The inclusion of the ALMA array in a global network of radio telescopes located on different continents, allowed astronomers for the first time to look behind the curtain of a misty cloud of hot gas hiding a supermassive black hole in the center of the Milky Way. The data obtained showed that the jet of a gravitational monster can be directed almost exactly to Earth.
High image quality helped us to limit theoretical models of gas behavior around a source in the heart of our Galaxy, the main part of which radio emission comes from a region with a symmetrical morphology of one three hundred millionth degree. This may indicate that it is produced in a disk surrounding a supermassive black hole, and not in its jet. However, such a phenomenon would make Sagittarius A* exceptional among other black holes glowing in the radio band. An alternative explanation could be a jet pointing to Earth.
-Sarah Issaun, lead author of the study from the University of Nijmegen (Netherlands)
Supermassive black holes are located in the centers of large galaxies and can generate the most energetic phenomena in the known Universe. It is believed that disks of a substance rotate around these invisible objects, some of which are ejected at near-light speed in opposite directions in the form of narrow rays, called jets, producing strong radio emission.
Source Sagittarius A* is the closest to us supermassive black hole, which is about 4 million times heavier than the Sun, and its apparent size in the sky does not exceed one hundred millionth of a degree, which corresponds to the diameter of a tennis ball on the Moon, when viewed from Earth.
To measure its parameters, a technique known as superlong-base radio interferometry (VLBI) is required, which involves locating radio telescopes on different continents in order to “create” a virtual instrument the size of Earth. The resolution achieved by using this method additionally increases the frequency of observations. The highest frequency today for VLBI is 230 GHz.
The first observations of Sagittarius A* at 86 GHz were made 26 years ago. Over the past years, the quality of data and their processing capabilities have constantly improved as more telescopes are attached.
-Anton Census, director of the Institute of Radio Astronomy. Max Planck (Germany)
Combining ALMA with the global network and reaching a resolution twice as high as in previous observations at a frequency of 86 GHz, the team was able to evaluate the properties of light scattering that hides Sagittarius A* from us. This helped them to eliminate most of his effects and get the first image of the neighborhood of a black hole.
Despite the fact that scattering blurs and distorts the image, the incredibly high resolution of the observations made allowed us to determine its exact properties and eliminate its influence. Experience has shown that scattering does not prevent the Event Horizon telescope from seeing the shadow of a black hole at 230 GHz, and this is great news!
-Michael Johnson, co-author of the study from the Harvard-Smithsonian Center for Astrophysics (USA)
The jet of a supermassive black hole Sagittarius A* can point exactly to Earth
Click To Tweet
The post The jet of a supermassive black hole Sagittarius A* can point exactly to Earth appeared first on Upcosmos.com.