X-ray image of universe reveals almost 1 million high-energy objects: 'These are mind-blowing numbers'

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By Robert Lea
published

"The scientific breadth and impact of the survey is quite overwhelming; it’s hard to put into a few words."

The first data released to the public from the eROSITA sky survey comprises an X-ray view of half the sky over Earth, encompassing almost a million high-energy cosmic sources, including over 700,000 supermassive black holes.

This catalog, dubbed the "eROSITA All-Sky Survey Catalogue (eRASS1)" was published on Thursday (Feb. 1). It constitutes the largest-ever catalog of the universe's most powerful sources of energy, like exploding massive stars and black hole-powered active galactic nuclei that shine brightly in X-rays. The release also details the largest known structures in the universe — cosmic web filaments of hot gas that connect galaxies in clusters.  

The results show that, in just half a year of operations beginning after launch on July 13, 2019, eROSITA has managed to discover more high-energy X-ray sources than has been found in six decades of examining the sky. 

Considered a major milestone in the 60 or so years of X-ray astronomy, eRASS1 could help answer some of cosmology's biggest questions: How did the universe evolve, and why is the very fabric of space expanding at an accelerating rate? 

Related: Mysterious dark energy is spread evenly across the cosmos

Two versions of eROSITA All-Sky Survey Catalogue (eRASS1) data (Right) the X-ray sky over earth (right) X-ray sources. (Image credit: MPE, J. Sanders für das eROSITA-Konsortium)

Accompanying the eRASS1 data are almost 50 scientific papers published across a range of topics, adding to an existing 200 papers already written using data from the eROSITA telescope.

The main aim of eROSITA is to use clusters of galaxies to observe how dark energy accelerates the expansion of the universe; these 250 or so papers, however, demonstrate the extent to which the instrument and its data have gone beyond this goal. 

These papers include the discovery of over 1,000 superclusters of galaxies, the revelation of two quasi-periodic erupting black holes, and the determination of the impact that stars' X-ray radiation has on water and atmosphere retention of planets that orbit them.

"The scientific breadth and impact of the survey is quite overwhelming; it's hard to put into a few words," spokesperson for the German eROSITA consortium, Mara Salvato, said in a statement. "But the papers published by the team will speak for themselves."

eROSITA lets the numbers do the talking

The eRASS1 data consists of eROSITA telescope observations conducted from Dec. 12, 2019, to June 11, 2020. from across half the sky over Earth. During this period, the space telescope detected around 170 million individual particles of X-ray light or "photons."

Processing these photons revealed 900,000 X-ray sources, of which 700,000 are feeding supermassive black holes that power quasars at the hearts of active galactic nuclei, regions in the centers of galaxies so bright they can outshine the combined light of every star in those galaxies themselves.

Also seen in the eRASS1 are 180,000 X-ray-emitting stars in the Milky Way, 12,000 clusters of galaxies and even exotic classes of X-ray sources like binary stars, supernova remnants, pulsars and other such objects.

"These are mind-blowing numbers for X-ray astronomy," Andrea Merloni, eROSITA principal investigator and first author of the eROSITA catalog paper, said in a statement. "We've detected more sources in 6 months than the big flagship missions XMM-Newton and Chandra have done in nearly 25 years of operation."

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The data release is also impressive in terms of the spread of its observations, with the sky over Earth imaged at multiple X-ray energies. In addition to this, eROSITA is incredibly precise, with its first data release also pinpointing positions in the sky from which individual photons are received, as well as these photons' arrival times and energies. 

Along with the release, the eROSITA Consortium has also made available the software needed to analyze data from the X-ray telescope as well as catalogs that go beyond just X-ray data.

"We've made a huge effort to release high-quality data and software," eROSITA Operations team leader, Iriam Ramos-Ceja, said. "We hope this will broaden the base of scientists worldwide working with high-energy data and help push the frontiers of X-ray astronomy."

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Robert Lea
Robert Lea
Senior Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

8 Comments Comment from the forums
  • Torbjorn Larsson
    Admin said:
    The first eROSITA sky-survey data release involves an X-ray image of half the universe, showing exploding stars and over 700,000 supermassive black holes. It's the largest catalog of high-energy cosmic sources ever.

    X-ray image of universe reveals almost 1 million high-energy objects: 'These are mind-blowing numbers : Read more
    Keen eROSITA-watchers may know that the driving scientific objective that motivated the telescope was to constrain cosmological models using clusters of galaxies. The cosmology results, based on an in-depth analysis of the eRASS1 clusters, will be released in approximately two weeks. Watch this space!
    https://www.mpg.de/21468451/0126-ext0-the-x-ray-sky-opens-to-the-world-151510-x
    Two more weeks!
    Reply
  • Classical Motion
    That's a lot of mass being converted into EM energy. A huge mass loss. And along with it is the amount of gravity it causes.
    Reply
  • billslugg
    There is no loss of mass when matter is converted into energy. Both matter and its energy equivalent have the same mass and the same gravity.
    Reply
  • Classical Motion
    Really? That's against all that science teaches us. So the equivalence is not only a ratio of mass and energy, but a ratio of gravity too?

    Let's convert all mass into light......would they be any gravity?
    Reply
  • billslugg
    Science teaches us that a photon has zero rest mass, however, no photon can be at rest. Light can be "brought to a stop" but that is only because the photon is temporarily tied up in some other form. All photons have energy and all energy has mass.

    There are two forms of mass, they are "matter" and "energy" and are interchangeable with mass always being conserved. Gravity does not change when matter changes into energy. This is because the mass does not change.

    So, yes, a light beam's gravity will affect another light beam.

    i
    Reply
  • Classical Motion
    A photon is never at rest. Before it is emitted it is part of the mass. Because it is confined with momentum. That angular momentum is mass. When we take a portion of it to emit, the angular momentum portion is transferred to a linear momentum as propagation and is cast off.. That is a loss of mass from the emitter.

    When mass absorbs, it gains mass, it gains inertia. Not all light interaction is absorption. Most of it is not absorption. Then the mass is just heated or jiggled. Vibrated.

    When a particle absorbs, is gains mass. When it emits, it losses mass. This is where the equivalence comes from.

    Gravity only comes from mass. EM radiation has no mass and no gravity. There is NO gravitational interaction of light beams.
    Reply
  • billslugg
    Mass is always conserved, there are no exceptions. A mass can take the form of matter or it can take the form of energy. In each case, they have exactly the same mass. Light beams interact through gravity, unless they are traveling parallel to each other, in which case each one sees the other one at rest, thus sees it as massless. Here is a detailed answer I found on Quora:
    Do two beams of light attract each other in general theory of relativity?"The general answer is "it depends." Light has energy, momentum, and puts a pressure in the direction of motion, and these are all equal in magnitude (in units of c = 1). All of these things contribute to the stress-energy tensor, so by the Einstein field equation, it is unambiguous to say that light produces gravitational effects.

    However, the relationship between energy, momentum, and pressure in the direction of propagation leads to some effects which might not otherwise be expected. The most famous is that the deflection of light by matter happens at exactly twice the amount predicted by a massive particle, at least in the sense that in linearized GTR, ignoring the pressure term halves the effect (one can also compare it a naive model of a massive particle at the speed of light in Newtonian gravity, and again the GTR result is exactly twice that).

    Similarly, antiparallel (opposite direction) light beams attract each other by four times the naive (pressureless or Newtonian) expectation, while parallel (same direction) light beams do not attract each other at all. A good paper to start with is: Tolman R.C., Ehrenfest P., and Podolsky B., Phys. Rev. 37 (1931) 602. Something one might worry about is whether the result is true to higher orders as well, but the light beams would have to be extremely intense for them to matter. The first order (linearized) effect between light beams is already extremely small."
    Reply
  • Classical Motion
    Simplicity is the most confounding thing. It would be impossible for physicality to be more simple than it is. And no one sees this.

    Motion can be conserved and ratio-ed between energy and mass without loss. But almost all emission has loss. Most is constantly dissolving into space. Where it can never interact again. This universe has lost energy and mass since the very beginning. And will continue to do so.

    Energy is just the property of a thing. There are only two things. Charge with a field around it, and the emitted field from it. That's it. That's all the physical entities in the universe. Also the structure of the charge is the only physical structure in this universe. All other structures are combinations of that one structure.

    This makes understanding things very easy.

    What is a property of a thing. A property is an innate characteristic of a thing. Innate means the characteristic is always with the thing.

    Energy is the property of motion of a thing. If the thing moves, the thing has energy. There are two forms of motion. One form is confined motion. The other is unconfined motion. Confined motion has the property of inertia. We call it mass. The motion of charge is confined. This confined field motion can be emitted. Once emitted, the field has unconfined motion. It goes everywhere. It radiates. The charge looses inertia. E=Mc2 is just a ratio of motion forms. Unconfined/confined. This exchange between them is done with squared spin. Because motion is confined with a squared spin.

    A charge can confine, unconfined motion and a charge can unconfine, confined motion. Convert angular EM to linear EM and visa versa. They can pitch or catch. They are a EM field converter electrical devices. That's the function of charge.

    Whatever gravity is, it's a collective force. It only occurs when charge combines. And only other combined charges, respond to it. It's a dipole interaction.

    I think the asymmetric inertias of the combined charges, vibrates, and this very asymmetric inertia displacements cause a weak attraction between dipoles.

    The mystery of gravity is long from over.

    There can be no greater disappointment and at times even insult to human intellect, than.........simplicity.
    Reply