Giant black holes are not all wisely lurking in the heart of galaxies. Some are nomadic and can sometimes be observed in the X-ray field, probably following an encounter with a star. Recent simulations of collisions between galaxies containing these giant black holes now suggest that about 10% of the mass of the cosmos contained in supermassive black holes is in gender stars wandering in the dark matter halos of galaxies.
In the early 1960s, the discovery ofstunned them . If one took their spectral redshifts seriously in accordance with the Hubble-Lemaître law, they had to be considered as several billion apart. and incredibly bright, too much for the radiation produced to be the effect of thermonuclear reactions in stars. Also, from 1964, the big Russian Yakov Zel’dovich and Igor Novikov (and the US ) had they proposed that the , more generally , be accreting matter. In 1971, Donald Lynden-Bell and Martin Rees proposed for their part that there was one in the heart of the . At least since the early 1990s, it seemed clear that most large were probably to shelter in their center one of these compact stars, which the observations did not cease supporting. Today, we can even make images of it, as the members of .
Observations also show colliding galaxies and it has become clear that in at least some cases thegalaxies would lead to fusions of supermassive black holes, which contributed to their growth and partly accounted for the masses reached by these objects, ranging from a few million to several tens of billions of solar masses. In fact also, we clearly see in some galaxies two or even three supermassive black holes, which is easily explained if this growth mechanism is operative. We have had reason to think despite everything for ten years, first because of simulations and finally there also of observations, .
A video about Romulus and the wandering supermassive black holes. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © YaleCampus
Supermassive black holes that do not “settle” in the heart of galaxies
Among the scholarly cosmological simulations onallowing us to understand what is happening in the kingdom of galaxies and their interactions with the supermassive black holes they contain, there is one called . It takes into account a large number of celestial bodies and a series of loops of deriving from several phenomena falling within a description in play. The Romulus simulation takes into account in particular a more precise matter by a supermassive black hole as well as the famous formula known as ” »By the great Indian astrophysicist and Nobel Prize winner Chandrasekhar describing the loss of of a massive celestial body, like a or a black hole, in in the self-gravitating stars in a galaxy.
In the context of the Romulus simulation, taking this formula into account shows in particular that supermassive black holes can take a long time to enter.after the merger of the two galaxies that contained them, or even stay in around the galaxy produced.
Astrophysicist Angelo Ricarte, from Center for Astrophysics | Harvard & Smithsonian (CfA) has just published with his colleagues Michael Tremmel, Priyamvada Natarajan, Charlotte Zimmer, all of Yale University, and Thomas Quinn of the University of Washington, an interesting article in Monthly Notices of the Royal Astronomical Society and free access on , reporting new results on this subject with the Romulus simulation.
This is the continuation of work that they have been carrying out on this subject for several years and they announce that they have arrived at an astonishing prediction. About 10% of thecontained in the form of supermassive black holes is not found in the form of these compact stars in the heart of galaxies but in the form of supermassive black holes wandering around large galaxies, in their halo of , and left in this situation during minor galaxy mergers.
This portion was larger and larger as we go back in the past.
Chandra discovers wandering black hole of 100,000 solar masses
Article bypublished on 10/10/2016
Giant black holes are not all wisely lurking in the heart of galaxies. Some are nomads. We have just discovered the brightest of them in the field of, probably following his encounter with a star he devoured billions of years ago.
Thefollowed by mergers are frequent in the cosmos. It is also believed that part of the growth process of galaxies is done in this way, the other part involving currents of cold gas that these objects accrete.
As massive black holes are present in almost all galaxies – in the form of black holes offor the smallest and in the form of supermassive black holes for the largest – black hole mergers must also occur.
We sometimes observe, in a galaxy, the presence ofin his heart, testifying to a recent merger on the scale of the history of . These black holes are detected in particular by X-rays from a of hot matter that forms when they accrete matter.
Black holes are among the most opaque objects in the universe. Fortunately, on the other hand, they are among the most attractive, and it is by their disproportionate power of attraction that we can detect them. Giant black holes are the most monstrous ogres in the Cosmic Zoo, but they are not weapons of mass destruction. The jets of matter they eject would have helped light the first stars and form the first galaxies. © ECP Group,, via YouTube
A very bright X-ray source
Astrophysicists who study these phenomena therefore rely particularly onX-ray systems put into orbit (the most famous are , for the , and XMM , for’ ). An article available on also announces that a fascinating discovery was made by patiently analyzing the data collected by these instruments by observing a region of the sky of which about 500 images taken by the Hubble Space Telescope were gathered to constitute the extended Groth band, in English Extended Groth Strip1 (EGS1). It is a wide-field image of a region between the and that of Bouvier.
In the early 2000s, Chandra and XMM Newton detected there a particularly bright but transient source of X-radiation which now appears in the archives of astrophysicists under the name XJ1417 + 52. Measurements indicate that it was 4.5 billion light years from the, right next to a called SDSS J141711.07 + 522540.8, or more soberly GJ1417 + 52.
A black hole, a remnant of a dismantled dwarf galaxy?
XJ1417 + 52 was clearly one of the hyper bright X sources or in English hyper-luminous X-ray source (HLX). The amount of energy released in this area ofand its characteristics are easily explained if we are in the presence of a black hole accreting matter and whose mass must be around 100,000 solar masses, therefore a black hole of intermediate mass, since supermassive black holes contain from a few million to a few billion solar masses.
The source XJ1417 + 52 not being located in GJ1417 + 52, it is about a wandering black hole, also called nomad. This probably belonged to apassed too close to the and which was dismantled by the .
We already knew of such nomadic black holes but, at the maximum of X emissions, thereached by XJ1417 + 52 exceeded by a factor of 10 that of other stray black holes detected so far. Moreover, this source holds another record: it is 10 times farther away than that associated with the previous nomadic black hole which held the distance record.
It is reasonable to assume that the X-luminosity peak occurred when a star got too close to the intermediate black hole and underwent similar processing to the scenario of the, proposed a few decades ago by and Brandon Carter.