Unraveling the Mystery of the Phoenix Galaxy Cluster: Recent research has shed light on the extreme cooling process within the Phoenix galaxy cluster, revealing a surprising rate of star formation in its central galaxy.
The Phoenix galaxy cluster has long been an enigma to astronomers. Located 5.8 billion light-years from ‘Earth’ , this massive collection of galaxies is expected to be ‘red and dead,’ meaning it should no longer be forming stars. However, observations have revealed that the core of the Phoenix cluster is surprisingly bright, with its central galaxy churning out stars at an extremely vigorous rate.
The Puzzle of Extreme Cooling
Astronomers had previously detected pockets of both ultrahot gas, with temperatures reaching 1 million degrees Fahrenheit, and regions of extremely cold gas, just 10 kelvins above absolute zero. The presence of very hot gas is not surprising, as most massive galaxies host black holes that emit jets of energetic particles. However, the presence of ultracold gas in an older galaxy like the Phoenix cluster raised a puzzle: where did this cold gas come from?
Detecting Warm Gas
To answer this question, researchers at MIT and elsewhere used NASA‘s ‘James Webb Space Telescope (JWST)’ to observe the Phoenix cluster. They looked for gas that was somewhere between 10 kelvins and 1 million kelvins, a temperature range that would indicate extreme cooling. Using JWST’s Mid-Infrared Instrument (MIRI), they detected warm gas in the core of the cluster, with temperatures around 300,000 kelvins.
The James Webb Space Telescope (JWST) is a space observatory designed to study the universe in infrared light.
Launched on December 25, 2021, JWST is the successor to the Hubble Space Telescope and will focus on observing distant galaxies, stars, and planets.
With its advanced technology, JWST can detect faint signals from distant objects, providing insights into the formation of the first stars and galaxies in the universe.
Its segmented primary mirror is made up of 18 hexagonal segments that unfold once in space.
A Neon Sign in the Dark
The detection of warm gas was like finding a neon sign glowing in the dark. The team analyzed the images and mapped the locations where warm gas was observed within the central galaxy. ‘This 300,000-degree gas is like a neon sign that’s glowing in a specific wavelength of light,’ said study lead author Michael Reefe.
Unraveling the Mystery
The extent of warm gas in the core suggests that the central galaxy is undergoing extreme cooling and generating an enormous amount of stellar fuel. The team estimates that this fuel supply is equal to the mass of about 20,000 suns per year. With this kind of fuel supply, it’s likely that the central galaxy is generating its own starburst, rather than relying on fuel from surrounding galaxies.
Star formation is a complex process that occurs in giant molecular clouds.
These clouds are made up of gas and dust, which collapse under their own gravity.
As the cloud collapses, it begins to spin faster, causing it to flatten into a disk shape.
At the center of this disk, a protostar forms, eventually igniting as a main-sequence star.
This process can take anywhere from 100,000 to 500 million years, depending on various factors such as mass and environment.
New Insights into Galaxy Formation
This study has opened a new way to observe these systems and understand them better. The team says they now have a complete picture of the hot-to-warm-to-cold phase in star formation, which has never been observed before in any galaxy. ‘We think we understand pretty completely what is going on,’ said co-author Michael McDonald. ‘But this new work has opened a new way to observe these systems and understand them better.’
Galaxies are vast, gravitationally bound systems consisting of stars, 'stellar remnants' , interstellar gas, dust, and dark matter.
The formation of galaxies is a complex process that involves the collapse of giant molecular clouds.
These clouds are thought to have formed from the gravitational fragmentation of the universe's earliest gas.
As they collapse, they spin faster and faster, eventually fragmenting into smaller regions that will become individual stars.
This process can take billions of years, resulting in the formation of a galaxy with its characteristic spiral or elliptical shape.
