外语教育网
您的位置:外语教育网 > 行业英语 > 天文学英语 > 相关阅读 正文
  • 站内搜索:

黑洞的能量效率惊人

2007-03-09 17:59

  Astronomers have discovered that, deep inside the biggest and brightest galaxies in the universe, jets are spewing particles from around black holes in an incredibly energy-efficient manner. If an automobile engine worked as well as one of these monsters, it could go more than a billion miles on a gallon of gas.

  The surprise is these high-mileage black holes aren't quasars, which are considered the most energetic and efficient bodies in the universe at converting matter to energy . Instead, astronomers have discovered, they are relatively old and quiet supermassive black holes that somehow can maintain similar efficiencies while expelling much less energy.

  The astronomers used data from the Chandra X-ray Observatory to study nine supermassive black holes populating very large elliptical galaxies. In all cases, they found the areas around the black holes to be dim in visible light but quite bright in x-ray wavelengths. For the nine objects studied, they calculated that the black holes could convert up to 2.5% of the infalling gas and dust to energy——not quite as good as a quasar, which can average 5% or more, but still about 25 times better than the best nuclear power reactors.

  The team also found that the jets produced by the supermassives are streaming outward at incredible speeds——in some cases 95% of the speed of light. "The energy in these jets is absolutely huge," says lead researcher Steven Allen of Stanford University in Palo Alto, California, "about a trillion, trillion, trillion watts." The findings were announced during a media teleconference today and will be published in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.

  The question is what process converts the energy from the gas streaming in toward the black holes to the enormous energy in the jets. So far, there is only speculation, says co-author Christopher Reynolds of the University of Maryland, College Park. One idea is that the rotational energy of the supermassives powers the engine.

  "We already knew quasars were enormously efficient at making light," says Kimberly Weaver, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Now we know black holes in elliptical galaxies are also as efficient at making x-rays." This also could explain why there are few young stars in these galaxies: When the jets collide with the surrounding interstellar gas, they heat it to the point where it cannot condense into new stars.

  "Just as with cars, it's critical to know the fuel efficiency of black holes," Allen adds. "Without this information, we cannot figure out what is going on under the hood, so to speak, or what the engine can do."

相关热词:天文学 英语 相关 阅读
行业英语辅导课程
李 健协和医科大学医学博士,美国国立卫生研究院博士后……详情>>
李健:医学英语网上辅导名师
高 云澳大利亚注册会计师协会会员,会计专业硕士……详情>>
高云:财会英语网上辅导名师
李文沛中国政法大学博士,师从著名法学家周忠海教授……详情>>
李文沛:法律英语网上辅导名师

  1、凡本网注明 “来源:外语教育网”的所有作品,版权均属外语教育网所有,未经本网授权不得转载、链接、转贴或以其他方式使用;已经本网授权的,应在授权范围内使用,且必须注明“来源:外语教育网”。违反上述声明者,本网将追究其法律责任。
  2、本网部分资料为网上搜集转载,均尽力标明作者和出处。对于本网刊载作品涉及版权等问题的,请作者与本网站联系,本网站核实确认后会尽快予以处理。本网转载之作品,并不意味着认同该作品的观点或真实性。如其他媒体、网站或个人转载使用,请与著作权人联系,并自负法律责任。
  3、联系方式
  编辑信箱:for68@chinaacc.com
  电话:010-82319999-2371