Discovery, Characterization, and Potential Origins of a Stream in the Stellar Halo of Nearby LMC-Mass Galaxy NGC 55
Year: 2026
Type: preprint
Abstract: We present a previously undetected stellar stream in the halo of the LMC-mass dwarf galaxy NGC 55 (2 Mpc), as part of an ongoing effort to characterize the stellar halos of LMC/SMC-mass dwarfs in the DEEP component of the DECam Local Volume Exploration (DELVE) survey. This structure is aligned with an outflow traced by H$α$ emission, a spur and cloud of neutral hydrogen, and the ultra-diffuse and possibly disrupting satellite galaxy NGC 55-dw1. We investigate possible ex-situ progenitor scenarios for this stream through the local luminosity-metallicity relation and a set of toy dynamical models that include gaseous, stellar, and dark matter components. If the stream is a product of a previous merger, the progenitor galaxy had an absolute magnitude $M_V \leq -7.2$ and a stellar mass $M_* \geq 10^5 M_{\odot}$ based on extrapolations of the detected stellar populations. If it is disrupted material from the ultra-diffuse satellite, their shared progenitor had an absolute magnitude $M_V \leq -8.3$ and a stellar mass $M_* \geq 10^{5.2} M_{\odot}$. We compare our stream and progenitor scenarios to those for NGC 300, a galaxy with a stellar mass similar to that of NGC~55 and known to host multiple structures in its halo. Our results demonstrate that even relatively isolated LMC-mass galaxies can have complex accretion histories, providing new tests of hierarchical galaxy formation at low masses.
Source: arXiv (Cornell University)
Authors: Velguth, Benjamin N., Mutlu-Pakdil, Burçin, Tollerud, Erik, Pearson, Sarah, Spekkens, Kristine, Doliva-Dolinsky, Amandine, Jones, Michael G., Crnojević, Denija, Carlin, Jeffrey L., Sand, David J., Bennet, Paul, Stringfellow, Guy, Cerny, William, Drlica-Wagner, Alex, Sakowska, Joanna D., Jensen, Jaclyn, Hunter, Laura C., Bell, Eric F., Martínez-Delgado, David, Chiti, Anirudh, Smercina, Adam, Kallivayalil, Nitya, Prabhu, Deepthi S., Riley, Alexander H., Choi, Yumi, Noël, Noelia E. D., Campana, Sasha N., Herron, Guinevere, Walker, Alistair R., Pace, Andrew B., Martínez-Vázquez, Clara E., Bom, Clecio R., Carballo-Bello, Julio A., Massana, Pol, Medina, Gustavo E.
Institutions: Dartmouth College, Space Telescope Science Institute, University of Copenhagen, Technical University of Denmark, Queen's University, Institut für Palliative Care, Infrared Processing and Analysis Center, University of Tampa, University of Colorado Boulder, Yale University, Instituto de Astrofísica de Andalucía, Kavli Institute for Particle Astrophysics and Cosmology, University of Arizona, NSF NOIRLab, University of Surrey, Cerro Tololo Inter-American Observatory, University of Virginia, University of Toronto, University of Tarapacá, Centro Brasileiro de Pesquisas Físicas, California Institute of Technology, Stanford University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Research Corporation for Science Advancement, University of California, Santa Cruz, University of Pennsylvania, Ohio State University, University of Portsmouth, National Centre for Supercomputing Applications, University College London, European Commission, University of Sussex, Deutsche Forschungsgemeinschaft, Eidgenössische Technische Hochschule Zürich, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Financiadora de Estudos e Projetos, Institut de Física d'Altes Energies, University of Illinois at Urbana-Champaign, Center for Cosmology and Astroparticle Physics, Ohio State University, Kavli Institute for Cosmological Physics, University of Chicago, Science and Technology Facilities Council, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Division of Astronomical Sciences, Laboratory Directed Research and Development, Integrated Electronics Engineering Center, Binghamton University, Argonne National Laboratory, Fermilab, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory
Awards: G1275459280, Collaborative Research: Cosmic Shear on Extremely Large Scales with the Dark Energy Camera, G1818210073, Collaborative Research: Jump Starting LSST Proper Motion Science with 12 Years of DECam Observations, Collaborative Research: Cosmic Shear on Extremely Large Scales with the Dark Energy Camera, G2037078528, G2394197028, G3169836530, Understanding the diversity of low mass galaxies, G6456579225, Studying the Threshold of Galaxy Formation with Ultra-Faint Galaxies
OpenAlex ID: W7213888673