Showing posts with label cosmic microwave background (CMB). Show all posts
Showing posts with label cosmic microwave background (CMB). Show all posts

Monday, June 09, 2025

NASA’s Chandra Sees Surprisingly Strong Black Hole Jet at Cosmic “Noon”

A black hole has blasted out a surprisingly powerful jet in the distant universe, according to a study from NASA’s Chandra X-ray Observatory. X-ray: NASA/CXC/CfA/J. Maithil et al.; Illustration: NASA/CXC/SAO/M. Weiss; Image Processing: NASA/CXC/SAO/N. Wolk


black hole has blasted out a surprisingly powerful jet in the distant universe, according to a new study from NASA’s Chandra X-ray Observatory. This jet exists early enough in the cosmos that it is being illuminated by the leftover glow from the big bang itself.

Astronomers used Chandra and the Karl G. Jansky Very Large Array (VLA) to study this black hole and its jet at a period they call “cosmic noon,” which occurred about three billion years after the universe began. During this time most galaxies and supermassive black holes were growing faster than at any other time during the history of the universe.

The main graphic is an artist’s illustration showing material in a disk that is falling towards a supermassive black hole. A jet is blasting away from the black hole towards the upper right, as Chandra detected in the new study. The black hole is located 11.6 billion light-years from Earth when the cosmic microwave background (CMB), the leftover glow from the big bang, was much denser than it is now. As the electrons in the jets fly away from the black hole, they move through the sea of CMB radiation and collide with microwave photons. These collisions boost the energy of the photons up into the X-ray band (purple and white), allowing them to be detected by Chandra even at this great distance, which is shown in the inset.

Researchers, in fact, identified and then confirmed the existence of two different black holes with jets over 300,000 light-years long. The two black holes are 11.6 billion and 11.7 billion light-years away from Earth, respectively. Particles in one jet are moving at between 95% and 99% of the speed of light (called J1405+0415) and in the other at between 92% and 98% of the speed of light (J1610+1811). The jet from J1610+1811 is remarkably powerful, carrying roughly half as much energy as the intense light from hot gas orbiting the black hole.

The team was able to detect these jets despite their great distances and small separation from the bright, growing supermassive black holes — known as “quasars” — because of Chandra’s sharp X-ray vision, and because the CMB was much denser then than it is now, enhancing the energy boost described above.

When quasar jets approach the speed of light, Einstein’s theory of special relativity creates a dramatic brightening effect. Jets aimed toward Earth appear much brighter than those pointed away. The same brightness astronomers observe can come from vastly different combinations of speed and viewing angle. A jet racing at near-light speed but angled away from us can appear just as bright as a slower jet pointed directly at Earth.

The researchers developed a novel statistical method that finally cracked this challenge of separating effects of speed and of viewing angle. Their approach recognizes a fundamental bias: astronomers are more likely to discover jets pointed toward Earth simply because relativistic effects make them appear brightest. They incorporated this bias using a modified probability distribution, which accounts for how jets oriented at different angles are detected in surveys. Their method works by first using the physics of how jet particles scatter the CMB to determine the relationship between jet speed and viewing angle. Then, instead of assuming all angles are equally likely, they apply the relativistic selection effect: jets beamed toward us (smaller angles) are overrepresented in our catalogs. By running ten thousand simulations that match this biased distribution to their physical model, they could finally determine the most probable viewing angles: about 9 degrees for J1405+0415 and 11 degrees for J1610+1811.

These results were presented by Jaya Maithil (Center for Astrophysics | Harvard & Smithsonian) at the 246th meeting of the American Astronomical Society in Anchorage, AK, and are also being published in The Astrophysical Journal. A preprint is available here. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.




Visual Description

This release is supported by an artist’s illustration of a jet blasting away from a supermassive black hole.

The black hole sits near the center of the illustration. It resembles a black marble with a fine yellow outline. Surrounding the black hole is a swirling disk, resembling a dinner plate tilted to face our upper right. This disk comprises concentric rings of fiery swirls, dark orange near the outer edge, and bright yellow near the core.

Shooting out of the black hole are two streaky beams of silver and pale violet. One bright beam shoots up toward our upper right, and a second somewhat dimmer beam shoots in the opposite direction, down toward our lower left. These beams are encircled by long, fine, corkscrewing lines that resemble stretched springs.

This black hole is located 11.6 billion light-years from Earth, much earlier in the history of the universe. Near this black hole, the leftover glow from the big bang, known as the cosmic microwave background or CMB, is much denser than it is now. As the electrons in the jets blast away from the black hole, they move through the sea of CMB radiation. The electrons boost the energies of the CMB light into the X-ray band, allowing the jets to be detected by Chandra, even at this great distance.

Inset at our upper righthand corner is an X-ray image depicting this interaction. Here, a bright white circle is ringed with a band of glowing purple energy. The jet is the faint purple line shooting off that ring, aimed toward our upper right, with a blob of purple energy at its tip
.


News Media Contact

Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998

mwatzke@cfa.harvard.edu

Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034

lane.e.figueroa@nasa.gov


Tuesday, April 01, 2025

A New Cosmic Ruler: Measuring the Hubble Constant with Type II Supernovae

Figure 1: Type II supernova sample used for the Hubble constant measurement. The images show the host galaxies of the ten supernovae, with the explosion sites marked by red star symbols. The images are aligned with a redshift scale reflecting the relative distances of the supernovae from Earth. © MPA

Figure 2: Spectral fitting and the Hubble diagram for Type II supernovae. The top panels show two examples of spectral fits used to determine the supernova distances. By comparing observed spectra (black) with model predictions (colour), researchers can extract key physical properties and infer the intrinsic brightness, enabling a direct distance measurement. The bottom panel presents a Hubble diagram, where the measured luminosity distances of the supernovae are plotted against their redshifts. The data points represent individual spectral observations, meaning multiple measurements can exist for each supernova. The dashed black line represents the best-fit relationship between distance and redshift, and its slope is determined by the Hubble constant. The grey-shaded regions indicate the uncertainties for this fit (68% and 95% confidence intervals). The best-fit value for the Hubble constant and its 68% confidence interval are H₀ = 74.9 ± 1.9 km/s/Mpc. © MPA

Figure 3: Artist’s impression of the Hubble tension, showing the two different approaches to measuring the Hubble constant as two bridges that do not quite connect. The depicted early-Universe measurements yield an average value of 67.4 km/s/Mpc, the local measurements an average value of 73.0 km/s/Mpc. The new measurement from this study, based on Type II supernovae (orange), is completely independent of all other measurements and provides compelling support for the Hubble tension. The local route also includes results from various incarnations of the cosmic distance ladder, as well as other direct methods such as gravitational lensing and water masers. Image Credit: Original image by NOIRLab/NSF/AURA/J. da Silva, sourced from NOIRLab (CC BY 4.0), modified by S. Taubenberger.



The expansion rate of the Universe, quantified by the Hubble constant (H₀), remains one of the most debated quantities in cosmology. Measurements based on nearby objects yield a higher value than those inferred from observations of the early Universe—a discrepancy known as the "Hubble tension". Researchers at the Max Planck Institute for Astrophysics and their collaborators have now presented a new, independent determination of H₀ using Type II supernovae. By modeling the light from these exploding stars with advanced radiation transport techniques, they were able to directly measure distances without relying on the traditional distance ladder. The resulting H₀ value agrees with other local measurements and adds to the growing body of evidence for the Hubble tension, offering an important cross-check and a promising path toward resolving this cosmic puzzle.

One of the biggest puzzles in modern cosmology is the ongoing discrepancy in measurements of the Hubble constant (H₀) between local and early Universe probes, known as the “Hubble tension”. Since H₀ describes the current expansion rate of the Universe, it is a local quantity and can only be directly measured using nearby objects. In contrast, methods based on the early Universe, such as those using the cosmic microwave background (CMB), do not measure H₀ directly. Instead, they infer its value by assuming a cosmological model to extrapolate from the conditions 13 billion years ago to today. The fact that these two approaches yield conflicting values—with local distance-ladder measurements giving a higher H₀ than early-Universe methods—suggests that our standard cosmological model may be incomplete, potentially pointing to new physics.

Researchers at the Max Planck Institute for Astrophysics (MPA) and their collaborators have explored an independent way of measuring H₀ using Type II supernovae (SNe II). Unlike traditional approaches, this method does not rely on the cosmic distance ladder, making it a powerful cross-check against existing techniques. Their results provide a new, highly precise measurement of H₀ and further contribute to the debate over the expansion rate of the Universe.

Determining the Hubble constant requires accurate measurements of distances to astronomical objects at different redshifts. The most widely used technique, the cosmic distance ladder, relies on several interconnected steps: distances to nearby objects (such as Cepheid variable stars) are used to calibrate further reaching indicators such as Type Ia supernovae (SNe Ia), which then serve as standard candles to measure distances to faraway galaxies.

However, the reliance on multiple steps introduces possible systematic uncertainties, and different teams report slightly different results. A direct measurement based on known physics offers a valuable complementary approach, as it is affected by different systematics and does not depend on empirical calibrations. This is where Type II supernovae provide an exciting alternative.

Type II supernovae occur when massive, hydrogen-rich stars explode at the end of their lives. While their brightness varies depending on factors such as temperature, expansion velocity, and chemical composition, it can be accurately predicted using radiation transport models. This allows researchers to determine their intrinsic luminosity and use them as distance indicators, independent of empirical calibration methods.

A critical step in this process is identifying the best-fitting model for each observed supernova. Key physical properties leave distinct imprints on the supernova spectrum: temperature shapes the overall continuum, expansion velocity sets the width of spectral lines via Doppler broadening, and chemical composition determines the strength of specific absorption and emission features. By systematically comparing observed spectra to simulated spectra from radiative transfer models, researchers can find the model that most accurately describes the supernova’s physical conditions. With such a well-matched model the intrinsic brightness—and thus the distance—can be precisely determined.

To make this process efficient, the team used a spectral emulator, an advanced machine-learning tool trained on precomputed simulations. Instead of running time-intensive radiation transport calculations for every supernova, the emulator rapidly interpolates between models, allowing for fast and accurate spectral fitting.

The research team applied their spectral modeling approach to a sample of ten Type II supernovae at redshifts between 0.01 and 0.04, using publicly available data not specifically designed for distance measurements (Fig. 1). Despite the limitations of the dataset, their method yielded reliable distances. By constructing a Hubble diagram from these measurements (Fig. 2), they obtained an independent estimate of H₀: H₀ = 74.9 ± 1.9 km/s/Mpc

This value is consistent with most other local measurements, such as those from Cepheid-calibrated supernovae and supports the tension with early-Universe probes. The achieved precision is comparable to the most competitive techniques, demonstrating that Type II supernovae are a promising tool for cosmology (Fig. 3).

This study serves as a proof of concept, showing that Type II supernovae can provide precise and reliable distance measurements in the Hubble flow. Future work will focus on increasing the sample size and improving the accuracy of the technique by using dedicated observations. To this end, the researchers have assembled the adH0cc dataset (https://adh0cc.github.io/), a collection of Type II supernova observations from the ESO Very Large Telescope, specifically designed for precise distance measurements. This dataset will serve as a key resource for refining the method. By providing an independent check on the local determination of H₀, Type II supernovae help astrophysicists tackle one of the most pressing questions in cosmology today: Is the Hubble tension real, and if so, what does it tell us about the fundamental nature of the Universe?





Authors:

Christian Vogl
Postdoc
2297

cvogl@mpa-garching.mpg.de

Stefan Taubenberger
2019

tauben@mpa-garching.mpg.de

Wolfgang Hillebrandt
Emeritus Director


Original publication

Vogl, Christian; Taubenberger, Stefan; et al.
No rungs attached: A distance-ladder free determination of the Hubble constant through type II supernova spectral modelling
submitted to A&A

Friday, February 14, 2025

Gemini North Teams Up With LOFAR to Reveal Largest Radio Jet Ever Seen in the Early Universe

PR Image noirlab2506a
Artistic representation of the largest radio jet in the early Universe

PR Image noirlab2506b
Quasar J1601+3102

PR Image noirlab2506c
Quasar J1601+3102



Videos

Cosmoview Episode 95: Gemini North Teams Up with LOFAR to Reveal the Largest Radio Jet Ever Seen in the Early Universe
PR Video noirlab2506a
Cosmoview Episode 95: Gemini North Teams Up with LOFAR to Reveal the Largest Radio Jet Ever Seen in the Early Universe

Cosmoview Episode 95: Gemini North Teams Up with LOFAR to Reveal the Largest Radio Jet Ever Seen in the Early Universe
PR Video noirlab2506b
Cosmoview Episodio 95: Gemini Norte colabora con LOFAR para descubrir el Jet más grande del Universo temprano



The monster jet spans at least 200,000 light-years and formed when the Universe was less than 10% of its current age

Making use of the Gemini North telescope, one half of the International Gemini Observatory, funded in part by the U.S. National Science Foundation and operated by NSF NOIRLab, astronomers have characterized the largest-ever early-Universe radio jet. Historically, such large radio jets have remained elusive in the distant Universe. With these observations, astronomers have valuable new insights into when the first jets formed in the Universe and how they impacted the evolution of galaxies.

From decades of astronomical observations scientists know that most galaxies contain massive black holes at their centers. The gas and dust falling into these black holes liberates an enormous amount of energy as a result of friction, forming luminous galactic cores, called quasars, that expel jets of energetic matter. These jets can be detected with radio telescopes up to large distances. In our local Universe these radio jets are not uncommon, with a small fraction being found in nearby galaxies, but they have remained elusive in the distant, early Universe until now.

Using a combination of telescopes, astronomers have discovered a distant, two-lobed radio jet that spans an astonishing 200,000 light-years at least — twice the width of the Milky Way. This is the largest radio jet ever found this early in the history of the Universe [1]. The jet was first identified using the international Low Frequency Array (LOFAR) Telescope, a network of radio telescopes throughout Europe.

Follow-up observations in the near-infrared with the Gemini Near-Infrared Spectrograph (GNIRS), and in the optical with the Hobby Eberly Telescope, were obtained to paint a complete picture of the radio jet and the quasar producing it. These findings are crucial to gaining more insight into the timing and mechanisms behind the formation of the first large-scale jets in our Universe.

GNIRS is mounted on the Gemini North telescope, one half of the International Gemini Observatory, funded in part by the U.S. National Science Foundation (NSF) and operated by NSF NOIRlab.

“We were searching for quasars with strong radio jets in the early Universe, which helps us understand how and when the first jets are formed and how they impact the evolution of galaxies,” says Anniek Gloudemans, postdoctoral research fellow at NOIRLab and lead author of the paper presenting these results in The Astrophysical Journal Letters.

Determining the properties of the quasar, such as its mass and the rate at which it is consuming matter, is necessary for understanding its formation history. To measure these parameters the team looked for a specific wavelength of light emitted by quasars known as the MgII (magnesium) broad emission line. Normally, this signal appears in the ultraviolet wavelength range. However, owing to the expansion of the Universe, which causes the light emitted by the quasar to be ‘stretched’ to longer wavelengths, the magnesium signal arrives at Earth in the near-infrared wavelength range, where it is detectable with GNIRS.

The quasar, named J1601+3102, formed when the Universe was less than 1.2 billion years old — just 9% of its current age. While quasars can have masses billions of times greater than that of our Sun, this one is on the small side, weighing in at 450 million times the mass of the Sun. The double-sided jets are asymmetrical both in brightness and the distance they stretch from the quasar, indicating an extreme environment may be affecting them.

“Interestingly, the quasar powering this massive radio jet does not have an extreme black hole mass compared to other quasars,” says Gloudemans. “This seems to indicate that you don’t necessarily need an exceptionally massive black hole or accretion rate to generate such powerful jets in the early Universe.”

The previous dearth of large radio jets in the early Universe has been attributed to noise from the cosmic microwave background — the ever-present fog of microwave radiation left over from the Big Bang. This persistent background radiation normally diminishes the radio light of such distant objects.

“It’s only because this object is so extreme that we can observe it from Earth, even though it’s really far away,” says Gloudemans. “This object shows what we can discover by combining the power of multiple telescopes that operate at different wavelengths.”

“When we started looking at this object we were expecting the southern jet to just be an unrelated nearby source, and for most of it to be small. That made it quite surprising when the LOFAR image revealed large, detailed radio structures,” says Frits Sweijen, postdoctoral research associate at Durham University and co-author of the paper. “The nature of this distant source makes it difficult to detect at higher radio frequencies, demonstrating the power of LOFAR on its own and its synergies with other instruments.”

Scientists still have a multitude of questions about how radio-bright quasars like J1601+3102 differ from other quasars. It remains unclear what circumstances are necessary to create such powerful radio jets, or when the first radio jets in the Universe formed. Thanks to the collaborative power of Gemini North, LOFAR and the Hobby Eberly Telescope, we are one step closer to understanding the enigmatic early Universe.




Notes

[1] An example of a monster radio jet found in the nearby Universe is the 23 million-light-year-long jet, named Porphyrion, which was observed 6.3 billion years after the Big Bang.



More information

This research was presented in a paper titled “Monster radio jet (>66 kpc) observed in quasar at z ∼ 5” to appear in The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/ad9609

The team is composed of Anniek J. Gloudemans (NSF NOIRLab, International Gemini Observatory), Frits Sweijen (Durham University), Leah K. Morabito (Durham University), Emanuele Paolo Farina (NSF NOIRLab, International Gemini Observatory), Kenneth J. Duncan (Royal Observatory, Edinburgh), Yuichi Harikane (University of Tokyo), Huub J. A. Röttgering (Leiden University), Aayush Saxena (University of Oxford, Durham University), and Jan-Torge Schindler (University of Hamburg).

NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.

The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.



Links




Contacts:

Anniek Gloudemans
Postdoctoral research fellow
NSF NOIRLab / International Gemini Observatory
Email: anniek.gloudemans@noirlab.edu

Frits Sweijen
Postdoctoral research associate
Durham University
Email: frits.sweijen@durham.ac.uk

Josie Fenske
Jr. Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu


Tuesday, November 14, 2023

Astronomers carry out largest ever cosmological computer simulation


The background image shows the present-day distribution of matter in a slice through the largest FLAMINGO simulation, which is a cubic volume of 2.8 Gpc (9.1 billion light years) on a side. The luminosity of the background image gives the present-day distribution of dark matter, while the colour encodes the distribution of neutrinos. The insets show three consecutive zooms centred on the most massive cluster of galaxies; in order, these show the gas temperature, the dark matter density, and a virtual X-ray observation (from Figure 1 from Schaye et al. 2023).Credit:Josh Borrow, the FLAMINGO team and the Virgo Consortium.
https://ras.ac.uk/media/1463

Licence type: Attribution (CC BY 4.0)



An international team of astronomers has carried out what is believed to be the largest ever cosmological computer simulation, tracking not only dark but also ordinary matter (such as planets, stars and galaxies), giving us a glimpse into how our Universe may have evolved. The FLAMINGO simulations calculate the evolution of all components of the universe - ordinary matter, dark matter, and dark energy - according to the laws of physics. As the simulation progresses, virtual galaxies and clusters of galaxies emerge. Three papers have been published in Monthly Notices of the Royal Astronomical Society: one describing the methods, another presenting the simulations and the third examining how well the simulations reproduce the large-scale structure of the Universe.

Facilities such as the Euclid Space Telescope recently launched by the European Space Agency (ESA) and NASA’s JWST collect impressive amounts of data on galaxies, quasars, and stars. Simulations such as FLAMINGO play a key role in the scientific interpretation of the data by connecting predictions from theories of our universe to the observed data.

According to the theory, the properties of our entire universe are set by a few numbers called 'cosmological parameters' (six of them in the simplest version of the theory). The values of these parameters can be measured very precisely in various ways. One of these methods relies on the properties of the cosmic microwave background (CMB), a faint background glow left over from the early Universe. However, these values do not match those measured by other techniques that rely on the way in which the gravitational force of galaxies bends light (lensing). These ‘tensions’ could signal the demise of the standard model of cosmology – the cold dark matter model.

The computer simulations may be able to reveal the cause of these tensions because they can inform scientists about possible biases (systematic errors) in the measurements. If none of these prove sufficient to explain away the tensions, the theory will be in real trouble.

So far, the computer simulations used to compare to the observations only track cold dark matter. “Although the dark matter dominates gravity, the contribution of ordinary matter can no longer be neglected,” says research leader Joop Schaye (Leiden University), “since that contribution could be similar to the deviations between the models and the observations.”

The first results show that both neutrinos and ordinary matter are essential for making accurate predictions, but do not eliminate the tensions between the different cosmological observations.

Simulations that also track ordinary, baryonic matter (also known as baryonic matter) are much more challenging and require much more computing power. This is because ordinary matter - which makes up only sixteen per cent of all matter in the universe - feels not only gravity but also gas pressure, which can cause matter to be blown out of galaxies by active black holes and supernovae far into intergalactic space. The strength of these intergalactic winds depends on explosions in the interstellar medium and is very difficult to predict. On top of this, the contribution of neutrinos, subatomic particles of very small but not precisely known mass, is also important but their motion has not been simulated so far.

The astronomers have completed a series of computer simulations tracking structure formation in dark matter, ordinary matter, and neutrinos. PhD student Roi Kugel (Leiden University) explains: “The effect of galactic winds was calibrated using machine learning, by comparing the predictions of lots of different simulations of relatively small volumes with the observed masses of galaxies and the distribution of gas in clusters of galaxies.”

The researchers simulated the model that best describes the calibration observations with a supercomputer in different cosmic volumes and at different resolutions. In addition, they varied the parameters of the model, including the strength of galactic winds, the mass of neutrinos, and the cosmological parameters in simulations of slightly smaller but still large volumes.

The largest simulation uses 300 billion resolution elements (particles with the mass of a small galaxy) in a cubic volume with edges of ten billion light years. This is believed to be the largest cosmological computer simulation with ordinary matter ever completed. Matthieu Schaller (Leiden University): “To make this simulation possible, we developed a new code, SWIFT, which efficiently distributes the computational work over 30 thousand CPUs.”

The FLAMINGO simulations open a new virtual window on the universe that will help make the most of cosmological observations. In addition, the large amount of (virtual) data creates opportunities to make new theoretical discoveries and to test new data analysis techniques, including machine learning. Using machine learning, astronomers can then make predictions for random virtual universes. By comparing these with large-scale structure observations, they can measure the values of cosmological parameters. Moreover, they can measure the corresponding uncertainties by comparing with observations that constrain the effect of galactic winds.

Submitted by Robert Masse




Media contacts:

Leighton Kitson
Communications and Engagement Manager (External)
Durham University
Tel: +44(0)191 334 8623

leighton.kitson@durham.ac.uk

Marieke Baan
Head of Communications
Netherlands Research School for Astronomy NOVA
Mob: +31614322627

H.M.Baan@uva.nl

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877699

press@ras.ac.uk



Science contacts:

Prof. Dr Joop Schaye, Leiden Observatory, Leiden University

schaye@strw.leidenuniv.nl

Roi Kugel, PhD candidate at Leiden Observatory, Leiden University
kugel@strw.leidenuniv.nl

Dr Matthieu Schaller, Assistant Professor at Leiden Observatory, Leiden University
schaller@strw.leidenuniv.nl

Prof. Dr Ian McCarthy, Liverpool John Moores University
I.G.McCarthy@ljmu.ac.uk



Further information

FLAMINGO is a project of the VIRGO consortium for cosmological supercomputer simulations. The acronym stands for Full-hydro Large-scale structure simulations with All-sky Mapping for the Interpretation of Next Generation Observations. The FLAMINGO team is led by Joop Schaye (Leiden University) and within the team, scientists mainly from the Netherlands and the UK collaborate. The computer simulations were carried out with the DiRAC COSMA8 computer in Durham, UK.

FLAMINGO project website with images, videos, and interactive visualisations.

The FLAMINGO project: cosmological hydrodynamical simulations for large-scale structure and galaxy cluster surveys”, J. Schaye et al., Monthly Notices of the Royal Astronomical Society, 2023.

FLAMINGO: Calibrating large cosmological hydrodynamical simulations with machine learning”, R. Kugel et al, Monthly Notices of the Royal Astronomical Society, 2023.

The FLAMINGO project: revisiting the S8 tension and the role of baryonic physics”, I. McCarthy et al., Monthly Notices of the Royal Astronomical Society, 2023.



Notes for editors

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.


Wednesday, August 16, 2023

A New Way to Constrain Dark Energy


This ultraviolet mosaic of our galactic neighbor, the Andromeda Galaxy, is constructed from observations by NASA's Swift Observatory. Credit:
NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)

The cosmological constant, once rued by Einstein as his greatest blunder, is back in style. Researchers have used an entirely new method to determine the value of this constant — thought to be related to dark energy — using a galaxy in our cosmic backyard.


An image of anisotropies in the cosmic microwave background. The Planck satellite studied the cosmic microwave background to measure several important cosmological parameters. Credit:
ESA and the Planck Collaboration

Accounting for Acceleration

Our universe is expanding, and that expansion is accelerating, propelled by a mysterious quantity known as dark energy. Many researchers suspect that dark energy is an explanation for the cosmological constant, a quantity tacked onto the equations of Einstein’s theory of gravity. Initially included as a way to make the equations describe a static, non-expanding universe, Einstein scrapped the constant when the universe was revealed to be expanding. With the discovery that this expansion is actually accelerating, the cosmological constant is back in vogue, but with a new purpose.

Researchers have devised a number of ways to measure quantities relevant to the cosmological constant. For example, the Planck mission mapped the tiny imperfections and non-uniformities in the cosmic microwave background — the oldest light in the universe — to measure the cosmological constant on a global scale. But as with all active areas of research, it’s important to make measurements in multiple ways to test our theories from all angles. How might we probe the cosmological constant on an entirely different scale?


An illustration of the Local Group of galaxies, which contains the Milky Way and Andromeda, as well as some of its near neighbors. Click to enlarge. Credit:
Antonio Ciccolella; CC BY 4.0

Local Solutions to Global Questions

David Benisty, Anne-Christine Davis, and Wyn Evans (University of Cambridge) used pairs of galaxies locked in a gravitational dance to place constraints on the value of the cosmological constant. Their method hinges on the fact that the fabric of spacetime, from the space between the stars to the gaps between galaxies, is expanding under the influence of dark energy. This means that encoded within the orbital motions of any gravitationally bound galaxy pair is the subtle pressure of dark energy, forcing the galaxies apart as gravity pulls them together.

Benisty and collaborators analytically solved the two-body problem that describes the orbits of the Milky Way and its most massive neighbor, Andromeda, and accounts for the repulsive influence of dark energy. In doing so, they constrained the value of the cosmological constant over a few million light-years — a much smaller scale than the Planck mission, which drew its conclusions from the cosmic microwave background that suffuses the entire sky.


Constraints on the cosmological constant, Λ, compared to the constraints determined from Planck data. Future measurements, such as with JWST, are anticipated to greatly improve the constraint placed by the binary galaxy method. Credit: Adapted from
Benisty et al. 2023

Upper Limits and Other Applications

The team’s findings agreed with the results from the Planck mission, finding an upper limit on the value of the cosmological constant equal to 5.44 times the value measured by Planck. While the constraint is not particularly stringent, Benisty and coauthors anticipate that more precise data will allow them to narrow the constraint in the future. In particular, stellar positions measured by JWST will improve our estimates of Andromeda’s mass, which is one of the largest sources of uncertainty.

Benisty and collaborators also used their method to place constraints on other theories of gravity. While these constraints were less restrictive than those placed on the cosmological constant, the technique is still valuable as it constrains modified gravity on scales of millions of light-years rather than the solar-system-sized scales from previous work.

Citation

“Constraining Dark Energy from the Local Group Dynamics,” David Benisty et al 2023 ApJL 953 L2. doi:10.3847/2041-8213/ace90b

Thursday, January 26, 2023

Astronomers create new microwave map of the Milky Way and beyond


Colour shows the polarized microwave emission measured by QUIJOTE. The pattern of lines superposed shows the direction of the magnetic field lines. Credit: The QUIJOTE Collaboration


An international team of scientists have successfully mapped the magnetic field of our galaxy, the Milky Way, using telescopes that observe the sky in the microwave range. The new research is published in Monthly Notices of the Royal Astronomical Society.

The team used the QUIJOTE (Q-U-I JOint TEnerife) Collaboration, sited at the Teide Observatory on Tenerife in the Canary Islands. This comprises two 2.5 m diameter telescopes, which observe the sky in the microwave part of the electromagnetic spectrum.

Led by the Instituto de Astrofísica de Canarias (IAC), the mapping began in 2012. Almost a decade later, the Collaboration has presented a series of 6 scientific articles, giving the most accurate description to date of the polarization of the emission of the Milky Way at microwave wavelengths. Polarization is a property of transverse waves such as light waves that specifies the direction of the oscillations of the waves and signifies the presence of a magnetic field.

The studies complement earlier space missions dedicated to the study of the cosmic microwave background radiation (CMB), the fossil radiation left behind by the Big Bang, which gave a detailed insight into the early history of the cosmos.

As well as mapping the magnetic structure of the Milky Way, the QUIJOTE data has also proved useful in other scenarios. The new data are also a unique tool for studying the anomalous microwave emission (AME), a type of emission first detected 25 years ago. AME is thought to be produced by the rotation of very small particles of dust in the interstellar medium, which tend to be oriented by the presence of the galactic magnetic field.

The new results allowed the team to obtain information about the structure of the magnetic field of the Milky Way, as well as helping to understand the energetic processes which took place close to the birth of the Universe. To measure signals from that time, scientists need to first eliminate the veil of emission associated with our own Galaxy. The new maps provided by QUIJOTE do just that, allowing us to better understand these elusive signals from the wider Universe.

The maps from QUIJOTE have also permitted the study of a recently detected excess of microwave emission from the centre of our Galaxy. The origin of this emission is currently unknown, but it could be connected to the decay processes of dark matter particles. With QUIJOTE, the team have confirmed the existence of this excess of radiation, and have found some evidence that it could be polarized.

Finally, the new maps from QUIJOTE have permitted the systematic study of over 700 sources of emission in radio and microwaves, of both Galactic and extragalactic origin, meaning that the data is helping scientists to decipher signals coming from beyond our galaxy, including the cosmic microwave background radiation.

“These new maps give a detailed description in a new frequency range, from 10 to 40 GHz, complementing those from space missions such as Planck and WMAP”, comments José Alberto Rubiño, lead scientist of the QUIJOTE Collaboration. “We have characterized the synchrotron emission from our Galaxy with unprecedented accuracy. This radiation is the result of the emission by charged particles moving at velocities close to that of light within the Galactic magnetic field. These maps, the result of almost 9,000 hours of observation, are a unique tool for studying magnetism in the universe” he adds.

“One of the most interesting results we have found is that the polarized synchrotron emission from our Galaxy is much more variable than had been thought” comments Elena de la Hoz, a researcher at the Instituto de Física de Cantabria (IFCA). “The results we have obtained are a reference to help future experiments make reliable detections of the CMB signal” she adds.

“Scientific evidence suggests that the Universe went through a phase of rapid expansion, called inflation, a fraction of a second after the Big Bang. If this is correct, we would expect to find some observable consequences when we study the polarization of the cosmic microwave background. Measuring those expected features is difficult, because they are small in amplitude, but also because they are less bright than the polarized emission from our own galaxy.” notes Rubiño, “However, if we finally measure them, we will have indirect information of the physical conditions in the very early stages of our Universe, when the energy scales were much higher than those that we can access or study from the ground. This has enormous implications for our understanding of fundamental physics.”

“The maps from QUIJOTE have also permitted the study of the microwave emission from the centre of our Galaxy. Recently an excess of microwave emission has been detected from this region, whose origin is unknown, but whose origin could be connected to the decay processes of dark matter particles. With QUIJOTE we have confirmed the existence of this excess of radiation, and have found some evidence that it could be polarized” comments Federica Guidi, a researcher at the Institut d'Astrophysique de Paris (IAP, Francia).




Media contacts:

Gurjeet Kahlon
Royal Astronomical Society
Mob: +44 (0)7802 877700

press@ras.ac.uk

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877699

press@ras.ac.uk

Science Contacts:

Professor Jose Alberto Rubino-Martin
Institute of Astrophysics of the Canary Islands

jalberto@iac.es

Dr Denis Tramonte
Purple Mountain Observatory

tramonte@pmo.ac.cn

Dr Federica Guidi
Paris Institute of Astrophysics

federica.guidi@iap.fr

Dr Frederick Poidevin
Institute of Astrophysics of the Canary Islands

fpoidevin@iac.es

Elena de la Hoz
The Institute of Physics of Cantabria/Unican

delahoz@ifca.unican.es

Dr Diego Herranz
The Institute of Physics of Cantabria

herranz@ifca.unican.es



Further information

The QUIJOTE (Q-U-I JOint TEnerife) CMB Experiment is a scientific collaboration between the Instituto de Astrofísica de Canarias (Tenerife, Spain), the Instituto de Física de Cantabria (Santander, Spain), the Departamento de Ingenieria de COMunicaciones (Santander, Spain), the Jodrell Bank Observatory (Manchester, UK), the Cavendish Laboratory (Cambridge, UK), and the IDOM company (Spain). It started operations in November 2012, and it consists in two telescopes and three instruments dedicated to measure the polarization of the microwave sky in the frequency range between 10 GHz and 40GHz, and at angular scales of one degree.

The work appears in ‘
QUIJOTE scientific results – IV. A northern sky survey in intensity and polarization at 10–20 GHz with the Multi-Frequency Instrument’, Rubiño-Martin et al., published in Monthly Notices of the Royal Astronomical Society, in press.

The press release includes information obtained from 5 other papers:
Notes for editors

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.


Tuesday, August 02, 2022

Scientists Reveal Distribution of Dark Matter around Galaxies 12 billion Years Ago - Further Back than Ever Before


Figure 1: Conceptual image of this research. Distribution of invisible "dark matter" was investigated by combining the cosmic microwave background (CMB) and the HSC-SSP images. Credit: Reiko Matsushita (Nagoya University)

How do we see something that happened so long ago? Because of the finite speed of light, we see distant galaxies not as they are today, but rather as they were billions of years in the past. But even more challenging, how do we see something like dark matter, that by its nature does not emit light? Consider a very distant source galaxy, even further away than the galaxy whose dark matter one wants to investigate. The gravitational pull of the foreground galaxy, including its dark matter, distorts the surrounding space and time, as predicted by Einstein’s theory of General Relativity. As the light from the source galaxy travels through this distortion, it bends, changing the apparent shape of the galaxy in the sky. The greater the amount of dark matter, the greater the distortion. Thus, scientists can measure the amount of dark matter around the foreground galaxy (the "lens" galaxy) from the distortion.

However, at this point, scientists encounter a problem. The galaxies in the deepest reaches of the Universe are incredibly faint. As a result, the further away from Earth you look, the less effective this technique becomes. The lensing distortion is subtle and difficult to detect in most cases, so one needs many background galaxies to detect the signal. Most previous studies remained stuck at the same limits. Unable to detect enough distant source galaxies to measure the distortion, they could only analyze dark matter from no further back than 8-10 billion years ago. These limitations left open the question about the distribution of dark matter between this time and 13.7 billion years ago, around the beginnings of our Universe.

To overcome these challenges and observe dark matter in the furthest reaches of the Universe, a research team led by Nagoya University’s Hironao Miyatake, in collaboration with the University of Tokyo, National Astronomical Observatory of Japan, and Princeton University, used a different source of background light, the microwaves released from the Big Bang itself.

How did they do this? First, using data from the observations of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), the team identified 1.5 million lens galaxies using visible light, selected to be seen 12 billion years ago. Next, to overcome the lack of galaxy light even further away, they employed microwaves from the cosmic microwave background (CMB), the radiation residue from the Big Bang. Using microwaves observed by the European Space Agency’s Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves.

"Look at dark matter around distant galaxies?" asks Professor Masami Ouchi of the National Astronomical Observatory of Japan and the University of Tokyo, who made many of the observations. "It was a crazy idea. No one realized we could do this. But after I gave a talk about a large distant galaxy sample, Hironao came to me and said it may be possible to look at dark matter around these galaxies with the CMB."

"Most researchers use source galaxies to measure dark matter distribution from the present to eight billion years ago", adds Assistant Professor Yuichi Harikane of the Institute for Cosmic Ray Research, University of Tokyo. "However, we could look further back into the past because we used the more distant CMB to measure dark matter. For the first time, we were measuring dark matter from almost the earliest moments of the Universe."

After a preliminary analysis, the researchers soon realized they had a large enough sample to detect the distribution of dark matter. Combining the large distant galaxy sample and the lensing distortions in the CMB, they detected dark matter even further back in time, from 12 billion years ago. This is only 1.7 billion years after the beginning of the Universe, and thus these galaxies are seen soon after they first formed.

"I was happy that we opened a new window into that era," Miyatake says. "12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well." Galaxy clusters consist of 100-1000 galaxies bound by gravity with large amounts of dark matter.

"This result gives a very consistent picture of galaxies and their evolution, as well as the dark matter in and around galaxies, and how this picture evolves with time," says Neta Bahcall, Eugene Higgins Professor of Astronomy, professor of astrophysical sciences, and director of undergraduate studies at Princeton University.

One of the most exciting of the researchers’ findings was related to the clumpiness of the dark matter. According to the standard theory of cosmology, the Lambda-CDM (Cold Dark Matter) model, subtle fluctuations in the CMB form pools of densely packed matter by attracting surrounding matter through gravity. This creates inhomogeneous clumps that form stars and galaxies in these dense regions. The group’s findings suggest that their clumpiness measurement was lower than predicted by the Lambda-CDM model. Miyatake is excited about the possibilities. "Our finding is still uncertain", he says. "But if it is true, it would suggest that the entire model is flawed as you go further back in time. This is exciting, because it could suggest – if the result holds after the uncertainties are reduced – an improvement of the model that may give insight into the nature of dark matter itself."

This study used data available from existing telescopes, including Planck and the Subaru Telescope. The group has only reviewed a third of the HSC-SSP data. The next step will be to analyze the entire data set, which should allow for a more precise measurement of the dark matter distribution. In the future, the team expects to use an advanced data set like the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) to explore more of the earliest parts of space. "LSST will allow us to observe half the sky," Harikane says. "I don’t see any reason we couldn’t see the dark matter distribution 13 billion years ago next."

These results appeared as Miyatake et al. "First Identification of a CMB Lensing Signal Produced by 1.5 Million Galaxies at z∼4: Constraints on Matter Density Fluctuations at High Redshift" in Physical Review Letters on August 1, 2022.



Relevant Links


Wednesday, June 01, 2022

New analysis strengthens the hint of new physics in polarized radiation from the early Universe


Fig.1 - Temperature fluctuations (color) and polarization (lines) of the CMB on a small patch of sky extracted from the full-sky map of the Planck mission. The lengths and orientations of the lines indicate the polarization strengths and directions, respectively. Credit: Planck Collaboration. A&A. 641, A1 (2020). 


Fig.2 - The emission of the CMB is polarized at the origin (left circle), where the black lines indicate the two possible orientations of the E mode. When the plane of linear polarization (orange lines) rotates by an angle β as the CMB photons travel to reach us today (right circle), the polarization pattern changes and might produce B modes (black lines).   Credit: Yuto Minami


Fig.3 - The observed EB correlation (black points and error bars in the upper panel) and residuals with respect to the best-fitting model (lower panel) for various angular scales. The horizontal axis shows the multipole l, which corresponds to the angular size of 180/l degrees in the sky. The blue and red shaded areas show the 68% confidence intervals for the cosmic birefringence and instrumental polarization contributions, respectively. The thick green solid line shows the total best-fitting model.  Credit: MPA/University of Oslo

Photons of the cosmic microwave background (CMB), the afterglow of the primordial fireball Universe, are linearly polarized (Figure 1). This pattern can be used to search for new physics violating “parity symmetry” – the symmetry of the laws of physics under an inversion of spatial coordinates. For example, electromagnetism works the same way whether one is in the original system or in a mirrored system with all spatial coordinates flipped. A violation of parity symmetry has only been observed in the weak interaction of the standard model of elementary particles and fields – so far. Can the Universe also violate parity symmetry?

The current cosmological model requires new physics beyond the standard model, such as dark matter and dark energy. These may be made of “pseudoscalar fields”, whose signs change under an inversion of the spatial coordinates. In particle physics, the concept of a pseudoscalar sounds familiar. For example, the particle ‘pion’ is a pseudoscalar, and a neutral pion decays into two photons via a parity-violating interaction in the standard model. This interaction can also rotate the plane of linear polarization of photons.

If the potential new pseudoscalars responsible for dark matter and dark energy interact with photons in a similar fashion, the plane of CMB polarization should have rotated as the CMB photons have been traveling for more than 13 billion years (Figure 2). This phenomenon is called “cosmic birefringence” because it resembles birefringence of photons in a crystal. Space filled with pseudoscalar dark matter and dark energy behaves as if it were a birefringent material! Discovery of cosmic birefringence therefore has profound implications for the fundamental physics behind dark matter, dark energy, and even quantum gravity.

The pattern of linear polarization can be decomposed into eigenstates of parity, called E and B modes (see also Fig. 2) . The E modes do not change sign under inversion of the spatial coordinates, whereas the B modes do. The cross-correlation between the two fields, the so-called “EB correlation”, vanishes if parity symmetry is respected. Therefore, one can search for new physics violating parity symmetry by measuring the EB correlation of the CMB. The previous analysis of the EB correlation in the Planck satellite’s polarization data revealed a tantalizing hint of cosmic birefringence with 99.2% confidence level (see this 2020 MPA Press Release), finding that the plane of linear polarization of the CMB was rotated by an angle β = 0.35 ± 0.14 degrees. This result was based on the Planck satellite’s high-frequency instrument (HFI) data from the Public Release 3 at frequencies higher than 100 GHz.

Now, the international team led by MPA director Eiichiro Komatsu used more CMB data, including the latest reprocessing of the Planck HFI data from Public Release 4 as well as low-frequency data from Planck’s low-frequency instrument (LFI) and WMAP at frequencies lower than 100 GHz. The combined dataset covers a wide range of frequencies from 23 to 353 GHz. The team also improved the analysis method by considering how interstellar dust grains in the Milky Way might impact the EB correlation of the polarization. They found an improved result, β = 0.34 ± 0.09 degrees, which excludes β=0 at 99.987% confidence level. The observed EB correlation is shown in Figure 3. The measured angle β is independent of frequencies and robust against the fraction of sky used for the analysis.

Although suggestive, a greater statistical significance, or a confidence level of 99.99995%, is required to claim a discovery of new physics. This could be achieved in the n



Author:

Eiichiro Komatsu
Director
2208
komatsu@mpa-garching.mpg.de

Original publications:

1. Patricia Diego-Palazuelos et al.
Cosmic Birefringence from the Planck Data Release 4
Phys. Rev. Lett. 128, 091302 – Published 1 March 2022

Source / DOI

2. Eiichiro Komatsu
New Physics from the Polarized Light of the Cosmic Microwave Background
Nat Rev Phys (2022).

DOI

3. Johannes Røsok Eskilt, Eiichiro Komatsu
Improved Constraints on Cosmic Birefringence from the WMAP and Planck Cosmic Microwave Background Polarization Data

Friday, May 20, 2022

A New Way to Probe the Early Universe

Simulated dark matter halo around a galaxy
Credit:
Wikipedia user Cosmo0

Astronomers have long sought to probe deep into our universe’s early history. What was the nature of matter back then? How did small galactic seeds grow into the gas-siphoning monsters we see today, and what was the nature of the mysterious substance that weighs down their halos yet eludes our earthly detectors? A team of astronomers may have uncovered a new tool that will allow us to probe this mysterious matter on smaller scales than ever before.


The Hubble eXtreme Deep Field, which shows galaxies from when the universe was just 500 million years old. Credit:
NASA, ESA, G. Illingworth, D. Magee, and P. Oesch, R. Bouwens, and the HUDF09 Team

Peering Back into the Universe’s History

One of the key tasks of modern astronomy has been to understand the early universe and how it evolved to get to the state it’s in today. The Hubble Space Telescope took us back to when the universe was just 500 million years old, and the Planck mission allowed us to peer back at the universe when it was just 380,000 years old, using the cosmic microwave background radiation (CMB) (light from the very early universe that’s been stretched to the microwave regime as the universe has expanded). One of the keys to understanding the early universe is understanding how both ordinary matter and dark matter behaved at this time.

A clue to how dark matter acts on small scales might be found in the dark matter halos surrounding galaxies in the early universe. These dark matter halos were much less massive than those that surround galaxies today, so probing these halos in the early universe would provide us with a new window to look at dark matter on smaller scales and could help us understand the nature of this mysterious substance that pervades our cosmos.


Different areas probed by different experiments, showing redshift against wavenumber, which characterizes the spatial scale explored with the measurements. Credit: Sabti et al. 2022

Probing Dark Matter on Small Scales

A group of scientists led by Nashwan Sabti from King’s College London has used a decade of observations from the Hubble Space Telescope to study dark matter at very small scales, looking at distant galaxies and their halos using a method complementary to the range of local probes and the CMB. The team first determined the ultraviolet galaxy luminosity function (UV LF), which captures the abundance of galaxies as a function of their UV luminosity. Because the UV LF is dependent on the mass distribution of dark matter halos, this technique allowed the authors to indirectly probe how dark matter is distributed on different scales during this early period in the universe’s history, revealing clues as to how the early structure of our universe formed and evolved.


Power spectrum as a function of wavenumber k for seven different works. Wavenumber is a measure of the spatial scale, and the matter power spectrum indicates what the matter density perturbations look like on any given scale. The results of this study (black crosses) are plotted along with previous measurements, showing that this work probes smaller scales (larger k) than any other experiment has before. Credit: Sabti et al. 2022


Using the Power of a Wide Range of Measurements

The authors’ UV LF measurements cover a wide range, from when the universe was 48 million years old all the way up to 156 million years old, and probe scales beyond what the CMB allows us to explore. The authors model the resulting matter power spectrum — a measure of how matter clusters on different spatial scales — with different parameters to test a range of theoretical models describing dark matter. The team found that their modeled power spectra were consistent with the theoretical predictions of the lambda cold dark matter model of cosmology (the standard model of the universe) up to a certain point. The power spectra disfavor other models, such as the warm dark matter model, which doesn’t predict structure consistent with what the team found on small scales.

These new results show that measuring the UV LF is a unique, powerful technique for probing the nature of dark matter. The newly launched JWST and the Nancy Grace Roman Space Telescope, which is set to launch in mid-2027, will observe galaxies farther back in the universe’s history and probe dark matter halos on smaller scales, making this an exciting time for dark matter astronomers!

Citation

“New Roads to the Small-scale Universe: Measurements of the Clustering of Matter with the High-redshift UV Galaxy Luminosity Function,” Nashwan Sabti et al 2022 ApJL 928 L20. doi:10.3847/2041-8213/ac5e9c