主要内容
NWACC Alumna and Team Observe 宇宙事件 in Both Gravitational Waves and Light for the First Time
蕾切尔·汉伯格只是宇宙大事件的一小部分。
Rachel, a 2014 正规博彩平台 (NWACC) alumna, was on a research team analyzing data in a significant scientific discovery in 2017. Two neutron stars collided some 130 million light years away, and researchers were able to observe gravitational waves and a gamma-ray burst from the same event. Put another way, this was the first time a cosmic event was observed in 包括引力波和光。
在科学界，这一发展是巨大的。 Scientific American magazine
identified it as one of its 年度十大科学故事.
A graduate student at the University of Alabama in Huntsville, Rachel had not just
a front-row seat to the discovery, but played a part. Rachel is a research assistant
working with the Fermi Gamma-ray Burst Monitor (GBM). The Fermi GBM was launched in
2008 and is the NASA instrument that detected the gamma-ray burst from the binary
neutron star merger. “This is most exciting discovery of the Fermi mission,” Rachel
says, “and I can’t believe I get to be a part of it all. 这真是难以置信。”
她撰写了两篇与该事件有关的学术论文。 According to a news release from the University of Alabama in Huntsville, she developed some of the software used in the analysis of data. She is one of the authors of “An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A.”
Recently, the Fermi Gamma-ray Burst Monitor team was selected as the recipient of the Rossi Prize awarded annually in honor of Bruno Rossi “for a significant contribution to High Energy Astrophysics, with particular emphasis on recent, original work.” More about that honor can found in this 最近的UAH新闻发布.
NWACC影响
瑞秋在NWACC的经历塑造了她对今天研究工作的想法。
She came to NWACC after having been home-schooled, and the smaller class sizes and more individualized attention appealed to her. “When I started thinking about college, I wanted to get a bachelor’s degree,” she recalls. “But I was concerned that going to a big university would be a lot. 我觉得NWACC会是一个很好的起点。 班级规模会更小。 I could talk to my classmates and my professors and really feel comfortable in that environment.”
她发现NWACC很适合她。 “It’s very easy to find out what’s here and just to be involved,” she says.
Rachel participated in 服务学习 projects and in the 荣誉项目. “We were working with a community service program about raising awareness about the Marshall Islands,” she recalls. “我很喜欢。” In 服务学习, she appreciated the flexibility and the ability to tailor projects to what the students believed would meet the needs or goals. “你得到的是指导方针，而不是细节。 You can work within that framework and really bring out what you find interesting while bringing awareness to important issues.”
荣誉项目的教员激励了她。 “Especially in the 荣誉 classes, my professors really pushed you to think creatively,” she says.
她对其他教员也给予了很高的评价。 Valor Pickett, a history professor was discussing the slave trade and, to add a connection with the senses, turned out the lights while describing the conditions aboard ships transporting slaves to the New World.
Her first English class was under the instruction of Jim Laughton, and she recalls investing considerable time trying to make her papers top-notch. “He wanted us to write well,” she says. “我喜欢那门课，我在那门课上非常努力。”
她还记得跟随特雷西·沃恩学习微积分I和微积分II。 “I really loved her classes because she taught it in a way that made you feel like everyone can understand this, you just need to work at it,” she says.
Rachel completed an 理学副学士 at NWACC and transferred to the University of Arkansas, where she earned a Bachelor of Science in Physics. She’s now a master’s student at UA-Huntsville, and she hopes to enter doctoral studies later this year.
在她目前的角色，雷切尔回忆起她在NWACC的时间，并试图应用经验教训。 For example, she says that the ability to write clearly is important to scientific writing. “The best thing about being in science is that you’re going to convey the truth and in a way that’s very fact-based,” she says. “When I write things, I remember a lot of what my English professors were saying and try to make sure I convey things clearly by using correct grammar.”
While people may complain about commas, Rachel says she knows it’s important to consider the proper usage when writing. “I heard about another research group, a big collaboration, spending maybe a week or two debating where a comma should go in a sentence because the comma changed the meaning of the sentence,” she explains.
That value for precision that NWACC English faculty instilled in Rachel serves her well in her current studies.
Today, she blends the precision of science with the passion for discovering how things work in the universe. At times, she’s clearly elated at being a part of the most recent discoveries in astrophysics.
发现背后的科学
引力波和伽马射线暴并不是每个人晚餐时的正常话题。 瑞秋有能力帮助非天体物理学家理解这一切。
让我们从引力波开始。 NASA defines a gravitational wave as an invisible (yet incredibly fast) ripple in space.
Rachel explains it this way: “When you have any type of matter that’s moving, it’s disturbing space. 你可以想象一条鱼在水里游动。 As it’s swimming around, you get these waves coming from the fish moving. In a similar kind of way, when you have mass or matter moving in space, it’s giving off these waves.”
Albert Einstein predicted the existence of gravitational waves in 1915 in his general theory of relativity. Confirmation of Einstein’s prediction had come indirectly after two astronomers in Puerto Rico discovered a binary pulsar in 1974 and over years observed that the stars were getting closer together at the rate predicted by general relativity. In this century, three large detectors — two in the United States known as LIGO (Laser Interferometer Gravitational-Wave Observatory) and one in Italy known as Virgo — have come online and started physically sensing distortions in spacetime.
Previous detection of gravitational waves from LIGO and Virgo had only come from black holes and not two neutron stars colliding. According to space.com, neutron stars are created when giant stars die in supernovas and their cores collapse.
雷切尔是这样解释的：“中子星非常古老，已经到了生命的尽头。 在某个时候，中子星是一颗巨大的气态恒星。 Eventually it ran out of gas or fuel. 在那一点上，恒星爆炸了，留下了一个中子星核心。”
中子星质量很大。 They’re described as the size of a city, but having more mass than the sun. “你把所有的物质都塞进了这个小区域。 它非常致密，而且非常重，”她说。
这两颗中子星绕着彼此旋转。 “As they’re going around, they’re emitting these gravitational waves because they’re moving through space,” Rachel notes. “As they emit the gravitational waves, they lose energy and get closer together. Eventually, their gravitational pull is strong enough to start ripping each other apart. 所有这些被撕裂的物质然后发生碰撞和爆炸。”
Some of the matter from the explosion is funneled into two jets that spew all of this matter and photons (light), Rachel says. “It’s called a gamma ray burst because the majority of the light in that jet is in gamma rays, which is the most energetic form of light.”
瑞秋的经历
这是8月17日的一条短信，提醒瑞秋发生了不寻常的事情。
瑞秋回忆说：“那是凌晨，大概7点半。” “I got a text from a graduate student in LIGO that said, ‘We’re about to send out a notice to the astrophysics community. 我们看到了中子星和中子星的合并。”
雷切尔解释说，这是第一次观察到这种现象。 Previously, gravitational waves had come from black holes colliding. “This was the first time they had seen gravitational waves from neutron stars, so number one, this was a big thing,” she says. “我们都在等这一刻。”
瑞秋在描述接下来的部分时仍然很兴奋。 “His next sentence — ‘and there was a gamma-ray burst two seconds later’ — made my heart start beating wildly,” she says. “My body began to physically shake because I knew if this gamma-ray burst had come from the same system that caused the gravitational waves, for us in astrophysics, this would be big.”
她解释说，伽马射线暴经常被探测到。 “我们每天大约收到一份。 We see them all the time.” But scientists were not positive what produced this particular type of gamma-ray burst.
伽马射线暴有长短两种形式。 “We knew that the long ones came from stars that went supernova,” Rachel says. “We didn’t know where these short ones came from. We thought that they came from these types of [neutron star merger] systems, but we had never seen it, observed it, so we didn’t know.”
她说，这一事件意义重大，原因有几个。 “It’s confirmation that these short bursts come neutron star-neutron star mergers,” she notes. “Like I said, before we didn’t know, and now we know. 我们知道这些东西是从正规博彩平台来的。 They’re not completely mysterious in that sense anymore.”
“I think it’s also important because there were so many people who worked on this one event,” she says. “Every single continent had a detector that contributed to this, so literally it was a worldwide effort.”
Her team working with the Fermi GBM was only one group of many making observations related to the event. 这里有从事引力波探测的研究人员。 Optical astronomers pointing their telescopes to that region of the sky saw what’s called a kilonova explosion that was first very blue and then eventually went red. View a 视频 combining real images and artists’ illustrations.
Each specific group of researchers will be focused on their own area, “but when you bring it all together, that’s when you really start to learn things about physics and about the universe,” Rachel says. “我认为这非常重要，而且很棒。 令人惊讶的是，我们都能做到这一点，在这个时代也是如此。 A hundred years ago we didn’t have the technology to detect gravitational waves or communicate the information instantly. 即使在50、25年前，我们也做不到这一点。 This is a very special time.”
瑞秋说，她很荣幸能参与这个发现的时刻。 “I can’t
believe that I’m here and working on this,” she says. “People have been working on
this for decades. Einstein predicted gravitational waves a hundred years ago, and
we’re just now detecting them. People today have been spending their whole careers
to set up these pipelines so that when these things happen, we can automatically just
go ahead and do the research. We don’t have to wait and figure out how to make this
thing work. To be a part of that as a grad student…, to contribute my little piece,
is just great.”
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