The galaxy Markarian 509 (Mrk 509) is a very complex system, long under the gaze of astronomers to understand how the development of stars and the growth of the black hole in a galaxy co-evolve. In a recent Italian study by various institutions (SISSA, University of Trieste, INAF, Institute for fundamental physics of the Universe) the molecular gas tank, the ideal habitat for the birth of stars, available to Mrk 509. Furthermore, two discoveries perturbations inside the tank, galactic winds. All important information to understand the kinematics of clouds of molecular gas and their role in the activation process of black holes and galaxies.
A medium-sized system at 466 million light years, the Mrk 509 galaxy is characterized by strong activity: it presents a ionized gas disk it’s a starburst ring, region generally with a high rate of star formation, process in Mrk 509 currently underway and estimated at a rate of about five solar masses per year. The galaxy is also experiencing one minor fusion, a phenomenon of absorption of most of the gas and stars of a smaller nearby galaxy. According to the authors, these two factors, the star-forming molecular disk and the minor fusion, involve the destabilization of the galactic molecular gas, phenomenon that fuels both star formation and the activation of the black hole and the galaxy.
When galactic gases are carried by the perturbations, they approach the black hole at the galactic center. The hole thus evolves into a active galactic nucleus, entities characterized by the presence of highly ionized gas not correlated with stellar activity. Following this event, a large amount of radiation and matter is released that can influence the gas of the galaxy itself, which thus becomes itself active, giving rise to a complex stimulus and feedback cycle among the stellar production of the galaxy and, in the galactic center, the increase of active galactic nucleus. The phenomenon of mutual activation and power is extinguished when the propellant runs out, ie when most of the cold gas is expelled from the system.
Studying galactic winds and molecular clouds within an active galaxy such as Mrk 509 can provide a greater understanding of the evolution of the entire galactic system. However, during the first phases of activation of the black hole in the active nucleus, it is thought that most of the primary radiation due to star formation and activity in the nucleus is strongly obscured and almost invisible at wavelengths such as optical or ultraviolet ones. .
For this reason, in order to find further evidence of the presence of molecular gas winds in Mrk 509, the team of Italian astronomers analyzed Mrk 509 according to the data from the observations of ALMA (Atacama Large Millimeter / submillimeter Array) one of the most powerful telescopes in the world, located in the Atacama desert in Chile at an altitude of 5000 meters. ALMA represents a particularly effective solution for observing molecular cold gas in active galaxies, being the telescope a system of 66 antennas that exploits the interferometric technique, thus operating a wavelengths between 0.32 and 3.6 mm. The Mrk509 galaxy was selected from the IbisCO sample, consisting of 60 nearby galaxies observed with ALMA.
The Italian team, led by Maria Vittoria Zanchettin of the University of Trieste, has thus identified in Mrk 509 a tank of molecular gas equal to 1.7 billion solar masses, located within the galactic disk approximately 17,000 light years in size. The disk, inclined by 44 degrees and with a mass of about 20 billion solar masses, contains within it a fraction of molecular gas estimated by the team of about 5% of the disk itself.
Research has also found significant perturbations of molecular gas kinematics in two different points of the disk, deviations caused by the rotation of the disk and which have been interpreted as molecular winds, therefore called wind A and wind B. The Italian astronomers have calculated that the wind A has a speed of approx 250 km/s and is located at a distance of about 980 light years from the active galactic nucleus. The wind B, from 200 km/s, was identified at a distance of approximately 4,600 light years from the active center.
A breath of fresh air on the study of galactic gases for a greater understanding of their role in the processes of galactic evolution.
Credits. Featured image: NASA, ESA, J. Kriss (STScI) and J. de Plaa (SRON)