A new formula for "weighing" black holes

A new formula for weighing black holes

A new empirical formula has been developed to be able to measure the mass of the enormous black holes of active galaxies. The study in Astrophysical Journal

(Photo: Nasa) How can we accurately weigh the huge black holes at the center of active galaxies (Ang), those that emit a huge amount of energy and have a mass of up to to 10 billion times that of the Sun? To try to answer this question today is an international team of researchers, coordinated by Elena Della Bontà, astronomer of the University of Padua and associated with the National Institute of Astrophysics (Inaf), which has just developed a sort of "balance ”, Which is based on an empirical formula thanks to which the mass of a black hole can be measured by analyzing the emission spectrum, that is the radiation emitted by the gas that comes from the surrounding regions. The study was published in the Astrophysical Journal.

In order to develop an instrument that would allow black holes to be weighed, the researchers created a new formula, which is based on “a single measurement of width and brightness of the emission lines produced by the gas heated and ionized by ultraviolet radiation near the black hole, ”explain the researchers. According to observations, a black hole at the center of an active galaxy has a mass equal to 0.2% of the total mass of the stars of the galaxy in which it resides.

A fact that, together with others that suggest associations between the mass of black holes and the properties of galaxies, highlights how the mechanisms that regulate the increase in size of black holes are linked to the processes that drive the evolution of galaxies. So far, however, studies of how these relationships vary over cosmological times have been quite limited.

Thanks to the development of this new formula, researchers will now be able to use it to determine the mass of black holes in different red-shifts (literally "red shift") and study the parallel evolution of black holes and galaxies as a function of cosmic time. "We started by collecting and selecting the best photometric and spectroscopic data for all Agn monitored to date, both by our group and by other astronomers, in order to study the dimensions and kinematics of the region in which the gas is swirling around. to the central black hole ", explains the author of the study in a note:" And we have finally calibrated a relationship that allows us to obtain in a simple and accurate way the mass of the black hole from a single spectroscopic observation, and which can be applied to all campaigns for spectroscopic observations of active galaxies ".

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