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天文学家探测到距离地球数十亿光年的无线电“心跳”

Astronomers detect a radio ‘heartbeat’ billions of light-years from Earth

Astronomers at MIT and elsewhere have detected a strange and persistent radio signal from a far-off galaxy that appears to be flashing with surprising regularity.

麻省理工学院和其他地方的天文学家检测到来自遥远星系的奇怪且持续的无线电信号,该信号似乎以惊人的规律性闪烁。

The signal is classified as a fast radio burst, or FRB — an intensely strong burst of radio waves of unknown astrophysical origin, that typically lasts for a few milliseconds at most. However, this new signal persists for up to three seconds, about 1,000 times longer than the average FRB. Within this window, the team detected bursts of radio waves that repeat every 0.2 seconds in a clear periodic pattern, similar to a beating heart.

该信号被归类为快速无线电波爆发(FRB)——一种来自未知天体物理的强烈无线电波爆发,通常最多持续几毫秒。然而,这种新信号持续时间长达三秒,约为FRB平均值的1000倍。在这个窗口内,研究小组检测到无线电波爆发,以清晰的周期模式每0.2秒重复一次,类似于心跳。

The researchers have labeled the signal FRB 20191221A, and it is currently the longest-lasting FRB, with the clearest periodic pattern, detected to date.

研究人员已将信号FRB标记为20191221A,它是目前检测到的持续时间最长的FRB,具有最清晰的周期模式。

The source of the signal lies in a distant galaxy, several billion light-years from Earth. Exactly what that source might be remains a mystery, though astronomers suspect the signal could emanate from either a radio pulsar or a magnetar, both of which are types of neutron stars — extremely dense, rapidly spinning collapsed cores of giant stars.

信号源位于一个距离地球数十亿光年的遥远星系。确切的信号源可能是什么仍然是个谜,尽管天文学家怀疑信号可能来自射电脉冲星或磁星,这两种类型的中子星都是密度极高、快速旋转的巨星坍缩核心。

“There are not many things in the universe that emit strictly periodic signals,” says Daniele Michilli, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beamed emission similar to a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids.”

麻省理工学院卡夫利天体物理与空间研究所的博士后丹尼尔·米奇利说:“宇宙中没有多少东西会发出严格的周期性信号。”。“我们在银河系中所知道的例子是射电脉冲星和磁星,它们旋转并产生类似灯塔的光束发射。我们认为这种新信号可能是一个类固醇磁星或脉冲星。”

The team hopes to detect more periodic signals from this source, which could then be used as an astrophysical clock. For instance, the frequency of the bursts, and how they change as the source moves away from Earth, could be used to measure the rate at which the universe is expanding.

该团队希望从这个来源探测到更多的周期性信号,然后将其用作天体物理时钟。例如,爆发的频率,以及当放射源离开地球时它们如何变化,可以用来测量宇宙膨胀的速度。

The discovery is reported today in the journal Nature, and is authored by members of the CHIME/FRB Collaboration, including MIT co-authors Calvin Leung, Juan Mena-Parra, Kaitlyn Shin, and Kiyoshi Masui at MIT, along with Michilli, who led the discovery first as a researcher at McGill University, and then as a postdoc at MIT.

这一发现今天发表在《自然》杂志上,由CHIME/FRB合作的成员撰写,包括麻省理工学院的合著者梁凯文、胡安·梅娜·帕拉、申凯琳和清水正吉,以及米奇利,他首先在麦吉尔大学作为研究员领导了这一发现,然后在麻省理工学院担任博士后。

“Boom, boom, boom”

“砰,砰,砰”

Since the first FRB was discovered in 2007, hundreds of similar radio flashes have been detected across the universe, most recently by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, an interferometric radio telescope consisting of four large parabolic reflectors that is located at the Dominion Radio Astrophysical Observatory in British Columbia, Canada.

自2007年发现第一个FRB以来,在整个宇宙中检测到数百个类似的射电闪光,最近一次是由加拿大氢强度映射实验(CHIME)检测到的,CHIME是一种干涉射电望远镜,由四个大型抛物面反射器组成,位于加拿大不列颠哥伦比亚省的Dominion射电天体物理天文台。

CHIME continuously observes the sky as the Earth rotates, and is designed to pick up radio waves emitted by hydrogen in the very earliest stages of the universe. The telescope also happens to be sensitive to fast radio bursts, and since it began observing the sky in 2018, CHIME has detected hundreds of FRBs emanating from different parts of the sky.

CHIME在地球自转时不断观察天空,其设计目的是接收宇宙最早期阶段氢发射的无线电波。该望远镜恰好对快速射电爆发也很敏感,自2018年开始观测天空以来,CHIME已经检测到数百个FRB从天空的不同部分发出。

The vast majority of FRBs observed to date are one-offs — ultrabright bursts of radio waves that last for a few milliseconds before blinking off. Recently, researchers discovered the first periodic FRB that appeared to emit a regular pattern of radio waves. This signal consisted of a four-day window of random bursts that then repeated every 16 days. This 16-day cycle indicated a periodic pattern of activity, though the signal of the actual radio bursts was random rather than periodic.

到目前为止,观察到的绝大多数FRB都是一次性的,即持续数毫秒后才闪烁的超亮无线电波爆发。最近,研究人员发现了第一个周期性FRB,它似乎发射出规则模式的无线电波。该信号由四天的随机爆发窗口组成,然后每16天重复一次。这16天的周期表明了活动的周期性模式,尽管实际射电爆发的信号是随机的,而不是周期性的。

On Dec. 21, 2019, CHIME picked up a signal of a potential FRB, which immediately drew the attention of Michilli, who was scanning the incoming data.

2019年12月21日,CHIME收到了一个潜在FRB的信号,这立即引起了正在扫描传入数据的米奇利的注意。

“It was unusual,” he recalls. “Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom — like a heartbeat. This is the first time the signal itself is periodic.”

“这很不寻常,”他回忆道。“它不仅非常长,持续约三秒,而且有非常精确的周期性峰值,发出一秒中的每一分之一——砰,砰,砰——就像心跳一样。这是信号本身第一次具有周期性。”

Read More at ScienceDailey.com

更多信息请访问ScienceDailey.com

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