Josh Simon uses observations of nearby galaxies to study problems related to dark matter, chemical evolution, star formation, and the process of galaxy evolution.

In one area he looks at peculiarly dark galaxies. Interestingly, some galaxies are so dark they glow with the light of just a few hundred Suns. Simon and colleagues have determined that a tiny, very dim galaxy orbiting the Milky Way, called Segue 1, is the darkest galaxy ever found and has the highest dark matter density ever found. His team has also laid to rest a debate about whether Segue 1 really is a galaxy or a globular cluster—a smaller group of stars that lacks dark matter. Their findings make Segue 1 a promising laboratory to study dark matter, particularly the possibility that dark matter could be seen for the first time via a detection of gamma rays emanating from colliding dark matter particles.

Dark matter is the mysterious nonluminous material that makes up about most of the universe.  Dark energy is a mysterious repulsive force. Together they make up  about 95% of the universe. The rest--all observable matter--adds up to less than 5% of the universe.  Nearby dwarf galaxies have the highest measured densities of dark matter, making them ideal for dark matter studies, but that proximity also has a downside. Star systems so close to the massive Milky Way are subject to the acceleration of their stars by our galaxy’s tidal forces, an effect that can mimic the presence of dark matter. The lack of bright stars in dim dwarfs also makes it difficult to measure the velocities of enough stars for sufficient certainty. Simon and company overcame these hurdles with a comprehensive program that measured and analyzed the speed and chemistry of 397 stars in the vicinity of Segue 1.

 A major difference between galaxies and globular clusters--spherical collections of stars that are gravitationally bound--is that the stars in galaxies contain widely varying amounts of iron and other heavy elements, while stars in clusters do not. The new observations revealed that some Segue 1 stars have 50 times less iron than others in the galaxy, demonstrating conclusively that Segue 1 cannot be a globular cluster.

In collaboration with astronomers, Simon also showed that the high speeds of the Segue 1 stars are not caused by invisible binary companion stars, firming up the estimates of the amount of dark matter in the galaxy. Ongoing observations with NASA’s Fermi Gamma-ray Space Telescope are searching for signals from Segue 1 and other dwarfs, which would provide astronomers with concrete proof that their dark matter theories are on the right track\

Simon received his B.S. in physics from Stanford University and his M.A. and Ph. D. in astrophysics from UC-Berkeley. He was a postdoctoral scholar at Caltech from 2005-2008 and  the Vera Rubin Fellow at Carnegie from  2008 to 2010. For more information see http://obs.carnegiescience.edu/users/jsimon

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Carnegie Science, Carnegie Institution, Carnegie Institution for Science, Robin Dienel, SDSS-V, Sloan Digital Sky Survey
November 16, 2017

Pasadena, CA— The next generation of the Sloan Digital Sky Survey (SDSS-V), directed by Carnegie’s Juna Kollmeier, will move forward with mapping the entire sky following a $16 million grant from the Alfred P. Sloan Foundation. The grant will kickstart a groundbreaking all-sky spectroscopic survey for a next wave of discovery, anticipated to start in 2020.

The Sloan Digital Sky Survey has been one of the most-successful and influential surveys in the history of astronomy, creating the most-detailed three-dimensional maps of the universe ever made, with deep multi-color images of one third of the sky, and spectra for more than three million astronomical objects.

“For more

Carnegie Science, Carnegie Institution, Carnegie Institution for Science, European Southern Observatory, ESO/M. Kornmesser
November 8, 2017

Pasadena, CA— It’s the celestial equivalent of a horror movie villain—a star that wouldn’t stay dead.

An international team of astronomers including Carnegie’s Nick Konidaris and Benjamin Shappee discovered a star that exploded multiple times over a period of 50 years. The finding, published by Nature, completely confounds existing knowledge of a star’s end of life, and Konidaris’ instrument-construction played a crucial role in analyzing the phenomenon.  

In September 2014, the intermediate Palomar Transient Factory team of astronomers detected a new explosion in the sky, iPTF14hls.

The light given off by the event was analyzed in order to understand the speed and

Carnegie Science, Carnegie Institution, Carnegie Institution for Science, Giant Magellan Telescope Organization, GMTO
November 3, 2017

Pasadena, CA—The Giant Magellan Telescope Organization (GMTO) today announced that it has initiated the casting of the fifth of seven mirrors that will form the heart of the Giant Magellan Telescope (GMT). The mirror is being cast at the University of Arizona's Richard F. Caris Mirror Laboratory, the facility known for creating the world’s largest mirrors for astronomy. The 25-meter diameter GMT will be sited at Carnegie's Las Campanas Observatory in the Chilean Andes and will be used to study planets around other stars and to look back to the time when the first galaxies formed. The process of “casting” the giant mirror involves melting nearly 20 tons of glass in a spinning furnace.

Carnegie Science, Carnegie Institution, Carnegie Institution for Science,
October 14, 2017

Washington, DC— On August 17, a team of four Carnegie astronomers provided the first-ever glimpse of two neutron stars colliding, opening the door to a new era of astronomy.  

Along with colleagues at UC Santa Cruz, the team used the Swope telescope at Las Campanas Observatory to discover the light produced by the merger, pinpointing the origin of a gravitational wave signal less than 11 hours after it was detected.  They also obtained the earliest spectra of the collision, which may allow them to explain how many of the universe’s heavy elements were created—a decades old question for astrophysicists.

Their discovery, named Swope Supernova Survey 2017a (or SSS17a), is

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The fund supports a postdoctoral fellowship in astronomy that rotates between the Carnegie Science departments of Terrestrial Magnetism in Washington, D.C., and the Observatories in Pasadena California. 

The Earthbound Planet Search Program has discovered hundreds of planets orbiting nearby stars using telescopes at Lick Observatory, Keck Observatory, the Anglo-Australian Observatory, Carnegie's Las Campanas Observatory, and the ESO Paranal Observatory.  Our multi-national team has been collecting data for 30 years, using the Precision Doppler technique.  Highlights of this program include the detection of five of the first six exoplanets, the first eccentric planet, the first multiple planet system, the first sub-Saturn mass planet, the first sub-Neptune mass planet, the first terrestrial mass planet, and the first transit planet.Over the course of 30 years we have improved the

The Giant Magellan Telescope will be one member of the next class of super giant earth-based telescopes that promises to revolutionize our view and understanding of the universe. It will be constructed in the Las Campanas Observatory in Chile. Commissioning of the telescope is scheduled to begin in 2021.

The GMT has a unique design that offers several advantages. It is a segmented mirror telescope that employs seven of today’s largest stiff monolith mirrors as segments. Six off-axis 8.4 meter or 27-foot segments surround a central on-axis segment, forming a single optical surface 24.5 meters, or 80 feet, in diameter with a total collecting area of 368 square meters. The GMT will

Along with Alycia Weinberger and Ian Thompson, Alan Boss has been running the Carnegie Astrometric Planet Search (CAPS) program, which searches for extrasolar planets by the astrometric method, where the planet's presence is detected indirectly through the wobble of the host star around the center of mass of the system. With over eight years of CAPSCam data, they are beginning to see likely true astrometric wobbles beginning to appear. The CAPSCam planet search effort is on the verge of yielding a harvest of astrometrically discovered planets, as well as accurate parallactic distances to many young stars and M dwarfs. For more see  http://instrumentation.obs.carnegiescience.edu/ccd/caps.

Leopoldo Infante became the director of the Las Campanas Observatory on July 31, 2017.

Since 2009, Infante has been the founder and director of the Centre for Astro-Engineering at the Chilean university. He joined PUC as an assistant professor in 1990 and has been a full professor since 2006. He was one of the creators of PUC’s Department of Astronomy and Astrophysics, and served as its director from 2000 to 2006. He also established the Chilean Astronomical Society (SOCHIAS) and served as its president from 2009 to 2010.

Infante received his B.Sc. in physics at PUC. He then acquired a MSc. and Ph.D. in physics and astronomy from the University of Victoria in Canada.

Guillermo Blanc wants to understand the processes by which galaxies form and evolve over the course of the history of the universe. He studies local galaxies in the “present day” universe as well as very distant and therefore older galaxies to observe the early epochs of galaxy evolution. Blanc conducts a series of research projects on the properties of young and distant galaxies, the large-scale structure of the universe, the nature of Dark Energy—the mysterious repulsive force, the process of star formation at galactic scales, and the measurement of chemical abundances in galaxies.

To conduct this work, he takes a multi-wavelength approach including observations in the UV,

Peter van Keken studies the thermal and chemical evolution of the Earth. In particularly he looks at the causes and consequences of plate tectonics; element modeling of mantle convection,  and the dynamics of subduction zones--locations where one tectonic plate slides under another. He also studies mantle plumes; the integration of geodynamics with seismology; geochemistry and mineral physics. He uses parallel computing and scientific visualization in this work.

He received his BS and Ph D from the University of Utrecht in The Netherlands. Prior to joining Carnegie he was on the faculty of the University of Michigan.

Peter Driscoll studies the evolution of Earth’s core and magnetic field including magnetic pole reversal. Over the last 20 million or so years, the north and south magnetic poles on Earth have reversed about every 200,000, to 300,000 years and is now long overdue. He also investigates the Earth’s inner core structure; core-mantle coupling; tectonic-volatile cycling; orbital migration—how Earth’s orbit moves—and tidal dissipation—the dissipation of tidal forces between two closely orbiting bodies. He is also interested in planetary interiors, dynamos, upper planetary atmospheres and exoplanets—planets orbiting other stars. He uses large-scale numerical simulations in much of his research