ALMA telescope just captured an image of the rotating dusty gas torus. It swirls around the supermassive black hole of M77.
So, astronomers have talked about the existence of such rotating structures decades ago. But this is the first time they’ve confirmed one so clearly.
The supermassive black hole lies in the galaxy M77, a relatively nearby barred spiral. It is located some 47 million light-years away in the direction of the southern constellation Cetus the Whale.
So, using ALMA, the team imaged the area around M77’s center. Hence, they were able to resolve a compact gaseous structure with a radius of 20 light-years.
The motion of gas around the supermassive black hole in the center of M77. The blue color indicates the gas moving toward us. The red shows gas moving away from us. Credit: ALMA (ESO/NAOJ/NRAO), Imanishi et al.
Like most massive galaxies, M77 has an Active Galactic Nucleus (AGN), where the SMBH (Supermassive Black Hole) is sucking the dust and gas rotating around it. Thus, leading to higher than normal luminosity.
“To interpret various observational features of AGNs, astronomers have assumed rotating donut-like structures of dusty gas around active supermassive black holes. Astronomers call this the ‘unified model’ of AGN. However, the dusty gaseous donut is very tiny in appearance. With the high resolution of ALMA, now we can directly see the structure,” Masatoshi Imanishi explained in an ALMA press release.
“Previous observations have revealed the east-west elongation of the dusty gaseous torus. The dynamics revealed from our ALMA data agrees exactly with the expected rotational orientation of the torus,” said Imanishi.
However, the study of SMBHs is very challenging. The closest SMBH (Sagitarrius A*) is relatively quiet, with only a small amount of gas accreting onto it. At the same time, it lies at the center of our galaxy, where intervening dust, gas and stars obscure it. So, this forces astronomers to look to other galaxies to study how SMBHs and their galaxies co-exist.
Thumbnail image: Artist’s impression of the dusty gaseous torus around an active supermassive black hole. ALMA revealed the rotation of the torus very clearly for the first time. Credit: ALMA (ESO/NAOJ/NRAO)