黑洞的质量被低估了（图）   

新的模拟显示：星系中心的黑洞质量比原以为的要大得多。

Black Holes Have Been Underestimated

Astronomers peering into the heart of one of the largest galaxies in our neighborhood have found that the black hole at its center is two to three times more massive than previously thought, making it the biggest black hole to have ever been measured in the nearby universe.	天文学家们凝视了附近一个最大星系的中心，发现位于这个中心的黑洞比以往认为的要大出2至3倍，因此该黑洞成为近地宇宙中所测量过的最大黑洞。
The result, reported here yeste rday at the semiannual meeting of the American Astronomical Society, suggests that researchers have been severely underestimating the masses of black holes within nearby galaxies. The finding is likely to compel researchers to revise their views about the mechanics of galaxy formation around black holes.	昨天，天文学家们在加州帕萨迪纳市举行的美国天文学会半年会上报道了这个发现。该发现表明，研究人员对附近星系中的黑洞一直存在严重低估的情况。该发现还有可能会迫使研究人员对黑洞周围星系形成的力学原理改变看法。
Researchers figure out the mass of a galaxy by measuring the velocity of the stars orbiting within it and calculating the strength of the gravitational pull required to keep them moving at that speed. These calculations also help scientists determine the mass of black holes, which lie at the center of nearly all galaxies.	通过测量星系内的恒星做环绕运动的速度，并计算保持这个速度所需要的引力，研究人员可以算出星系的质量。这些计算也可以帮助科学家们确定几乎所有星系中心的黑洞质量。
Karl Gebhardt of the University of Texas, Austin, and Jens Thomas of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany applied new computational models to work out the mass of the black hole in the middle of M87, a giant galaxy 50 million light-years away. What the researchers did differently from previous estimations was factor in the dark halo--the invisible sphere of dark matter surrounding the galaxy--which astronomers had believed to be only a relatively small component of the overall mass. Another reason that Gebhardt and other researchers did not attempt to incorporate the dark halo in previous models was the huge amount of computing power needed for the job.	德克萨斯大学奥斯汀分校的卡尔·格布哈特和德国加兴马普学会地外物理研究所的詹斯·托马斯利用计算机模拟技术，计算出星系M87中心的黑洞质量，该星系是位于5,000万光年以外的一个巨大星系。这次与以往的不同之处在于，研究人员重新把暗物质晕这个因素考虑进去。暗物质晕是指星系周围不可见的暗物质圈。以前天文学家们认为暗物质晕只不过是总体质量中相对较小的组成部分。在以前的模拟中，格布哈特及其他研究人员没有将暗物质晕计算在内的另一个原因是，计算暗物质晕时要求计算机具有极大的计算能力。
Running the model on a supercomputer, the team found the mass of M87's black hole to be 6.4 billion times the mass of our sun--two to three times larger than previous estimates. The model provided similar results for four other nearby galaxies, multiplying their black hole masses by factors of 1.5 to 3.	研究小组利用一台超型计算机进行模拟，发现星系M87中黑洞的质量是我们太阳质量的64亿倍，比以前的估计大出2至3倍。对于四个其他附近的星系，该模拟也得出了同样的结果——用原以为的黑洞质量乘以因数1.5到3，才是黑洞的真正质量。
The results, which will be published in The Astrophysical Journal later this summer, "caught us off guard," says Gebhardt. "It looks like we've been systematically underestimating the mass of black holes."	今年夏末，这些研究结果将要发表在《天体物理学杂志》上。“这些结果是我们始料不及的，”格布哈特说，“我们好象一直从整个系统上低估了黑洞的质量。”
Because the gravity of the black hole influences the behavior of the galaxy around it, a doubling or tripling of the black hole mass will alter the picture of how galactic material might be swirling around it, says Tod Lauer, an astronomer at the National Optical Astronomy Observatory in Tucson, Arizona. And that influences the way galaxies grow and change.	亚利桑那州图森市美国国家光学天文台的天文学家托德·劳尔称，由于黑洞的引力影响星系的活动，两倍或三倍的黑洞质量将会改变天文学家们对黑洞周围星系物质盘绕方式的印象。这同样也会影响到星系的发展和变化。