Free Astronomy Magazine November-December 2014

GALAXIES reasons, would on average be more massive than those of other galaxies. In short, everything would seem to indicate the presence of a su- permassive black hole at the cen- tre of M60-UCD1. In order to def- initively confirm its presence, some of the researchers who dis- covered the X-ray emission from the dwarf galaxy (including Anil Seth, University of Utah) have re- cently made a series of spectro- scopic observations of the object (at infrared wavelengths between 2 µ m and 2.4 µ m), using the Near-Infrared Integral Field Spec- trometer of the Gemini North Telescope (Mauna Kea, Hawaii). The aim of the observations was to measure the speed and direc- tion of the motion of the carbon monoxide (CO) in various parts of the small stellar system. By interpreting the kinematic data obtained through a special dynamic model capable of separating the gravita- tional influence of the black hole from the contribution of stars, the researchers (also A nil Seth (above), the astronomer of the University of Utah who led a team of resear- chers to the dis- covery of the su- permassive black hole hiding in- side M60-UCD1. Left, the central region of the For- nax cluster gal- axies, where more than ten years ago were discovered some of the first ultra- compact galaxies, highlighted in the left panels. [M. Hilker et al.] thanks to previous observations made with the Hubble Space Telescope) were able to derive the value of the mass needed to ac- count for the movements detected. Excluding the visible matter, mainly repre- sented by stars, it was found that in the cen- tre of M60-UCD1 there are 21 million solar mas- ses that do not emit light. That is the size of a re- markable supermassive black hole, even without considering that it is lo- cated in a dwarf galaxy. Those 21 million solar masses are the equiva- lent of more than 5 times the size of the black hole hosted by the Milky Way, highlighting a startling disproportion compared to the typical ratio between the gal- axies’ masses and those of their supermassive blacks holes. In fact, the black hole of our Milky Way represents about 0.01% of the total mass, while in the case of M60- NGC 1399 NGC 1404