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

Journal Article · Wed Sep 24 00:00:00 EDT 2025 · No journal information

OSTI ID:3018647

To, Chun-Hao ^[1]; Chang, Chihway ^[1]; Anbajagane, Dhayaa ^[1]; Wechsler, Risa H. ^[2]; Drlica-Wagner, Alex ^[3]; Adamów, M. ^[4]; Alarcon, A. ^[5]; Becker, M. R. ^[6]; Carballo-Bello, J. A. ^[7]; Cawthon, R. ^[8]; Chicoine, N. ^[9]; Doux, C. ^[10]; Esteves, J. H. ^[11]; Ferguson, P. S. ^[12]; Gatti, M. ^[13]; Gruen, D. ^[14]; Gruendl, R. A. ^[15]; Herron, K. ^[16]; James, David J. ^[17]; Martínez-Vázquez, C. E. ^[18] ; Mau, S. ^[19]; McCullough, J. ^[20]; Medina, G. E. ^[21]; Mutlu-Pakdil, B. ^[16]; Navarro-Alsina, A. ^[22]; Noël, N. E.D. ^[23]; Pace, A. B. ^[24]; Raveri, M. ^[25]; Riley, A. H. ^[26]; Sand, D. J. ^[27]; Secco, L. F. ^[13]; Shin, T. ^[28]; Stringfellow, G. S. ^[29]; Suson, D. ^[30]; Tan, C. Y. ^[31]; Teixeira, R. ^[32]; Zenteno, A. ^[33]; Zhang, Z. ^[34]

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1. Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; SkAI, Chicago
2. Stanford U.; KIPAC, Menlo Park; SLAC
3. Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; SkAI, Chicago; Fermilab
4. Illinois U., Urbana (main); Illinois U., Urbana, Astron. Dept.
5. ICE, Bellaterra
6. Argonne (main)
7. Tarapaca U.
8. Unlisted, US
9. Chicago U., Astron. Astrophys. Ctr.; Pittsburgh U.
10. LPSC, Grenoble
11. Harvard U.
12. Washington U., Seattle
13. Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP
14. LMU Munich (main)
15. Illinois U., Urbana, Astron. Dept.; Illinois U., Urbana (main)
16. Dartmouth Coll.
17. Unlisted, US, MA; Integrated Applied Physics, Waltham
18. Gemini Observ., Hilo
19. Stanford U.; KIPAC, Menlo Park
20. Princeton U., Astrophys. Sci. Dept.
21. Toronto U., Astron. Dept.
22. Campinas State U.
23. Surrey U.
24. Virginia U., Astron. Dept.
25. MIT, Cambridge, Dept. Phys.; INFN, Genoa
26. Durham U., ICC; Lund U.
27. Arizona U., Astron. Dept. - Steward Observ.
28. Carnegie Mellon U.
29. Colorado U.
30. Purdue U., Calumet
31. Chicago U.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP
32. Chicago U., Astron. Astrophys. Ctr.; Duke U.
33. Cerro-Tololo InterAmerican Obs.
34. Chicago U., Astron. Astrophys. Ctr.; Stanford U.; SLAC

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.

• Research Organization: INFN, Genoa; Durham U., ICC; Chicago U.; Lund U.; Chicago U., KICP; Arizona U., Astron. Dept. - Steward Observ.; Illinois U., Urbana, Astron. Dept.; Unlisted, US, MA; ICE, Bellaterra; Surrey U.; SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Illinois U., Urbana (main); Carnegie Mellon U.; Tarapaca U.; Pittsburgh U.; SkAI, Chicago; Chicago U., Astron. Astrophys. Ctr.; Duke U.; Argonne National Laboratory (ANL), Argonne, IL (United States); Cerro-Tololo InterAmerican Obs.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Harvard U.; Toronto U., Astron. Dept.; Integrated Applied Physics, Waltham; Purdue U., Calumet; Unlisted, US; Campinas State U.; Dartmouth Coll.; MIT, Cambridge, Dept. Phys.; Chicago U., EFI; Gemini Observ., Hilo; LPSC, Grenoble; LMU Munich (main); Virginia U., Astron. Dept.; Princeton U., Astrophys. Sci. Dept.; Colorado U.; Washington U., Seattle; Stanford U.
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: 89243024CSC000002
• OSTI ID: 3018647
• Report Number(s): FERMILAB-PUB-25-0738-PPD; oai:inspirehep.net:2973432; arXiv:2509.20458
• Journal Information: No journal information, Journal Name: No journal information
• Country of Publication: United States
• Language: English