2024年5月30日发(作者：)

A new kind of cosmic flash may reveal something never seen before: the birth of a black

hole. When a massive star exhausts its fuel, it collapses under its own gravity and produces

a black hole, an object so dense that not even light can escape its gravitational grip.

According to a new analysis by an astrophysicist（天体物理学家） at the California Institute

of Technology (Caltech), just before the black hole forms, the dying star may generate a

distinct burst of light that will allow astronomers to witness the birth of a new black hole for

the first time.

Tony Piro, a postdoctoral scholar at Caltech, describes this signature light burst in a paper

published in the May 1 issue of the Astrophysical Journal Letters. While some dying stars

that result in black holes explode as gamma-ray bursts, which are among the most

energetic phenomena in the universe, those cases are rare, requiring exotic circumstances,

Piro explains. "We don't think most run-of-the-mill black holes are created that way." In

most cases, according to one hypothesis, a dying star produces a black hole without a bang

or a flash: the star would seemingly vanish from the sky -- an event dubbed an unnova.

"You don't see a burst," he says. "You see a disappearance."

But, Piro hypothesizes, that may not be the case. "Maybe they're not as boring as we

thought," he says.

According to well-established theory, when a massive star dies, its core collapses under its

own weight. As it collapses, the protons and electrons that make up the core merge and

produce neutrons. For a few seconds -- before it ultimately collapses into a black hole -- the

core becomes an extremely dense object called a neutron star, which is as dense as the sun

would be if squeezed into a sphere with a radius of about 10 kilometers (roughly 6 miles).

This collapsing process also creates neutrinos, which are particles that zip through almost

all matter at nearly the speed of light. As the neutrinos stream out from the core, they carry

away a lot of energy -- representing about a tenth of the sun's mass (since energy and

mass are equivalent, per E = mc2).

According to a little-known paper written in 1980 by Dmitry Nadezhin of the Alikhanov

Institute for Theoretical and Experimental Physics in Russia, this rapid loss of mass means

that the gravitational strength of the dying star's core would abruptly drop. When that

happens, the outer gaseous（气态的） layers -- mainly hydrogen -- still surrounding the core

would rush outward, generating a shock wave that would hurtle through the outer layers at

about 1,000 kilometers per second (more than 2 million miles per hour).

Using computer simulations, two astronomers at UC Santa Cruz, Elizabeth Lovegrove and

Stan Woosley, recently found that when the shock wave strikes the outer surface of the

gaseous layers, it would heat the gas at the surface, producing a glow that would shine for

about a year -- a potentially promising signal of a black-hole birth. Although about a million

times brighter than the sun, this glow would be relatively dim compared to other stars. "It

would be hard to see, even in galaxies that are relatively close to us," says Piro.

But now Piro says he has found a more promising signal. In his new study, he examines in

more detail what might happen at the moment when the shock wave hits the star's surface,

and he calculates that the impact itself would make a flash 10 to 100 times brighter than

the glow predicted by Lovegrove and Woosley. "That flash is going to be very bright, and it

gives us the best chance for actually observing that this event occurred," Piro explains.

"This is what you really want to look for."

一种新的宇宙闪光可能会发现以前从未见过的东西：一个黑洞的诞生。当一颗大质量恒星耗尽燃料，它

在自身重力作用下崩溃，并产生一个黑洞，如此密集，连光都无法逃脱它的引力握对象。根据一项新的

分析（天体物理学家）在加州理工学院（加州理工学院）的天体物理学家，就在黑洞形式，垂死的恒星

可能会产生明显的突发光将使天文学家见证诞生的第一次一个新的黑洞。

在加州理工学院博士后学者托尼·皮罗，在5月1日发行的“天体物理学杂志快报”发表了一篇论文，描述

了这个签名的光突发。虽然一些垂死恒星伽马射线暴在宇宙中最有活力的现象，这是导致黑洞爆炸，那

些案件是罕见的，需要异国情调的情况下，皮罗解释。“我们不认为大多数运行的磨黑洞创造的方式。” 在

大多数情况下，根据一个假设，一个垂死恒星产生一个黑洞，没有爆炸或闪光灯：明星似乎从天空消失 -

事件配成unnova。“你看不到了一阵，”他说。“你可以看到消失。”

但是，皮罗推测，这可能不是这种情况。“也许他们不是因为无聊，因为我们认为，”他说。

根据行之有效的理论，当一个大质量恒星死亡坍塌根据其自身的重量，它的核心。它倒塌，质子和电子

组成的核心合并，产生中子。几秒钟 - 之前，它最终坍缩成一个黑洞的核心 - 成为一个极其致密的天

体，称为中子星，这是密集的太阳将如果挤进一个球体，半径约10公里（大约6英里）。这一崩溃过

程中产生的中微子，这是在近光速的速度通过几乎所有的物质粒子压缩。由于中微子流从核心，他们带

走了大量的精力 - 太阳的质量（约占十分之一，因为能量和质量是等价的，每E = MC2）。

根据一个鲜为人知的论文写于1980年由梅德Nadezhin的Alikhanov的理论和实验物理研究所在俄罗

斯，这种快速的质量损失是指 垂死恒星的核心引力强度会突然下降。当这种情况发生时，外层的气体（气

态的）层-主要是氢气-仍围绕核心向外冲，产生的冲击波将通过外层每秒约1000公里（超过200万英

里的速度呼啸而过小时）。

利用计算机模拟，在加州大学圣克鲁兹分校，伊丽莎白Lovegrove设计和斯坦伍斯利，两位天文学家最

近发现，当冲击波撞击的外表面的气态层，它会加热气体在表面上，产生辉光照耀约一年 - 一个黑洞诞

生的一个很有潜力的信号。虽然比太阳亮约一百万次，这光芒将其他恒星相比，比较昏暗。“这将是很难

看，甚至都比较接近我们的星系中，”皮罗说。

但现在的皮罗说，他已经找到了更有前途的信号。在他的新的研究中，他探讨更多的细节什么可能发生

的那一刻时的冲击波击中恒星的表面，他计算，影响本身就使闪光灯的10至100倍明亮比辉光

Lovegrove设计和伍斯利预测。“Flash是将是非常光明的，它为我们提供了最好的机会，实际观察，

这一事件发生后，”皮罗解释。“ “这是你真正想要的去寻找。”