A DECADE of dwarfs: first detection of weak lensing around spectroscopically confirmed low-mass galaxies

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Autori principali: To, Chun-Hao, Chang, Chihway, Anbajagane, Dhayaa, Wechsler, Risa H., Drlica-Wagner, Alex, Adamów, M., Alarcon, A., Becker, M. R., Carballo-Bello, J. A., Cawthon, R., Chicoine, N., Doux, C., Esteves, J. H., Ferguson, P. S., Gatti, M., Gruen, D., Gruendl, R. A., Herron, K., James, David J., Martínez-Vázquez, C. E., Mau, S., McCullough, J., Medina, G. E., Mutlu-Pakdil, B., Navarro-Alsina, A., Noël, N. E. D., Pace, A. B., Raveri, M., Riley, A. H., Sand, D. J., Secco, L. F., Shin, T., Stringfellow, G. S., Suson, D., Tan, C. Y., Teixeira, R., Zenteno, A., Zhang, Z.
Natura: Preprint
Pubblicazione: 2025
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author To, Chun-Hao
Chang, Chihway
Anbajagane, Dhayaa
Wechsler, Risa H.
Drlica-Wagner, Alex
Adamów, M.
Alarcon, A.
Becker, M. R.
Carballo-Bello, J. A.
Cawthon, R.
Chicoine, N.
Doux, C.
Esteves, J. H.
Ferguson, P. S.
Gatti, M.
Gruen, D.
Gruendl, R. A.
Herron, K.
James, David J.
Martínez-Vázquez, C. E.
Mau, S.
McCullough, J.
Medina, G. E.
Mutlu-Pakdil, B.
Navarro-Alsina, A.
Noël, N. E. D.
Pace, A. B.
Raveri, M.
Riley, A. H.
Sand, D. J.
Secco, L. F.
Shin, T.
Stringfellow, G. S.
Suson, D.
Tan, C. Y.
Teixeira, R.
Zenteno, A.
Zhang, Z.
author_facet To, Chun-Hao
Chang, Chihway
Anbajagane, Dhayaa
Wechsler, Risa H.
Drlica-Wagner, Alex
Adamów, M.
Alarcon, A.
Becker, M. R.
Carballo-Bello, J. A.
Cawthon, R.
Chicoine, N.
Doux, C.
Esteves, J. H.
Ferguson, P. S.
Gatti, M.
Gruen, D.
Gruendl, R. A.
Herron, K.
James, David J.
Martínez-Vázquez, C. E.
Mau, S.
McCullough, J.
Medina, G. E.
Mutlu-Pakdil, B.
Navarro-Alsina, A.
Noël, N. E. D.
Pace, A. B.
Raveri, M.
Riley, A. H.
Sand, D. J.
Secco, L. F.
Shin, T.
Stringfellow, G. S.
Suson, D.
Tan, C. Y.
Teixeira, R.
Zenteno, A.
Zhang, Z.
contents 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 ($\log \rm{M}_*=[8.2, 9.2]~M_\odot$ and $\log \rm{M}_*=[9.2, 10.2]~M_\odot$), 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 $1.5σ$ lower than $Λ$CDM predictions. We find that IIP weights have a significant impact on lensing measurements and can change the inferred $f_{\rm{sat}}$ 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 $Λ$CDM predictions.
format Preprint
id arxiv_https___arxiv_org_abs_2509_20458
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A DECADE of dwarfs: first detection of weak lensing around spectroscopically confirmed low-mass galaxies
To, Chun-Hao
Chang, Chihway
Anbajagane, Dhayaa
Wechsler, Risa H.
Drlica-Wagner, Alex
Adamów, M.
Alarcon, A.
Becker, M. R.
Carballo-Bello, J. A.
Cawthon, R.
Chicoine, N.
Doux, C.
Esteves, J. H.
Ferguson, P. S.
Gatti, M.
Gruen, D.
Gruendl, R. A.
Herron, K.
James, David J.
Martínez-Vázquez, C. E.
Mau, S.
McCullough, J.
Medina, G. E.
Mutlu-Pakdil, B.
Navarro-Alsina, A.
Noël, N. E. D.
Pace, A. B.
Raveri, M.
Riley, A. H.
Sand, D. J.
Secco, L. F.
Shin, T.
Stringfellow, G. S.
Suson, D.
Tan, C. Y.
Teixeira, R.
Zenteno, A.
Zhang, Z.
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
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 ($\log \rm{M}_*=[8.2, 9.2]~M_\odot$ and $\log \rm{M}_*=[9.2, 10.2]~M_\odot$), 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 $1.5σ$ lower than $Λ$CDM predictions. We find that IIP weights have a significant impact on lensing measurements and can change the inferred $f_{\rm{sat}}$ 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 $Λ$CDM predictions.
title A DECADE of dwarfs: first detection of weak lensing around spectroscopically confirmed low-mass galaxies
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2509.20458