An unusual galaxy discovered on the edge of Andromeda – may reveal the history of the Universe

With the help of several facilities from NSF’s NOIRLab, an unusual ultra-faint dwarf galaxy has been discovered at the edge of the Andromeda Galaxy. The galaxy, called Pegasus V, was first discovered when amateur astronomer Giuseppe Donatiello spotted an interesting “spot” in the data as part of a systematic search for Andromeda dwarfs coordinated by David Martinez-Delgado of Spain’s Instituto Astrofísica de Andalucía.[{” attribute=””>DESI Legacy Imaging Surveys şəkli.^{” width=”777″ height=”396″ data-ezsrcset=”https://scitechdaily.com/images/Ultra-Faint-Dwarf-Galaxy-Pegasus-V-Circled-777×396.jpg 777w,https://scitechdaily.com/images/Ultra-Faint-Dwarf-Galaxy-Pegasus-V-Circled-400×204.jpg 400w,https://scitechdaily.com/images/Ultra-Faint-Dwarf-Galaxy-Pegasus-V-Circled-768×391.jpg 768w,https://scitechdaily.com/images/Ultra-Faint-Dwarf-Galaxy-Pegasus-V-Circled-1536×783.jpg 1536w,https://scitechdaily.com/images/Ultra-Faint-Dwarf-Galaxy-Pegasus-V-Circled.jpg 1992w” sizes=”(max-width: 777px) 100vw, 777px” ezimgfmt=”rs rscb1 src ng ngcb1 srcset” data-ezsrc=”https://scitechdaily.com/images/Ultra-Faint-Dwarf-Galaxy-Pegasus-V-Circled-777×396.jpg”/>}

Şəkil ABŞ Enerji Departamentinin Qaranlıq Enerji Kamerası ilə Cerro Tololo Amerikalararası Rəsədxanasında (CTIO) Víctor M. Blanco 4 metrlik teleskopunda çəkilib. Məlumatlar NOIRLab-ın İcma Elm və Məlumat Mərkəzi (CSDC) tərəfindən idarə olunan İcma Boru Kəməri vasitəsilə işlənmişdir.

The faint stars in Pegasus V were discovered by astronomers during deeper observations with the GMOS instrument using the larger, 8.1-meter Gemini North telescope, confirming that it is an ultra-faint dwarf galaxy on the edge of the Andromeda Galaxy. Gemini in Hawaii is one half of the International Gemini North Observatory.

Observations of Gemini have shown that the galaxy appears to be extremely deficient in heavy elements compared to similar dwarf galaxies, meaning it is very old and may be 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,” said Michel Collins, an astronomer at the University of Surrey in the UK and lead author of the paper announcing the discovery. “This discovery marks the first time that this faint galaxy has been found around the Andromeda Galaxy using an astronomical survey not specifically designed for this task.”

A unique ultra-faint dwarf galaxy has been discovered at the outer edges of the Andromeda Galaxy thanks to the keen eyes of an amateur astronomer poring over archival data at the US Department of Energy’s Víctor M. Blanco 4-meter Dark Energy Camera. It was developed by the telescope at the Cerro Tololo Inter-American Observatory (CTIO) and the Community Science and Data Center (CSDC). Follow-up by professional astronomers using the International Gemini Observatory revealed that the dwarf galaxy, Pegasus V, contains very few heavy elements and is likely a fossil of the first galaxies. All three participating facilities are NSF’s NOIRLab programs. Credit: International Gemini Observatory/NOIRLab/NSF/AURA Credit: Image processing: TA Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab), and D. de Martin (NSF’s NOIRLab)

The faintest galaxies are considered fossils of the first galaxies to form, and these galactic remnants contain clues about the formation of the earliest stars. Although astronomers expect the Universe to be full of faint galaxies like Pegasus V,^[2] they have not yet discovered as much as their theory predicts. If there really are far fewer faint galaxies than predicted, this poses a serious challenge to astronomers’ understanding of cosmology and cosmology. dark matter.

The discovery of samples of these faint galaxies is therefore an important but also a challenging task. Part of the difficulty is that these faint galaxies are notoriously difficult to detect and appear as a few sparse stars hidden in vast images of the sky.

“The problem with these extremely faint galaxies is that they contain very few of the bright stars that we normally use to identify them and measure their distances,” said Emily Charles, Ph.D., from the University of Surrey, who was involved in the study. . “Gemini’s 8.1-meter mirror allowed us to find faint, old stars, which allowed us to both measure the distance to Pegasus V and determine that its stellar population is extremely old.”

The strong concentration of old stars the team found in Pegasus V suggests the object may be the fossils of the first galaxies. Compared to other faint galaxies around Andromeda, Pegasus V appears uniquely old and metal-poor, suggesting that its star formation stopped very early indeed.

“We hope that future studies of the chemical properties of Pegasus V will provide clues about the earliest times of star formation in the Universe,” Collins concluded. “This tiny fossil galaxy of the early Universe can help us understand how galaxies form and whether our understanding of dark matter is correct.”

“For public access, the Gemini North telescope provides a number of opportunities for community astronomers,” said Martin Still, Gemini Program Officer at the National Science Foundation. “In this case, Gemini supported this international team to confirm the existence of a dwarf galaxy, physically link it to the Andromeda Galaxy, and determine the metal deficiency of its advanced stellar population.”

Upcoming astronomical instruments are poised to shed more light on faint galaxies. Pegasus V witnessed a period in the history of the Universe known as reionization, and other objects from this period will soon be observed. NASA’s James Webb Space Telescope. Astronomers also hope to discover such faint galaxies in the future using NSF’s NOIRLab program, the Vera C. Rubin Observatory. Rubin Observatory will conduct an unprecedented ten-year survey of the optical sky called the Legacy Survey of Space and Time (LSST).

Notes

1. DESI Legacy Imaging Surveys were conducted to identify targets for Dark Energy Spectroscopic Instrument (DESI) operations. These surveys are a unique blend of three projects that observe one-third of the night sky: the Dark Energy Camera Legacy Survey (DECaLS), observed by the DOE-built Dark Energy Camera (DECam) on the 4-meter Víctor M. Blanco; telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile; the Mayall z-band Legacy Survey (MzLS) with the Mosaic3 camera on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (KPNO); and the Beijing-Arizona Sky Survey (BASS) with the 90Prime camera on the 2.3-meter Bock Telescope, owned and operated by the University of Arizona and located at KPNO. CTIO and KPNO are programs of NSF’s NOIRLab.
2. Pegasus V is so named because it is the fifth dwarf galaxy in the constellation Pegasus. The distance on the sky between Pegasus V and the Andromeda Galaxy is about 18.5 degrees.

more info

The research is presented in the paper Pegasus V – A newly discovered ultra-faint dwarf galaxy on the edge of Andromeda. Monthly Notices of the Royal Astronomical Society.

Reference: Michelle LM Collins, Emily JE Charles, David Martínez-Delgado, Matteo Monelli, Noushin Karim, Giuseppe Donatiello, Eric J. Boschlerud, and “The Pegasus V Ultrafaint Dwarf Galaxy Newly Discovered Beyond Andromeda”, 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 Martínez-Delgado (Instituto de Astrofísica de Andalucía, Spain), Matteo Monelli (Spain). Instituto de Astrofísica de Canarias (IAC) and Universidad de La Laguna, Spain), Noushin Karim (Department of Physics, University of Surrey, UK), Giuseppe Donatiello (UAI – Unione Astrofili Italiani, Italy), Eric J. Tollerud (Space Telescope Science ) Institute, USA), Walter Boschin (Instituto de Astrofísica de Canarias (IAC), Universidad de La Laguna and Fundación G. Galilei – INAF (Telescopio Nazionale Galileo), Spain).