Astronomers have observed a gigantic cosmic “trail” in a distant galaxy. The trail of gas and dust may have been caused by the passage of a huge black holealthough there are other possible causes, scientists report in a new study.
The contrail was spotted in the spiral galaxy NGC 3627, located about 31 light-years from our solar system in the constellation Leo.
Zhao and his co-author Guang-Xing Li stumbled upon the galactic trail while analyzing data collected by the High angular resolution physics of nearby galaxies (PHANGS). Using a range of telescopes, including the James Webb Space Telescope (JWST) and the Atacama Large millimeter/submillimeter array (ALMA) in Chile, this study aims to investigate how gas and star formation influence and are influenced by the structure and evolution of galaxies. While the PHANGS-JWST data revealed that NGC 3627’s contrail contains dust particles, the PHANGS-ALMA data suggested that it was also rich in carbon monoxide.
The contrail is a faint linear tail of gas and dust that appears distinct from the two spiral arms of the galaxy. Based on theory model Li co-developed in 2021, Zhao and Li think of a massive and compact object, like a black holewas probably responsible for its creation. The model suggests that when the object passed through the galactic disk, it expelled the gas, leaving behind the trail marking its passage. The enormous turbulence within NGC 3627’s trail supports this model.
The contrail’s characteristics allowed researchers to estimate that the compact object measured about 10 million solar masses and was traveling at a dizzying speed of 186 miles per second (300 kilometers per second), or 50 percent faster than the current speed record for a spacecraft, held by the Parker solar probe. Additional calculations indicate that the contrail formed 20 million years ago, which is relatively recent in astronomical terms. (The Milky Way is over 13 billion years old, for comparison).
Although the researchers suggested that this compact object could be a huge black hole, they noted that it could also be the dense core of a dwarf galaxy.
“Currently, with the available data, we cannot make a definitive distinction between these two possibilities,” Zhao said. “The predicted mass matches both scenarios. Direct detection of the object itself is very difficult: if it is a faint dwarf galaxy, it would be too dark to be seen easily at the distance of NGC 3627. Future extensive optical studies or very high-resolution ALMA observations may one day reveal a counterpart.”
Researchers have also suggested that mysterious red, compact objects known as “small red dots” may also be responsible, although they haven’t yet figured out exactly how.
Zhao and Li plan to continue studying the contrail and will look for more of these flows in PHANGS observations.
“Understanding their evolution and frequency could tell us a lot about the population of massive dark objects flying through galactic disks,” Zhao said.
The study, which has not yet been peer-reviewed, is available as a pre-publication on the arXiv server.
