The volume density of giant low surface brightness galaxies
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Date
2023
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Abstract
Rare giant low surface brightness galaxies (gLSBGs) act as a stress test for the current galaxy formation paradigm. To answer the question 'How rare are they?', we estimate their volume density in the local Universe. A visual inspection of 120 deg(2) covered by deep Subaru Hyper Suprime-Cam data was performed independently by four team members. We detected 42 giant disky systems (30 of them isolated) at z <= 0.1 with either g-band 27.7 mag arcsec(-2) isophotal radius or four disc scale lengths 4h >= 50 kpc, 37 of which (including 25 isolated) had low central surface brightness (mu(0,g) >= 22.7 mag arcsec(-2)). This corresponds to volume densities of 4.70 x 10(-5) Mpc(-3) for all galaxies with giant extended discs and 4.04 x 10(-5) Mpc(-3) for gLSBGs, which converts to similar to 12700 such galaxies in the entire sky out to z < 0.1. These estimates agree well with the result of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) cosmological hydrodynamical simulation. Giant disky galaxies represent the large-sized end of the volume density distribution of normal-sized spirals, suggesting the non-exceptional nature of giant discs. We observe a high active galactic nucleus fraction among the newly found gLSBGs.
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galaxies: evolution, galaxies: formation, galaxies: kinematics and dynamics, galaxies: spiral, galaxies: photometry