3C 297 is located about 9.2 billion light-years away in the constellation of Virgo and contains a quasar, a supermassive black hole pulling in gas at the center of the galaxy and driving powerful jets of matter seen in radio waves.
This image features 3C 297 that is lonelier than expected after it likely pulled in and absorbed its former companion galaxies. In this new composite image, Chandra data is colored purple, VLA data is red and Gemini data is green. Visible light and infrared data from Hubble (blue and orange respectively) have also been included. Image credit: NASA / CXC / University of Torino / Missaglia et al. / ESA / STScI & International Gemini Observatory / NOIRLab / NSF / AURA / NRAO / AUI / NSF.
The environment of 3C 297, appears to have the key features of a galaxy cluster, enormous structures that usually contain hundreds or even thousands of galaxies. Yet this galaxy stands alone.
This result made with NASA’s Chandra X-ray Observatory and the International Gemini Observatory may push the limits for how quickly astronomers expect galaxies to grow in the early Universe.
“It seems that we have a galaxy cluster that is missing almost all of its galaxies,” said Dr. Valentina Missaglia, an astronomer at the University of Torino.
“We expected to see at least a dozen galaxies about the size of the Milky Way, yet we see only one.”
Dr. Missaglia and her colleagues see two key traits of a galaxy cluster in the Chandra X-ray data.
First, the X-ray data reveals the lone galaxy is surrounded by large quantities of gas with temperatures of tens of millions of degrees — something normally seen in galaxy clusters.
Second, the supermassive black hole’s jet has created an intense source of X-rays about 140,000 light-years away, implying that it has plowed into gas surrounding the galaxy.
A third trait of galaxy clusters possessed by 3C 297, previously reported in Karl G. Jansky Very Large Array data, is that one of the radio jets is bent, showing that it has interacted with its surroundings.
Despite having these important features of a galaxy cluster, the new data from the Gemini Observatory revealed that none of the 19 galaxies that appear close to 3C 297 in an optical image, and that have accurate distance measurements, are actually at the same distance as the lonely galaxy.
“The question is, what happened to all of these galaxies?” said Dr. Juan Madrid, an astronomer at the University of Texas, Rio Grande Valley.
“We think the gravitational pull of the one large galaxy combined with interactions between the galaxies was too strong, and they merged with the large galaxy.”
“For these galaxies apparently resistance was futile.”
The researchers think 3C 297 is no longer a galaxy cluster, but a ‘fossil group.’ This is the end stage of a galaxy pulling in and merging with several other galaxies.
While many other fossil groups have been detected before, this one is particularly distant, at 9.2 billion light-years away.
“It may be challenging to explain how the Universe can create this system only 4.6 billion years after the Big Bang,” said Dr. Mischa Schirmer, an astronomer at the Max Planck Institute for Astronomy.
“This doesn’t break our ideas of cosmology, but it begins to push the limits on how quickly both galaxies and galaxy clusters must have formed.”
A paper on the findings was published in the Astrophysical Journal Supplement Series.
Valentina Missaglia et al. 2023. Powerful Yet Lonely: Is 3C 297 a High-redshift Fossil Group? ApJS 264, 6; doi: 10.3847/1538-4365/ac9f3e
Source : Breaking Science News