The Mystery of Cosmic Dust: Weighing a Galaxy express
Based on new NIRSpec/IFU spectroscopic data for galaxy S1 (z=3.2439±0.0002, previously z>5) and photometry of three objects (S1, S2, S3), stellar mass estimates were revised using the Prospector code. The influence of prior assumptions about the shape of the star formation history (constant or rising baseline for a non-parametric approach), the dust attenuation law, and the inclusion of emission lines was analyzed. A pronounced degeneracy between the dust absorption curve slope, its overall amount, and stellar mass was found. The revised masses are log(M*/M⊙)≈10.36, 10.95, and 10.31; using a rising history leads to systematically lower values. The results demonstrate systematic uncertainties in SED modeling for dusty sources, yet two galaxies retain their status as some of the most massive and efficiently star-forming systems at their z.
Astronomers pointed the James Webb at three galaxies whose light traveled 12 billion years. Early data pointed to incredibly fast growth — like an infant reaching adult height in just a year, clashing with the expansion of the Universe.
Fresh analysis of light (spectroscopy) revealed that one of the galaxies is closer, and recalculations accounting for cosmic dust (microscopic particles that hinder observations) yielded new numbers. The mass estimate depends on how much dust dims the light — as if you were weighing a statue behind glass of varying fog levels. The slightest change in opacity shifts the result. After correction, all three giants 'shed weight'; in one case, the mass was halved. Still, two remain too massive for their age, defying cosmology.
🎯 Cosmic dust grains are solid microparticles (mostly carbon and silicates) the size of a virus, born in the shells of old stars; together they create a translucent veil capable of masking whole armies of luminaries.