Australopithecus would have seen the gigantic eruption of the black hole in the center of the Milky Way

About 3.5 million years ago, the supermassive black hole of the Milky Way would have suddenly returned to activity by accreting a cloud of gas containing the equivalent of 100,000 solar masses. The resulting cosmic eruption would have illuminated galactic matter for almost a million years, matter clearly visible to hominins of the time.

About 3.5 million years ago, hominins moved around in Africa, some were Australopithecus afarensis like the famous Lucy. If we only consider this species was behind the genre Homo, it may be the case with gender Australopithecus. We know at least that, at that time, there were hominins capable of standing at least temporarily upright as evidenced by the discovery of the famous track formed offootprints which was uncovered in Laetoli, Tanzania.

What is also certain, and retrospectively more astonishing, is that some of these hominins are going to have for descendants today a group of humans from the noosphere of Teilhard de Chardin led by Andrew Fox of Space Telescope Science Institute (STScI) in Baltimore. Become astronomers, they probably brought millions of years later an answer to questions that their ancestors may have already asked themselves by raising their heads towards the sky at night, contemplating a particularly bright region of the Milky Way in the constellation of Sagittarius. It is in any case to this hypothesis that we are led if we believe an article published in the famous Astrophysical Journal and which can be found in free access on arXiv.

Colossal plasma bubbles produced by Sgr A *

This scenario was already advanced last year but is therefore now officially released. It is also based on a discovery that was made a decade ago with the Fermi satellite which observes in the field of gamma rays. The observations of this eye sure orbit of humanity today supplements that of another capable of examining the mysteries of the cosmos in the field of rays ultraviolet and we just celebrated 30 years in space: the Hubble Space Telescope.

10 years ago, as a previous ABSMARTHEALTH article explained below, the astrophysicists have highlighted existence above and below the nucleus of the Milky Way bubbles plasma called from Fermi bubbles. They range to around 30,000 light years on both sides of the galactic plane and, according to astrophysicists, they result from a gigantic eruption which occurred approximately 3.5 million years ago at the level of the accretion disc surrounding the supermassive black hole of 4 million masses in the heart of the Milky Way in the constellation Sagittarius.

Sgr A *, as it is called, would therefore have seen its activity suddenly increase due to the arrival in its surroundings of a huge cloud of gas probably containing the equivalent of about 100,000 solar masses. The deluge ofenergy caused by the accretion of this gas and instabilities in the accompanying process would therefore have led not only to the formation and ejection of this plasma but also to a generous radiation in the field of ultraviolet.

Fermi's bubbles. To obtain a fairly faithful translation into French, click on the white rectangle at the bottom right. 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". © Nasa's Goddard Space Flight Center

Ionized hydrogen clouds illuminated by UV waves

Hubble and sound spectrograph COS (Cosmic Origins Spectrograph) helped trace this cataclysm by highlighting the presence of certain lines ofabsorption in a band of wave length of ultraviolet. These lines are observed in the light coming from 21 and 10 quasars having crossed in the first case the famous magellanic current and, in the second case, the Leading Arm, huge gaseous structures torn from the Great and Small Magellanic Cloud, dwarf galaxies well known irregulars in the vicinity of the Milky Way.

The Leading Arm is about half the size of the Milky Way and is estimated to be 1 or 2 billion years old. The matter which composes it seems to come from the Small Magellanic Cloud which would have undergone the tidal forces of Large Magellanic Cloud. The Magellanic current would also come mainly from the Small Magellanic Cloud but also partly from the Large Magellanic Cloud, as Andrew Fox and his colleagues had already shown. the light of quasars few years ago.

The absorption lines discovered by Hubble can be easily explained if we admit that about 3.5 million years ago the matter of the Magellanic current – but not that of the Leading Arm which is not really above the galactic bulb of the Milky Way – has been partially ionized by the flow of ultraviolet radiation emitted by the accreted matter on Sgr A *. Matter of the mass equivalent of 100 million suns would have illuminated in response to this flood of UV and calculations indicate that it would have remained particularly bright for perhaps up to a million years. Looking towards the center of the Milky Way, the first hominins would therefore have contemplated during this period a spectacle which is no longer accessible to us today.

Milky Way: our supermassive black hole smokes under the eyes of Fermi and XMM-Newton

Article by Laurent Sacco published on 03/25/2019

Astrophysicists have been busy mapping gamma and gamma maps for years X-rays, especially in its central regions. They discovered bubbles and columns of plasma hotter there than the Sun which undoubtedly testify to an abrupt activity of its supermassive black hole only a few million years ago.

We know that supermassive black holes grow hand in hand with large spiral galaxies that house them. We are not sure why or how, although we have good reason to believe that part of this phenomenon stems from the fusion repeatedly galaxies since their birth, in the form of dwarf galaxies more than 13 billion years ago in the observable cosmos.

We also have good reason to think that gas and news content stars of galaxies is influenced by the fluxes of matter and radiation that these black holes can emit when they accrete matter, and in particular when they behave like quasars.

To try to see more clearly, the astrophysicists therefore undertook to study the nearest supermassive black hole at our disposal, which therefore allows to have the most precise and complete details possible. This is obviously the one containing about 4 million solar masses and which is in the center of the Milky Way. It was originally discovered as a powerful source radio whose name is Sagittarius A *, located in the direction of the zodiac constellation Sagittarius.

This name and its diminutive Sgr A * now designate thestar compact lurking at the heart of our Galaxy which is the subject of multiple studies. Studies to also verify that we are indeed in the presence of a black hole, and not of a wormhole for example, or at Review alternatives to Einstein's theory of gravitation, the general relativity, when it is not also a question of demonstrating the existence of the black matter.

Astrophysicists and specialists in astroparticles study the immediate surroundings of Sgr A * in the field of gamma rays and X-rays. As ABSMARTHEALTH explained in 2010 in the article below, giant bubbles of matter were discovered in 2010 by the space ray telescope Fermi gamma of the Nasa, one extending above the plane of the Milky Way and the other below, forming a colossal hourglass covering about 50,000 light years, or about half the diameter of the entire Galaxy. These hot bubbles must contain very energetic charged particles which it is likely to think that they come from a period when Sgr A * was much more active in the not very distant past and when it increased much more gas.

In 1895, the German physicist Wilhelm Röntgen discovered radiation of which he did not know the nature, he baptized them therefore X-rays. One of the most known applications of these rays is done in medical imagery. In space, we are mainly interested in the sources that emit these rays. The ten years of the XMM-Newton mission are the theme of this edition of "Space". © euronews (in French)

Sagittarius A * smoking under the eyes of XMM-Newton?

Studies on these bubbles continued, in particular by an international team involving astrophysicists from the Department ofastrophysics CEA-Irfu, CNRS, Astroparticule laboratory and cosmology of Paris (APC, CNRS / Université Paris Diderot / CEA / Observatoire de Paris) and of the Institute of Planetology and Astrophysics of Grenoble (Ipag, CNRS / Université Grenoble Alpes) with the support of the National Center for Space Studies ( Cnes).

They were carried out this time in the X-ray field with around fifty observations totaling more than 300 hours between 2016 and 2018 using the European satellite XMM-Newton.

It was in fact precisely a question of establishing a large-scale map of theprogram in X-ray of the region of the center of the Milky Way. This map then revealed the existence of two columns of hot plasma (at temperatures of several million degrees) in the Fermi bubbles and located on either side of the galactic plane about 500 light years apart at each times, as explained in the article published in Nature by astrophysicists.

These columns rise directly above Sgr A * and it is tempting to see there too the traces of a revival of activity of our central black hole in the fairly close past (a few million years at the most more, whereas today it is only associated with strong radio radiation, very low emission of X-rays as well as a few bursts weak brightness in infrared.

This possibility is also mentioned in a press release by Andrea Goldwurm, CEA researcher and from the Astroparticle and Cosmology laboratory in Paris, co-author of this discovery, which explains that: "The most convincing assumption is that the fireplaces of hot gas that we discovered could be the channel that transports energy from the active region of the center of the Galaxy to the outside, thus feeding the Fermi bubbles, as their morphology. "

But caution is required, as Maïca Clavel, CNRS researcher at the Institute of Planetology and Astrophysics in Grenoble, and also co-author of the publication in Nature which adds in the CEA press release that: "Although this link seems to suggest, due to the likely intermittence of the energy injection from the central regions, the black hole radio broadcast map does not directly support the idea that chimneys are a continuation of the internal radio lobes. "

The center of the Milky Way is indeed very rich in stars. It cannot therefore be excluded that we are in the presence of concentrations of supernova or simply the effect of winds matter of very hot and very massive young stars.

The investigation therefore continues.

Fermi discovers two gigantic lobes emitted by the Milky Way

Article by Laurent Sacco published on 10/11/2010

The Fermi satellite has just made an astonishing discovery. Two lobes emitting gamma rays rise on either side of the galactic bulb. Spanning a total length of 50,000 light years, this structure could be related to past activity of the central black hole.

Carl Sagan would be with us today, the discovery announced on November 9, 2010 would have been a great birthday present for him, even if it does not concern theexobiology. A team of astrophysicists using the telescope instruments Fermi to gamma map the celestial vault has indeed discovered a vast structure spanning nearly 50,000 light years between the constellation Virgo and that of the Crane.

It is in the form of two lobes located on either side of the Milky Way disc and seeming to rise like gas plumes from the central galactic bulb. It comes from a diffuse gamma ray emission caused by theCompton effect reverse. So it's aboutelectrons very energetic colliding with photons low energies and giving them part of it. The net result is the production of gamma photons diffuse more energetic. The origin of these electrons is however not clear.

The structure discovered by the researchers is not directly visible on a raw image of the celestial vault provided by Fermi, such as that resulting from 2 years of observations. We had to process the images to make it fully visible.

The hypotheses on the presence of these two lobes

At the moment, astrophysicists are not sure how to interpret its existence. It could be the residue of a past activity of the central black hole of the galaxy. We observe similar lobe structures for several active galaxy nuclei. It is moreover very likely that the supermassive black hole at the heart of the Milky Way was itself a quasar billions of years ago.

It could also be a plume of matter caused by a sudden formation of stellar clusters opened in the galactic bulb, only a few million years ago. Here too, abrupt and significant releases of gas streams during such a process are observed in other galaxies.

Fermi's bubbles. To obtain a fairly faithful translation into French, click on the white rectangle at the bottom right. 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". © Nasa's Goddard Space Flight Center

The structure itself has been partly visible for several years in observations made in the X-ray field, this time by the Rosat satellite. The data provided by WMap also showed a curious excess in the microwave domain, in the region now revealed in gamma by the instrument. LAT from Fermi.

Mysterious, this structure could give important information about our galaxy.

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