AtLAST -- Cosmology with submillimetre galaxies magnification bias

TL;DR

Magnification bias from submillimetre galaxies provides a promising, independent method for probing cosmology, especially with future wide-field surveys like AtLAST that can overcome current limitations.

Contribution

This paper highlights the potential of magnification bias as a powerful cosmological probe and advocates for the use of next-generation facilities like AtLAST to unlock its full potential.

Findings

Magnification bias probes galaxy-matter correlations without relying on galaxy shapes.

Next-generation surveys can significantly improve the precision of magnification bias measurements.

Magnification bias offers complementary constraints to shear, BAO, and CMB data.

Abstract

Magnification bias offers a uniquely powerful and independent route to cosmological information. As a gravitational-lensing observable, it probes galaxy-matter correlations without relying on galaxy shapes, PSF modelling, or intrinsic-alignment corrections. Its sensitivity spans both geometry and growth: magnification bias simultaneously responds to the matter density, the amplitude of structure, and the redshift evolution of dark energy (DE) below $z \leq 1$. Importantly, its parameter degeneracy directions differ from those of shear, Baryon Acoustic Oscillations (BAO), and Cosmic Microwave Background (CMB) data, making it a complementary and consistency-check probe with substantial diagnostic value for the next decade of precision cosmology. However, the current potential of magnification bias is restricted by limited sky coverage, catalogue inhomogeneities, and insufficiently precise redshift or number-count characterisation. A next-generation wide-field submillimetre facility like AtLAST -- capable of uniform, deep surveys and spectroscopic mapping -- would overcome these limitations and transform magnification bias into a competitive, high-precision cosmological tool.