In a few days, China will launch the Svom space mission (Space-based multi-band astronomical Variable Objects Monitor)the fruit of Franco-Chinese collaboration (*)) dedicated to the study of gamma-ray bursts, these fascinating astronomical phenomena resulting from the most distant stellar explosions. Svom will be launched on June 22, 2024 from the Xichang base, aboard a Long March 2C launcher. Its mission is planned to last three years with a possible extension of three additional years.
A window into the early Universe
The objective of this mission is to explore in depth gamma bursts, these lightninglightning of a brightnessbrightness exceptional, among the oldest and most distant events recorded in the cosmoscosmos. This light was sometimes emitted when the Universe was less than a billion years old, or 5 to 10% of its current age. By probing these ephemeral cosmic phenomena, Svom opens up the doorsdoors of a windowwindow temporal allowing us to dive into the primitive Universe, explore its first stars and analyze the stellar environment of these distant eras.
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Understanding the composition of the Universe over time
Before reaching us, the light from these gamma-ray bursts passes through several billionlight yearslight years, thus encoding crucial information on the history of the Universe and its evolution. These could thus give us indications on the element content of the Universe, the interstellar composition, and even the dynamics of the gasgas galactic as well as information on the galaxiesgalaxies hosts of these bursts.
Phenomena very difficult to observe due to the very short duration of gamma ray emission
However, the study of gamma-ray bursts remains a major challenge due to their brief durationduration ofemissionemission, ranging from fractions of a second to just a few tens of seconds. To meet this challenge, the Svom mission relies on an arsenal of four sophisticated instruments, designed to detect, locate and study them with great precision and responsiveness. We therefore count the telescopetelescope ECLAIRs, to detect and locate gamma bursts in the band of X-raysX-rays and gamma raysgamma rays bass energyenergythe MXT telescope for the observation of gamma bursts in the soft X-ray domain, the spectrometerspectrometer wide-field GRM gamma which will measure the spectrumspectrum at high energy of gamma-ray bursts as well as a telescope operating in the visible and very close range infraredinfraredwhich will detect and observe the emission of light produced immediately after a gamma-ray burst.
The brevity of the gamma-ray bursts requires a very complex strategy put in place for the Svom mission in order to collect data while avoiding downtime. For this, the instruments are quite simply technological jewels and the ECLAIRs telescope uses one of the softwaresoftware the most complex ever embarked on a space instrument which required six years of development at the CEA.
Finally, due to its unparalleled reactivity and its automated instruments, Svom can be used to observe transient cosmic phenomena, that is to say ephemeral objects or whose luminosity varies over time, such as supernovae or sources of gravitational waves.
*The mission is the result of a collaboration between the two national space agencies CNSA (China National Space Administration) and Cnes (National Center for Space Studies) with the main contributions of the CEA and the CNRS for France and the National Astronomical Observatory (NAONAO) and the Institute of physicalphysical Beijing High Energy Institute (IHEP) for China.
France and China go hunting for gamma rays with a space telescope
Article from Daniel ChrétienDaniel Chrétienpublished on 03/08/2023
The Franco-Chinese Svom mission is progressing well. The French instruments are ready to leave to be integrated into the small space telescopespace telescope Chinese. Takeoff is scheduled for December.
Svom (Space-based multi-band astronomical Variable Object Monitor) aims to capture gamma-ray bursts, an extreme event among the most extreme known in astrophysicsastrophysics. These are the signatures, in the form of flashesflashes, gigantic explosions. They are considered the brightest and richest elements since the Big Bang. The power released corresponds to more than a thousand billion sunssuns !
Rare events
At best, we could observe around ten per day. They are so bright that we can observe them beyond the borders of our Galaxy. However, it is very difficult to detect them because these bursts are random and unpredictable. They can come from supernovaesupernovae or shocks between massive objects such as black holesblack holes or some neutron starsneutron stars.
Gamma burst animation. © NASA
To detect a gamma burst, Svom is equipped with a monitormonitor consisting of three detectors to cover a large section of the sky. They are each positioned in a different direction, in order to be able to locate a burst. The information from this detector can supplement that of gravitational wavesgravitational waves from Earth (with the Ligo and Virgo instruments).
Once detected, the burst is then observed by three different telescopes. Two are provided under French project management: ECLAIRs (developed at the Institute for Research in Astrophysics and Planetology in Toulouse in partnership with the CEA and the University of Paris-Saclay), and MXT (CEA with British and German participation ). ECLAIRs observes in X-rays and soft gamma rays, MXT observes in X-rays with a narrower field of view. Finally, a visible light telescope (VT) will observe the light produced just after the burst.
Franco-Chinese collaboration
Cnes and the Chinese space agency had already collaborated on other missions. The one on Svom dates back to 2014. Cnes providing the main ECLAIRs and MXT telescopes, China provides the other telescope, the monitor, and the platform of the 930 kilo space telescope. A rocketrocket Long March 2C will place him in orbitorbit low ground.
Svom, the future gamma burst hunter, receives its sensors
Article from Remy DecourtRemy Decourtpublished on November 14, 2010.
Small satellite intended for the study of gamma-ray bursts, Svom is due to be launched in 2015. It will soon receive sensorssensors prototypes intended for the Eclairs telescope, the main payload of the satellite.
The result of a collaboration between France and China, the Svom satellite (Space based multi-band Variable Object Monitor) was built around the platform ProteusProteus of Cnes. Its development continues with the delivery of the first prototype sensors.
Produced by the Safran Electronics division of Sagem in its establishment in ValenceValencethese sensors detect X and gamma radiation, and each include 32 telluride detectors of cadmiumcadmium (CdTe). They will equip the Eclairs telescope, a wide-field instrument operating in the 4 to 300 keV range which will provide the positions of gamma-ray bursts in real time with a precision of less than 10 arc minutesarc minutes. All of these detectors will form a sensor with a useful surface area of 1,000 cm2.
Events associated with the formation of black holes
Svom will be launched in 2015 at an altitude of 625 kilometers and will operate for 3 years with a possible extension of its mission for another 3 years. It will have to observe more than 200 gamma-ray bursts, and will help us to better understand their nature and the formation of the first objects in the universe. After the Big BangBig Bang, these bursts are the most violent astrophysical phenomena known in the universe. They manifest themselves by very intense, variable and brief X-ray and gamma emissions: they last only from a few milliseconds to a few hours. If they remained enigmatic for a long time, the astrophysicistsastrophysicists today associate them withcollapsecollapse of a massive star in rapid rotation or at the coalescencecoalescence of two starsstars compact (neutron stars or black holes).
Svom has 4 telescopes operating in high energies, visible and infrared, manufactured by China and France. Another important device, the radio system UHFUHF which will be responsible for quickly providing the position of the observed bursts to the entire scientific community, within a few minutes.
To validly observe these gamma-ray bursts, which last so short a time, it is in fact essential to observe them over a wide range of wavelengthswavelengths and throughout their entire lifespan. It is therefore necessary to continue the study initiated on board the satellite by observations on the ground using larger and more efficient telescopes.
