Kavli Affiliate: Chihway Chang
| First 5 Authors: Chun-Hao To, Chun-Hao To, , ,
| Summary:
We present the first detection of weak gravitational lensing around
spectroscopically confirmed dwarf galaxies, using the large overlap between
DESI DR1 spectroscopic data and DECADE/DES weak lensing catalogs. A clean dwarf
galaxy sample with well-defined redshift and stellar mass cuts enables excess
surface mass density measurements in two stellar mass bins ($log
rmM_*=[8.2, 9.2]~M_odot$ and $log rmM_*=[9.2, 10.2]~M_odot$), with
signal-to-noise ratios of $5.6$ and $12.4$ respectively. This signal-to-noise
drops to $4.5$ and $9.2$ respectively for measurements without applying
individual inverse probability (IIP) weights, which mitigates fiber
incompleteness from DESI’s targeting. The measurements are robust against
variations in stellar mass estimates, photometric shredding, and lensing
calibration systematics. Using a simulation-based modeling framework with
stellar mass function priors, we constrain the stellar mass-halo mass relation
and find a satellite fraction of $simeq 0.3$, which is higher than previous
photometric studies but $1.5sigma$ lower than $Lambda$CDM predictions. We
find that IIP weights have a significant impact on lensing measurements and can
change the inferred $f_rmsat$ by a factor of two, highlighting the need
for accurate fiber incompleteness corrections for dwarf galaxy samples. Our
results open a new observational window into the galaxy-halo connection at low
masses, showing that future massively multiplexed spectroscopic observations
and weak lensing data will enable stringent tests of galaxy formation models
and $Lambda$CDM predictions.
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