Eric Bell, an associate professor in astronomy, and Colin Slater, an astronomy Ph.D. student, found Andromeda XXVIII and XXIX---that's 28 and 29. They did it by using a tested star-counting technique on the newest data from the Sloan Digital Sky Survey, which has mapped more than a third of the night sky. They also used follow-up data from the Gemini North Telescope in Hawaii.
At 1.1 million and 600,000 light years from Andromeda, these are two of the furthest satellite galaxies ever detected. Invisible to the naked eye, the galaxies are 100,000 times fainter than Andromeda, and can barely be seen even with large telescopes.
The findings are published in the current Nov. 20 edition of Astrophysical Journal.
These astronomers set out looking for dwarf galaxies around Andromeda to help them understand how matter relates to dark matter, an invisible substance that doesn't emit or reflect light, but is believed to make up most of the universe's mass. Astronomers believe it exists because they can detect its gravitational effects on visible matter. With its gravity, dark matter is believed to be responsible for organizing visible matter into galaxies.
"These faint, dwarf, relatively nearby galaxies are a real battleground in trying to understand how dark matter acts at small scales," Bell said. "The stakes are high."
The prevailing hypothesis is that visible galaxies are all nestled in beds of dark matter, and each bed of dark matter has a galaxy in it. For a given volume of universe, the predictions match observations of large galaxies.
"But it seems to break down when we get to smaller galaxies," Slater said. "The models predict far more dark matter halos than we observe galaxies. We don't know if it's because we're not seeing all of the galaxies or because our predictions are wrong."
"The exciting answer," Bell said, "would be that there just aren't that many dark matter halos." Bell said. "This is part of the grand effort to test that paradigm."
The papers are titled, "Andromeda XXIX: A New Dwarf Spheroidal Galaxy 200 kpc from Andromeda," and Andromeda XXVIII: A Dwarf Galaxy more than 350 kpc from Andromeda."
The research is funded in part by the National Science Foundation.
For more information:Eric Bell: http://www.astro.lsa.umich.edu/~ericbell/
Abstract of Andromeda XXIX: A New Dwarf Spheroidal Galaxy 200 kpc from Andromeda: http://iopscience.iop.org/2041-8205/742/1/L15
Nicole Casal Moore | Newswise Science News
Double layer of graphene helps to control spin currents
18.10.2019 | University of Groningen
Analysis of Galileo's Jupiter entry probe reveals gaps in heat shield modeling
17.10.2019 | American Institute of Physics
A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)
It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.
The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...
Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.
Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...
A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.
The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...
Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).
Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...
02.10.2019 | Event News
02.10.2019 | Event News
19.09.2019 | Event News
18.10.2019 | Power and Electrical Engineering
18.10.2019 | Medical Engineering
18.10.2019 | Physics and Astronomy