical masses of 10^6.5-10^7.5 solar masses, and the active nuclei have bolometric luminosities of order 10^42-10^44erg/s. We combine stellar continuum indices with H-alpha luminosities to measure a decay timescale of ~300Myr for the decline in star formation after a starburst. During the first 600Myr after a starburst, the black holes in our sample increase their mass by on-average 5% and the total mass of stars formed is about 1000 times the total mass accreted onto the black hole. This ratio is similar to the ratio of stellar to black hole mass observed in present-day bulges. We find that the average rate of accretion of matter onto the black hole rises steeply roughly 250Myr after the onset of the starburst. We show that our results are consistent with a simple model in which 0.5% of the mass lost by intermediate mass stars in the bulge is accreted by the black hole, but with a suppression in the efficiency of black hole growth at early times plausibly caused by supernova feedback, which is stronger at earlier times. We suggest this picture may be more generally applicable to black hole growth, and could help explain the strong correlation between bulge and black hole mass.

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