Astronomers spotted a new galaxy while investigating a deep space object
Astronomers at the Atacama Large Millimeter/submillimeter Array (ALMA) studying a quadruply lensed quasar called MG 0414+0534 have made an accidental discovery in the quasar’s vicinity. What they’ve found is a dusty, dark dwarf galaxy or an ultra-diffuse galaxy (UDG), which until now had escaped the detection of optical, near-infrared and radio telescopes.
The quasar was being investigated because it exhibited some curious properties which astronomers were hoping to understand. A quasar is a compact region surrounding a supermassive black hole. It consists of mass that is flowing in from a surrounding galaxy, into the black hole’s accretion disk. The process releases massive amounts of electromagnetic energy, producing light that can be up to 100 times as luminous as the galaxy surrounding it. MG 0414+0534 is unique in that its electromagnetic flux has anomalous properties and shows a reddening in the optical and near infrared wavelengths it’s emitting.
Kaiki Taro Inoue of Kindai University in Japan and his team performed continuous observations of the quasar in June and August of 2015, and when they analyzed the data, they discovered a faintly luminous object near the quasar, which they called “Object Y”. According to the paper released by the team, the object’s size is at least 16,300 light years across. They estimate that the dark matter plus baryon mass of the object is about one billion solar masses, while its dust mass is approximately 10 million times greater than that of the sun.
Data from the quasar observations. Object Y is circled.
“Our findings suggest that the object is a dusty dark dwarf galaxy,” reads the paper, but the scientists are also open to the possibility that the object is an ultra-diffuse galaxy (UDG). Such galaxies have a very low density, the largest ones being roughly the size of the milky way, but containing only about one percent of the number of stars. The phenomenon of UDGs still puzzles scientists as they attempt to explain why such galaxies aren’t ripped apart by the gravitational tides of neighboring galaxies.
The team has concluded that a more detailed analysis of the object can shed more light onto its nature and past.