Webb Telescope Uncovers Abundant Hydrocarbons in Distant Galaxy's Core
Astronomers using the James Webb Space Telescope have detected an unexpected abundance of small gas-phase hydrocarbons in the obscured nucleus of the ultra-luminous infrared galaxy IRAS 07251-0248, located in the constellation Monoceros.
Astronomers utilizing the James Webb Space Telescope (JWST) have identified a significant presence of small gas-phase hydrocarbons, including benzene, methane, acetylene, diacetylene, triacetylene, and the methyl radical, in the heavily obscured nucleus of the ultra-luminous infrared galaxy IRAS 07251-0248, situated in the constellation Monoceros. This marks the first extragalactic detection of the methyl radical.
The galaxy's core is enshrouded by substantial amounts of gas and dust, which absorb most radiation from its central supermassive black hole, rendering it challenging to study with traditional telescopes. However, JWST's infrared capabilities have enabled researchers to penetrate this dust, revealing the dominant chemical processes within these regions.
Dr. Ismael García Bernete and his team employed spectroscopic observations from JWST's NIRSpec and MIRI instruments, covering wavelengths from 3 to 28 microns. These observations allowed for the detection of chemical signatures from gas-phase molecules, as well as features from ices and dust grains. The data revealed an unexpectedly rich inventory of small organic molecules, including benzene, methane, acetylene, diacetylene, triacetylene, and the methyl radical.
In addition to gas-phase molecules, a large abundance of solid molecular materials was found, such as carbonaceous grains and water ices. Dr. García Bernete noted that the findings indicate a continuous source of carbon in these galactic nuclei, fueling a rich chemical network. Professor Dimitra Rigopoulou from the University of Oxford highlighted that these molecules could play a key role as fundamental building blocks for complex organic chemistry, relevant to processes associated with life.
The study suggests that the erosion and fragmentation of carbonaceous grains and polycyclic aromatic hydrocarbons, possibly driven by cosmic rays, contribute to this rich hydrocarbon chemistry. These hydrocarbons are outflowing at approximately 160 km/s, which may represent a potential formation pathway for hydrogenated amorphous grains.
The research was published in the journal Nature Astronomy.