Study Suggests Universe May Be Decelerating Based on Corrected Supernova Data
A new analysis of Type Ia supernovae from the Pantheon+ catalogue, adjusted for progenitor age effects, indicates the universe's expansion may be decelerating rather than accelerating. The research applies corrections for how stellar age affects supernova brightness to measure the deceleration parameter. This challenges the widely accepted model of cosmic acceleration driven by dark energy, though the finding requires independent verification.
Researchers examined how accounting for progenitor age-dependent luminosity evolution in Type Ia supernovae affects measurements of cosmic deceleration. Using the Pantheon+ supernova catalogue with redshift-dependent corrections, they found that the monopole component of the deceleration parameter shifts to positive values, suggesting deceleration. The analysis also confirms previous findings of a strong local dipole anisotropy aligned with the bulk flow, with only a small monopole component at distances exceeding a few hundred megaparsecs. The study applies systematic corrections to standard candles used in cosmology to measure the universe's expansion history. These findings, if confirmed, would represent a significant departure from the current cosmological consensus based on observations of distant supernovae.
What's missing
The study's own limitations and caveats are not detailed in the abstract provided. Key open questions include: whether the progenitor age corrections are fully validated across the entire supernova sample, how sensitive the results are to the specific correction methodology, and whether independent datasets (such as other supernova compilations or complementary cosmological probes like cosmic microwave background or baryon acoustic oscillations) support these findings.
What different sources said
- arXiv astro-phCenter
Pantheon+ supernovae corrected for progenitor age indicate the universe is decelerating
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.