Extragalactic stellar tidal streams: Observations meet simulation

¹ Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Plaza de las Ciencias 2, E-28040 Madrid, Spain
² Leiden Observatory, Leiden University, P.O. Box 9513 2300 RA Leiden, The Netherlands
³ Instituto de Física de Partículas y del Cosmos (IPARCOS), Fac. CC. Físicas, Universidad Complutense de Madrid, Plaza de las Ciencias, 1, E-28040 Madrid, Spain
⁴ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Unidad Asociada al CSIC, Plaza San Juan 1, 44001 Teruel, Spain
⁵ ARAID Foundation, Avda. de Ranillas, 1-D, E-50018 Zaragoza, Spain
⁶ Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía, E-18080 Granada, Spain
⁷ Institute of Astronomy and Department of Physics, National Tsing Hua University, Kuang Fu Rd. Sec. 2, Hsinchu 30013, Taiwan
⁸ Center for Informatics and Computation in Astronomy, National Tsing Hua University, Kuang Fu Rd. Sec. 2, Hsinchu 30013, Taiwan
⁹ Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Box 43 SE-221 00 Lund, Sweden
¹⁰ Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
¹¹ Department of Physics, University of Surrey, Guildford GU2 7XH, UK
¹² Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Im Neuenheimer Feld 205, D-69120 Heidelberg, Germany
¹³ Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Straße 2, D-69120 Heidelberg, Germany
¹⁴ Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotnik ow 32/46, 02-668 Warsaw, Poland
¹⁵ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH13LE, United Kingdom
¹⁶ UAI – Unione Astrofili Italiani/P.I. Sezione Nazionale di Ricerca Profondo Cielo, 72024 Oria, Italy

^⋆ Corresponding author.

Received: 29 October 2024
Accepted: 16 June 2025

Abstract

Context. According to the well-established hierarchical framework for galaxy evolution, galaxies grow through mergers with other galaxies. The ΛCDM cosmological model predicts that the stellar halos of massive galaxies are rich in remnants resulting from minor mergers. Stellar Streams Legacy Survey (SSLS) has provided a first release of a catalogue with a statistically significant sample of stellar streams in the local Universe, detected in deep images from DESI Legacy Surveys and Dark Energy Survey (DES).

Aims. The main objective is to compare observations of stellar tidal streams from the SSLS catalogue with predictions from state-of-the-art cosmological simulations regarding their abundance, up to a redshift of z < 0.02, according to the ΛCDM model.

Methods. In particular, we used the outcome of cosmological simulations from Copernicus Complexio, TNG50 of the IllustrisTNG project, and Auriga to generate mock images of nearby halos and search for stellar streams. We compared the stream frequency and characteristics found in these images, as well as the results of a photometric analysis of the simulations data with DES observations.

Results. We found a generally good agreement between the real images and the simulated ones regarding frequency and photometry of streams, while we found differences in the stream morphology between the observations and the simulations, and among the simulations themselves. By varying the sky background of the synthetic images to emulate different surface brightness limit levels, we were also able to obtain predictions for the detection rate of stellar tidal streams up to a surface brightness limit of 35 mag arcsec⁻².

Conclusions. The cosmological simulations predict that with an instrument akin to the one used in DES, it would be necessary to attain a surface brightness limit of 32 mag arcsec⁻² in the r-band to achieve a frequency of up to ∼70% in the detection of stellar tidal streams around galaxies in the redshift range considered here.