IllustrisTNG Simulation Reveals How Low Surface Brightness Galaxies Develop Their Diffuse Structure
A new study using the IllustrisTNG cosmological simulation analyzed roughly 12,000 low surface brightness galaxies (LSBGs) to determine why they are so diffuse and faint. The research found that elevated angular momentum and halo spin parameters redistribute stellar mass outward from galactic centers, lowering central surface brightness, rather than differences in star formation rates. The findings help clarify a long-standing question about what physically distinguishes LSBGs from their brighter counterparts.
Researchers used the IllustrisTNG simulation suite to study the formation and evolution of approximately 12,000 low surface brightness galaxies (LSBGs) spanning a wide stellar mass range of 10⁹ to 10¹² solar masses. By tracing merger trees, they tracked how properties such as stellar surface density, specific angular momentum, and halo spin parameter evolved over time. The central finding is that the diffuse nature of LSBGs is primarily driven by increases in angular momentum and inner halo spin, which push star formation and stellar mass toward galactic outskirts rather than concentrating it in the center. Notably, the star formation histories of LSBGs are broadly similar to those of high surface brightness galaxies (HSBGs), with the key difference lying in the spatial distribution of new stars rather than the timing or total amount of star formation. Once a galaxy establishes its low surface brightness character, it tends to remain stable, experiencing few strong changes in central surface density or morphology. The study, accepted for publication in Monthly Notices of the Royal Astronomical Society, offers a coherent simulation-based framework for understanding LSBG emergence across a broad mass range.
What's missing
The study relies entirely on the IllustrisTNG simulation, so it is subject to the limitations of that model's subgrid physics prescriptions (e.g., stellar feedback, AGN feedback), which may not fully capture real galaxy formation processes. The paper does not directly compare simulation predictions against observed LSBG populations to validate the angular momentum mechanism observationally.
What different sources said
- arXiv astro-phCenter
The emergence of the faint nature of Low Surface Brightness Galaxies in the IllustrisTNG simulation
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.