Cosmic 'flashlight' illuminates humongous nebula, reveals mysterious space web
A bright distant quasar illuminating a massive nebula for the first time reveals 'cosmic web' of filaments thought to connect galaxies, say scientists
This deep image shows the nebula (cyan) extending across 2 million light-years that was discovered around the bright quasar UM287 (at the center of the image). The energetic radiation of the quasar makes the surrounding intergalactic gas glow, revealing the morphology and physical properties of a cosmic web filament. The image was obtained at the W. M. Keck Observatory.
Credit: S. Cantalupo, UCSC
An intricate cosmic spider web like pattern has revealed itself for the first time.
Researchers at the University of California, Santa Cruz, discovered a bright distant quasar called UM287 illuminating an enormous nebula consisting of mostly hydrogen and some helium, revealing for the first time part of the network of filaments thought to connect galaxies in a cosmic web, according to a press release by the University of California, Santa Cruz.
A quasar is a supermassive black hole with gas around it that heats up and shines, J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz, who was involved with the study, told the Monitor.
The nebula illuminated by the quasar is massive, extending across 2 million light-years.
"This is a very exceptional object," said Sebastiano Cantalupo, a postdoctoral fellow at UC Santa Cruz and the paper's lead author. "It's huge, at least twice as large as any nebula detected before, and it extends well beyond the galactic environment of the quasar."
Astronomers have long predicted that galaxies are connected through a "cosmic web" of filaments. But this is the first time scientists have actually been able to see and study them by using a high precision telescope and computer simulations.
The study was published in Nature, a science journal.
First of all, researchers used the 10-meter Keck I Telescope at the W. M. Keck Observatory in Hawaii to study the emission of gases. The hydrogen gas illuminated by the quasar emits ultraviolet light known as Lyman alpha radiation, which has a very short wavelength.
The telescope consists of a narrow filter band that allows short-wavelength radiation to pass through it, says Dr. Prochaska.
In addition to spotting faint emissions, the telescope therefore helped in obtaining a very very deep image of the sky, he adds.
"We did not expect to find it," says Prochaska.
The team followed this up by running computer simulations, which suggested that matter in the universe is distributed in a "cosmic web" of filaments, according to the press release.
"We have studied other quasars this way without detecting such extended gas," Dr. Cantalupo said. "The light from the quasar is like a flashlight beam, and in this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow."
The findings speak directly about how the universe was formed and how our galaxy was formed, Prochaska says. It also reveals that there is gas outside our galaxy.