Tripling the Census of Dwarf AGN Candidates Using DESI Early Data

Pucha, Ragadeepika; Juneau, S.; Dey, Arjun; Siudek, M.; Mezcua, M.; Moustakas, J.; BenZvi, S.; Hainline, K.; Hviding, R.; Mao, Yao-Yuan; Alexander, D. M.; Alfarsy, R.; Circosta, C.; Guo, Wei-Jian; Manwadkar, V.; Martini, P.; Weaver, B. A.; Aguilar, J.; Ahlen, S.; Bianchi, D.; Brooks, D.; Canning, R.; Claybaugh, T.; Dawson, K.; de la Macorra, A.; Dey, Biprateep; Doel, P.; Font-Ribera, A.; Forero-Romero, J. E.; Gaztañaga, E.; Gontcho A Gontcho, S.; Gutierrez, G.; Honscheid, K.; Kehoe, R.; Koposov, S. E.; Lambert, A.; Landriau, M.; Le Guillou, L.; Meisner, A.; Miquel, R.; Prada, F.; Rossi, G.; Sanchez, E.; Schlegel, D.; Schubnell, M.; Seo, H.; Sprayberry, D.; Tarlé, G.; Zou, H.
Bibliographical reference

The Astrophysical Journal

Advertised on:
3
2025
Number of authors
49
IAC number of authors
1
Citations
0
Refereed citations
0
Description
Using early data from the Dark Energy Spectroscopic Instrument (DESI) survey, we search for active galactic nuclei (AGN) signatures in 410,757 line-emitting galaxies. By employing the BPT emission-line ratio diagnostic diagram, we identify AGNs in 75,928/296,261 (≈25.6%) high-mass ( 9.5) and 2444/114,496 (≈2.1%) dwarf ( 9.5) galaxies. Of these AGN candidates, 4181 sources exhibit a broad Hα component, allowing us to estimate their BH masses via virial techniques. This study more than triples the census of dwarf AGNs and doubles the number of intermediate-mass black hole (MBH ≤ 106M⊙) candidates, spanning a broad discovery space in stellar mass (7 12) and redshift (0.001 <z < 0.45). The observed AGN fraction in dwarf galaxies (≈2.1%) is nearly four times higher than prior estimates, primarily due to DESI's smaller fiber size, which enables the detection of lower-luminosity dwarf AGN candidates. We also extend the MBH–M⋆ scaling relation down to 8.5 and 4.4, with our results aligning well with previous low-redshift studies. The large statistical sample of dwarf AGN candidates from current and future DESI releases will be invaluable for enhancing our understanding of galaxy evolution at the low-mass end of the galaxy mass function.