标题： 本地宇宙中棒状星系和黑洞的持续形成：来自GALEX的新见解 显示英文标题

标题： Ongoing Formation of Bulges and Black Holes in the Local Universe: New Insights from GALEX

摘要： 我们分析了一个体积受限的大量核球主导星系样本，数据来自斯隆数字天空勘测和银河系演化探测器（GALEX）卫星。这些星系的中心速度弥散大于100 km/s，并且恒星表面质量密度高于星系从活跃恒星形成系统过渡到被动系统的值。该样本限制在红移0.03<z<0.07范围内。在这些距离上，SDSS光谱采样了星系核球主导的中心区域的光。GALEX NUV数据对这些系统中低的全局恒星形成率具有高灵敏度。我们所研究的核球主导星系在NUV-r颜色上的离散度远大于在光学g-r颜色上的离散度。几乎所有NUV-r颜色较蓝的星系都是活动星系核（AGN）。GALEX图像和SDSS颜色剖面都表明，过量的紫外光与一个扩展的盘有关。我们发现，外区呈红色的星系几乎从不拥有年轻的核球或强烈的AGN。外区呈蓝色的星系的核球和黑洞在年龄和吸积率方面范围很广。拥有年轻核球和强烈吸积黑洞的星系几乎总是拥有蓝色外盘。我们提出的场景是，构建核球和黑洞的气体来源是盘中的低质量冷气体储库。这种气体的存在是核球和黑洞增长的必要条件，但不是充分条件。必须有一种机制以时间变化的方式将这种气体向内输送。当盘中的气体转化为恒星时，星系会变红，但进一步的气体流入可以使它们重新进入蓝色的NUV-r序列。（简写） 显示英文摘要

摘要： We analyze a volume-limited sample of massive bulge-dominated galaxies with data from both the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX) satellite. The galaxies have central velocity dispersions greater than 100 km/s and stellar surface mass densities that lie above the value where galaxies transition from actively star forming to passive systems. The sample is limited to redshifts 0.03<z<0.07. At these distances, the SDSS spectra sample the light from the bulge-dominated central regions of the galaxies. The GALEX NUV data provide high sensitivity to low rates of global star formation in these systems. Our sample of bulge-dominated galaxies exhibits a much larger dispersion in NUV-r colour than in optical g-r colour. Nearly all of the galaxies with bluer NUV-r colours are AGN. Both GALEX images and SDSS colour profiles demonstrate that the excess UV light is associated with an extended disk. We find that galaxies with red outer regions almost never have a young bulge or a strong AGN. Galaxies with blue outer regions have bulges and black holes that span a wide range in age and accretion rate. Galaxies with young bulges and strongly accreting black holes almost always have blue outer disks. Our suggested scenario is one in which the source of gas that builds the bulge and black hole is a low mass reservoir of cold gas in the disk.The presence of this gas is a necessary, but not sufficient condition for bulge and black hole growth. Some mechanism must transport this gas inwards in a time variable way. As the gas in the disk is converted into stars, the galaxies will turn red, but further gas infall can bring them back into the blue NUV-r sequence.(Abridged)