National Astronomical Observatory of Japan

Unique Chemical Composition Surrounding Supermassive Black Hole – A Step toward Development of New Black Hole Exploration Method

| Science

The Atacama Large Millimeter/submillimeter Array (ALMA) successfully captured a detailed image of high density molecular gas around an active galactic nucleus harboring a supermassive black hole. The observations at the highest ever achieved reveal a unique chemical composition characterized by enhancement of hydrogen cyanide (HCN) around the black hole. An research team thought a high temperature affected by the black hole caused this peculiar chemical properties. The team expect that this unique chemical properties can be used to find black holes hidden behind dust.

Figure 1
Spiral galaxy NGC 1097 observed with European Southern Observatory’s Very large Telescope in optical wavelength (left) and the central 2100 light years observed with ALMA (right). The ALMA observations reveal intense emission from dust around the central black hole and in the circum-nuclear star burst ring. The star sign shows the location of the emission peak in near infrared, which reflects the star formation activity, whereas the central plus sign shows the location of the radio emission peak in the wavelength of 6 cm which comes from the active supermassive black hole. The emission peak position in the ALMA image agrees well with that of 6 cm emission. This ensures that ALMA detects the emission from the vicinity of the central black hole.

The research findings are presented in the article “Submillimeter ALMA Observation of the Dense Gas in the Low-Luminosity Type-1 Active Nucleus of NGC 1097” published in the Publication of the Astronomical Society of Japan, Vol. 65, of October 25, 2013.