Tag

Cosmology

All articles tagged with #cosmology

science22 hours ago•18 min saved

Sizing the Cosmos: How the Observable Universe Expands Through Time

By applying the Friedmann equations—relating the expansion rate to the Universe's energy content (radiation, matter, dark energy) and curvature—cosmologists compute the observable Universe's size at any epoch. With current measurements of the Hubble constant and energy fractions, the present horizon is about 46 billion light-years across, and its past growth traces radiation-dominated, then matter-dominated, and now dark-energy–dominated expansion, yielding precise milestones for when the Universe reached fractions of its current size.

via Big Think|

#cosmology #dark-energy #friedmann-equations

science4 days ago•16 min saved

Cosmic Isotropy Remains Intact as DESI Anomaly Fades with Proper Corrections

A claimed anisotropy in the DESI galaxy survey is shown to be an artifact from not accounting for redshift-space distortions. When comoving distances are used and distortions corrected, the data align with a homogeneous, isotropic universe, reaffirming the cosmological principle and the standard model of cosmology.

via Big Think|

#cosmology #desi #isotropy

space5 days ago•6 min saved

Cosmic Web Persists Across Vast Scales, Challenging Uniformity

A Nature study analyzing 47 million galaxies from the DESI survey finds coherent patterns in the cosmic web extending across billions of light-years, suggesting the universe may not be perfectly homogeneous or isotropic on the largest scales. The result challenges a key cosmological assumption and could prompt revisions to models of dark matter, gravity, and structure formation, though independent replication with larger datasets is needed before firm conclusions.

via WIRED|

#astronomy #cosmic-web #cosmology

science5 days ago•11 min saved

Dark Matter’s Hidden Particle Puzzle: Gravity Speaks, Detectors Silence

Despite four decades of ultra-sensitive searches—from deep underground xenon detectors (like LZ) to space-based instruments and colliders—no direct dark matter particle has been observed. Gravitational evidence from galaxy rotations, merging clusters, and the cosmic microwave background confirms dark matter’s dominance, but its particle nature remains elusive. Null results are tightening the WIMP parameter space and nudging researchers toward axions or modified gravity, with next steps focusing on larger detectors, sharper axion experiments, and more detailed sky maps to push for a direct signal or stronger exclusions.

via Space Daily|

#axion #cosmology #dark-matter

space6 days ago•14 min saved

Cosmic Duo Tests Cosmology: Giant Arc and Big Ring in Close Proximity

Two gigantic structures—the Giant Arc and the Big Ring—share the same redshift (~9.2 billion light-years) and lie about 12 degrees apart in the sky, inferred from Mg II absorption in quasar spectra rather than direct imaging. If real and physically connected, they challenge the cosmological principle of large-scale homogeneity under Lambda-CDM and would require explanations for such vast, ordered patterns; however, statistics and potential artefacts are debated, and future surveys and simulations will test their persistence and implications for cosmology.

via Space Daily|

#big-ring #cosmological-principle #cosmology

space7 days ago•91 min saved

A decade-long sky movie: Rubin Observatory to map a dynamic universe

The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) has begun, capturing thousands of 30-second exposures every night for 10 years to create a digital color movie of the southern sky, with real-time alerts on unusual changes and public data access. The project aims to illuminate dark matter and dark energy, map stellar histories and asteroids, and possibly uncover unexpected phenomena that could revolutionize astronomy, while facing challenges from ultra-bright satellites and other technical hurdles.

via Live Science|

#cosmology #dark-energy #dark-matter

space8 days ago•12 min saved

Ancient galaxy defies early-growth limits, seen 290 million years after the Big Bang

JWST confirmed the galaxy JADES-GS-z14-0 at about z~14.3 (roughly 290 million years after the Big Bang), unusually large and bright for its age, and ALMA detected oxygen indicating heavy-element enrichment far earlier than models predicted—raising questions about how quickly the first galaxies assembled while not overturning the Big Bang framework.

via Space Daily|

#cosmology #early-universe #galaxies

science8 days ago•14 min saved

JWST’s Early Universe Puzzles Fuel Fresh Theories

JWST observations of the infant universe reveal unexpectedly large black holes and bright, diverse galaxies, prompting competing theories from large seed black holes and super-Eddington growth to direct-collapse scenarios and naked black holes; researchers are refining models with new simulations and MIRI data, as they work to determine which explanations best fit the early cosmos and the process of reionization.

via Quanta Magazine|

#black-holes #cosmology #early-galaxies

science10 days ago•11 min saved

DESI data hint the cosmos isn't uniform at the largest scales

New DESI-based analysis finds directional patterns in the galaxy distribution that persist across billions of light-years, suggesting the universe may not be perfectly uniform on the largest scales. If confirmed, this challenges the cosmological principle and could force revisions to the standard Lambda-CDM model, including possibilities of more complex dark-matter interactions or larger-scale inhomogeneities. The observed patterns are stronger than those produced by simulations, underscoring the need for further data from DESI, Euclid and other surveys to verify the result and guide new theories of cosmic structure.

via The Conversation|

#cosmological-principle #cosmology #dark-matter

science10 days ago•24 min saved

Cosmic census begins as Rubin Observatory launches decade-long sky survey

The Vera C. Rubin Observatory in Chile has officially begun its 10-year survey to image the southern sky, taking hundreds of images per night to build a deep census of billions of stars and galaxies and to probe dark matter and dark energy, with researchers hoping to shed light on how galaxies form and cluster over cosmic time.

via New York Post|

#astronomy #cosmology #dark-energy

space10 days ago•10 min saved

Massive Cosmic Filament Reveals Synchronized Galaxy Spins, Posing New Spin-Formation Questions

Astronomers identified a colossal cosmic filament about 50 million light-years long containing roughly 300 galaxies, many of which appear to rotate in sync with the filament at about 110 km/s. This coordinated motion challenges standard ideas of how galaxies acquire spin (tidal torque) and suggests large-scale structure may influence spins more than expected. It’s an early, single striking case that requires more surveys and simulations to determine whether this synchrony is common and how theory might adapt.

via Space Daily|

#astronomy #cosmicweb #cosmology

science10 days ago•116 min saved

Rubin Observatory kicks off a decade-long cosmic census

The Vera C. Rubin Observatory, home to the world’s largest digital camera, has begun a 10‑year survey of the universe, creating a comprehensive sky map to study galaxies, asteroids, dark matter, and the evolution of the cosmos.

via AP News|

#astronomy #cosmology #science

science11 days ago•50 min saved

Cosmic Ring of Galaxies Defies Current Cosmology

Astronomers have identified a colossal, near-perfect ring of galaxies called The Big Ring, about 1.3 billion light-years across, plus the nearby Giant Arc in the same sky region. These structures exceed expected sizes and don’t fit standard formation scenarios, raising questions about the Cosmological Principle and potentially hinting at new physics (e.g., conformal cyclic cosmology or cosmic strings). The findings, led by Alexia Lopez of the University of Central Lancashire and published in the Journal of Cosmology and Astroparticle Physics, warrant more observations to determine their significance and frequency across the universe.

via Yahoo|

#alexia-lopez #cosmological-principle #cosmology

space11 days ago•5 min saved

Star Collapse May Forge a Mini-Universe: Gravastars as Black Hole Alternatives

A new study proposes gravastars—ultra-compact objects formed when collapsing stars create a miniature universe inside, with dark-energy interiors that halt collapse and mimic black holes without horizons or singularities—offering a GR-consistent alternative to black holes. Yet the mechanism requires fine-tuning, questions of stability remain, and it’s unclear how such objects could be distinguished observationally; formation remains a key open problem.

via Universe Today|

#black-holes #but-we-only-need-five-ensure-only-five-so-remove-extra #cosmology

science11 days ago•5 min saved

Gigantic Ring of Galaxies Stuns Cosmologists

Astronomers led by Alexia Lopez report two ultra-large galaxy structures—the 1.3-billion-light-year Big Ring and the nearby Giant Arc—challenging standard cosmology and the Cosmological Principle; they are not BAOs, and could hint at exotic explanations like conformal cyclic cosmology or cosmic strings; light from these structures has traveled about 6.9 billion years, and more such discoveries are needed to understand their origin.

via ScienceAlert|

#big-ring #cosmology #galaxies