The Gemini North telescope reveals a relic of the first galaxies.
A unique extremely faint dwarf galaxy has been discovered in the outer fringes of the Andromeda Galaxy thanks to the keen eyes of an amateur astronomer examining archival data processed by the NSF NOIRLab Community Science and Data Center. The dwarf galaxy – Pegasus V – was revealed to contain very few heavier elements and is likely to be a fossil of the first galaxies in follow-up observations by professional astronomers using the Gemini International Observatory, a Program of NSF’s NOIRLab. An unusual extremely faint dwarf galaxy was discovered at the edge of the Andromeda Galaxy with the help of several facilities at NSF’s NOIRLab. The galaxy, called Pegasus V, was first spotted as part of a systematic search for Andromeda dwarfs coordinated by David Martinez-Delgado of the Instituto de Astrofísica de Andalucía, Spain, when amateur astronomer Giuseppe Donatiello discovered a strange ‘smudge » DESI in data. Image of legacy imaging surveys.[1] The image was taken with the US Department of Energy’s Dark Energy Camera on the Víctor M. Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). Data were processed through the community pipeline operated by NOIRLab’s Community Data and Science Center (CSDC). Faint stars in Pegasus V were revealed in deeper observations by astronomers using the larger Gemini North 8.1-meter telescope with the GMOS instrument, confirming that it is an extremely faint dwarf galaxy on the outskirts of the Andromeda Galaxy. Gemini North in Hawaii is one half of the International Gemini Observatory. Observations of Gemini have shown that the galaxy appears to be extremely deficient in heavier elements compared to similar dwarf galaxies, meaning it is very old and likely a fossil of the first galaxies in the Universe. “We found an extremely faint galaxy whose stars formed very early in the history of the Universe,” commented Michelle Collins, an astronomer at the University of Surrey, UK and lead author of the paper announcing this discovery. “This discovery marks the first time that a galaxy this faint has been found around the Andromeda Galaxy using an astronomical survey that was not specifically designed for this task.” A unique extremely faint dwarf galaxy has been discovered in the outer fringes of the Andromeda Galaxy thanks to the sharp eyes of an amateur astronomer examining archival data from the US Department of Energy’s Dark Energy Camera on the Víctor M. Blanco 4-meter Telescope at the Inter-American Observatory Cerro Tololo (CTIO) and processed by the Community Science and Data Center (CSDC). Monitoring by professional astronomers using the International Gemini Observatory has revealed that the dwarf galaxy — Pegasus V — contains very few heavier elements and is likely a fossil of the first galaxies. All three facilities involved are NSF NOIRLab Programs. Credit: International Gemini Observatory/NOIRLab/NSF/AURA Credits: Image processing: TA Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) & D. de Martin (NSF’s NOIRLab) The faintest galaxies are considered fossils of the first galaxies to form, and these galactic remnants contain clues to the formation of the first stars. While astronomers expect the Universe to be teeming with faint galaxies like Pegasus V,[2] they have not yet discovered nearly as much as their theories predict. If there really are fewer faint galaxies than predicted, this would spell serious trouble for astronomers’ understanding of cosmology and dark matter. Discovering examples of these faint galaxies is therefore an important endeavor, but also a difficult one. Part of the challenge is that these faint galaxies are extremely difficult to detect, appearing as just a few faint stars hidden in vast images of the sky. “The problem with these extremely faint galaxies is that they have very few of the bright stars that we normally use to identify them and measure their distances,” explained Emily Charles, a PhD student at the University of Surrey who was also involved in the study. . “Gemini’s 8.1-meter mirror allowed us to find faint, old stars that allowed us to measure the distance to Pegasus V and determine that its stellar population is extremely large.” The strong concentration of old stars the team found in Pegasus V suggests that the object is likely a fossil of the first galaxies. Compared to the other faint galaxies around Andromeda, Pegasus V appears uniquely old and metal-poor, indicating that its star formation stopped very early indeed. “We hope that further study of the chemical properties of Pegasus V will provide clues to the earliest star formation periods in the Universe,” Collins concluded. “This tiny fossil galaxy from the early Universe may help us understand how galaxies form and whether our understanding of dark matter is correct.” “The public-access Gemini North telescope provides a number of opportunities for community astronomers,” said Martin Steele, Gemini program manager at the National Science Foundation. “In this case, Gemini supported this international team to confirm the presence of the dwarf galaxy, physically correlate it with the Andromeda Galaxy, and determine the metal-deficient nature of its evolved stellar population.” Upcoming astronomical facilities are set to shed more light on faint galaxies. Pegasus V witnessed an era in the history of the Universe known as reionization, and other objects dating from this era will soon be observed with NASA’s James Webb Space Telescope. Astronomers also hope to discover other such faint galaxies in the future using the Vera C. Rubin Observatory, a Program of NSF’s NOIRLab. The Rubin Observatory will conduct an unprecedented, decade-long survey of the visual sky called the Legacy Survey of Space and Time (LSST). Notes More information This research was presented in a paper titled “Pegasus V — a newly discovered extremely faint dwarf galaxy on the outskirts of Andromeda” to appear in the Monthly Notices of the Royal Astronomical Society. Reference: “Pegasus V — a newly discovered extremely faint dwarf galaxy on the outskirts of Andromeda” by Michelle LM Collins, Emily JE Charles, David Martínez-Delgado, Matteo Monelli, Noushin Karim, Giuseppe Donatiello, Erik J. Boll. , Accepted, Monthly Notices of the Royal Astronomical Society.arXiv:2204.09068 The team consists of Michelle LM Collins (Department of Physics, University of Surrey, UK), Emily JE Charles (Department of Physics, University of Surrey, UK), David Martinez-Delgado (Institute of Astrophysics of Andalusia, Spain), Matteo Monelli (Canary Institute of Astrophysics (IAC) and University of La Laguna, Spain), Noushin Karim (Department of Physics, University of Surrey, UK), Giuseppe Donatiello (UAI – Unione Astrofili Italiani, Italy), Erik J. Tollerud (Space Telescope Science Institute, USA), Walter Boschin (Institute of Astrophysics of the Canary Islands (IAC), University of La Laguna and G. Galilei Foundation – INAF (Nazionale Galileo Telescope), Spain).
