Cosmology

Jan 25, 2024

ESA's Scientific Program Committee has adopted the LISA mission, giving the go-ahead for construction of the instrument and satellites. For the first time, LISA will observe the Universe through gravitational waves from space.

ISA (Laser Interferometer Space Antenna), the European Space Agency's large-scale mission to explore the Universe by observing the many sources of gravitational waves, was adopted on Thursday January 25 by ESA's Scientific Programs Committee, meaning that the concept and technology are recognized as sufficiently advanced for construction of the instrument and satellites to begin. Launch is scheduled for 2035.

More

Jun 12, 2023

DESI collaboration publishes observational data on nearly two million astrophysical objects

To study dark energy, the large Dark Energy Spectroscopic Instrument (DESI) will map over 40 million galaxies. Today, DESI has released its first data and is publishing 15 papers on the scientific study of these data.

The Universe is immensely big, and getting bigger all the time. To study dark energy, the mysterious force behind the accelerating expansion of our Universe, scientists are using the large Dark Energy Spectroscopic Instrument (DESI) survey to map over 40 million galaxies, quasars and stars. Today, the collaboration has released its first batch of data, with nearly 2 million astrophysical objects for researchers to study.

More

DESI collaboration publishes observational data on nearly two million astrophysical objects

May 11, 2023

Could the GRB221009A burst of October 9, 2022 be the most violent starburst of our millennium?

On October 9, 2022, at 13:16 and 59.99 seconds, a gamma-ray burst (GRB) dazzled almost all the X-ray and gamma ray detectors available at the time. Since their discovery, multi-wavelength telescopes in space and on the ground have continuously monitored these events. This outburst, named GRB221009A, shook the world community of astrophysicists, who have since been analysing it to understand the physical phenomena that triggered this most intense burst of energy in our history.

More

May 17, 2021

Desi starts its large spectroscopic survey for 5 years

After a particularly successful first campaign of tests and measurements, the Dark Energy Spectroscopic Instrument (DESI) has just successfully started its 5-year observing program.

After a particularly successful first campaign of tests and measurements, the Dark Energy Spectroscopic Instrument (DESI) has just successfully started its 5-year observing program. The international collaboration, under the lead of Berkeley Lab, has the ambitious goal to carry out the largest survey of galaxies and quasars. It will be used to draw the most accurate 3D map of the Universe and to elucidate the mystery of "dark energy".

More

Desi starts its large spectroscopic survey for 5 years

Jan 13, 2021

Building a giant 2D map of the Universe to prepare for DESI's 3D exploration

Nearly 200 researchers were involved in collecting, processing and assembling images of half the sky to prepare for the start of observations by DESI, the Dark Energy Spectroscopic Instrument, which aims to solve the mystery of dark energy. In order for DESI to begin its 5-year mission (2021-2026) to produce the largest 3D sky map ever made, researchers first needed a gigantic 2D map of the Universe.

More

Jul 20, 2020

The dark energy properties revealed over 11 billion years of the Universe expansion

The Sloan Digital Sky Survey (SDSS) published in July a complete analysis of the largest three-dimensional map of the Universe ever created, reconstructing the history of its expansion over a period of 11 billion years.

Dec 20, 2019

The net is tightening on the neutrinos of the cosmos...

A team from IRFU's Department of Particle Physics (DPhP) has just conducted the most accurate study to date of the mass of cosmic neutrinos, including both standard model neutrinos and sterile neutrinos contributing to dark matter. The researchers used the spectra of nearly 200,000 distant quasars measured by the Sloan Digital Sky Survey (SDSS) eBOSS project to map the distribution of hydrogen at very remote times in the history of our universe, ten to twelve billion years ago.

More

Apr 11, 2019

DESI moves to Kitt Peak

The Dark Energy Spectroscopic Instrument (DESI) is intended to make the spectroscopic survey of 35 million galaxies and quasars from 2020 onwards, to study precisely the properties of dark energy. Its installation, started in 2018, has recently entered a new phase with the reception and assembly of the first two spectrographs out of the 10 that the instrument will include.

More

Feb 25, 2019

When neutrinos encounter "baryonic acoustic oscillations"...

Neutrinos from the Big Bang have been traveling the Universe for more than 13 billion years. They are almost undetectable but their footprint on the formation of large structures in the Universe, such as galaxies, can be detected. For the first time, this trace of the "diffuse neutrino background" from the Big Bang on the "baryonic acoustic oscillations" (BAO) has been deduced from the survey of 1.2 million galaxies of the "Sloan Digital Sky Survey" (SDSS).

More

Feb 27, 2018

The brightest objects in the Universe in the onslaught of general relativity

More than twenty years after the discovery of the acceleration of the expansion of the Universe, the nature of the physical phenomenon at the origin of this acceleration, called "dark energy", is still unknown. The current model of cosmology is based on general relativity as a theory of gravitation and establishes a theoretical prediction for the quantity of galaxies that form at a given period of the Universe. This cosmological parameter is called the growth rate of cosmic structures.

More

The brightest objects in the Universe in the onslaught of general relativity

Jul 10, 2017

Probing Dark Matter in the Light of Quasars

Several decades after its discovery, dark matter remains enigmatic. Researchers from IRFU have tested three models of dark matter in which the formation of large structures was modeled using supercomputing. The reconstruction of large structures from observations of quasar spectra favors the hypothesis of a standard "cold" dark matter and sets some of the strongest constraints on these invisible masses.

Jun 13, 2017

A New Cosmic Mapping Reinforces Modern Cosmology

An international team from the Sloan Digital Sky Survey (SDSS) has carried out the first large-scale spectroscopic analysis of quasars, and was able to create a full 3D map of the universe and its large structures as it was 6 billion years ago. For now, the standard model of Cosmology, based upon Einstein's general theory of relativity, is confirmed.

Jan 30, 2017

DESI, the kick-off is given!

The Dark Energy Spectroscopic Instrument (Desi) will analyze the light emitted by 35 million galaxies and quasars at various times in the past of the Universe and up to 11 billion years to better understand dark energy. Its move into the construction phase in 2016 crowns several years of research and development that have resulted in a solid design and a credible observation strategy. Irfu, a partner in the project from the outset, has played a key role. A look back at a year that saw the project become a reality.

More

Jan 29, 2017

Is the Universe Homogeneous on a Large Scale?

The homogeneity of our universe is among the founding principles of cosmology—yet are we really sure that it is so? Until now, the main argument supporting the idea that it is homogeneous was based on a coherence test that implicitly used the homogeneity of the universe for its demonstration.

Apr 08, 2014

Astronomers at the Sloan Digital Sky Survey make the most accurate measurement to date of the rate of expansion of the universe

Astronomers at the Sloan Digital Sky Survey (SDSS) used 140,000 distant quasars to measure the rate of expansion of the Universe when it was only a quarter of its present age. This is the best measure of the rate of expansion at any time in the 13 billion years since the Big Bang. Researchers from Irfu (CEA) and CNRS played a major role in this discovery.

More

Division of Electronics, Detectors and Computing for Physics (DEDIP)

Institute of Research into the Fundamental Laws of the Universe