John Mulchaey is the director and the Crawford H. Greenewalt Chair of the Carnegie Observatories. He investigates groups and clusters of galaxies, elliptical galaxies, dark matter—the invisible material that makes up most of the universe—active galaxies and black holes. He is also a scientific editor for The Astrophysical Journal and is actively involved in public outreach and education.

Most galaxies including our own Milky Way, exist in collections known as groups, which are the most common galaxy systems and are important laboratories for studying galaxy formation and evolution. Mulchaey studies galaxy groups to understand the processes that affect most galaxies during their lifetimes.

As a graduate student, Mulchaey led the team that discovered that some groups are bright X-ray sources. The extent of the emission suggests that the X-rays originated in a very hot, low-density gas called the intragroup medium. X-ray observations of the medium have shown that the temperature is a scorching 10 million degrees. Temperatures this high should quickly disperse; but the intragroup medium does not. Astronomers believe that gravity is binding it. However, the mass required to confine the gas is much higher than the visible group mass. This suggests that galaxy groups are dominated by that elusive material called dark matter, which does not emit light but has a strong gravitational pull.

Although Mulchaey works extensively with space-based, X-ray telescopes, the optical telescopes at Carnegie’s Las Campanas Observatory play a central role in his research. X-ray images alone are not sufficient to uncover the nature of galaxy groups. Follow-up observations with large-aperture optical telescopes, such as Magellan, are necessary to determine galaxy type and distance.

The large Magellan telescopes have allowed Mulchaey to study distant galaxy groups for the first time. He is directly tracing how the group environment affects properties of individual galaxies. These observations suggest that galaxy-galaxy merging is very common in groups. For some groups, the galaxies may continue merging until they form a single massive galaxy. In the last few years, Mulchaey has uncovered several of these “fossil group” systems. Studies of them are proving to have important clues into the likely end state of most groups, including the Local Group, where our Milky Way resides.

Mulchaey received his B.S. in astrophysics from UC-Berkeley and his Ph. D. from the University of Maryland. He was a fellow at the Space Telescope Science Institute and at Carnegie before joining the  Carnegie staff. For more information see http://obs.carnegiescience.edu/users/mulchaey

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Patrick McCarthy courtesy of GMTO
October 1, 2019

Pasadena, CA—Carnegie astronomer and Vice President of the Giant Magellan Telescope (GMT), Patrick McCarthy, has been appointed as the first Director of the National Science Foundation’s newly formed National Optical-Infrared Astronomy Research Laboratory (NSF’s OIR Lab).

McCarthy has been a member of the GMT project since its inception 15 years ago, helping to bring it from a sketch on a napkin to a 100-plus person organization with 12 U.S. and international partners. In 2008, 20 years into his tenure at Carnegie, McCarthy officially expanded his role when he accepted his current leadership position at GMT.

Working with then-Carnegie Observatories

lustración por Robin Dienel, cortesía de Carnegie Institution for Science.
September 26, 2019

Washington, DC—El satélite Transiting Exoplanet Survey Satellite (TESS) de la NASA ha observado por primera vez las secuelas de una estrella que fue violentamente desgarrada por un agujero negro supermasivo. El haber capturado en pleno desarrollo un evento tan poco común ayudará a los astrónomos a entender estos misteriosos fenómenos.

Las observaciones fueron publicadas en la revista científica The Astrophysical Journal y el estudio fue liderado por el astrónomo de la Institución Carnegie, Thomas Holoien. Holoien es uno de los miembros fundadores de la red internacional de telescopios que realizó el

Illustration of a TDE by Robin Dienel, courtesy of Carnegie Science
September 26, 2019

Pasadena, CA—NASA’s Transiting Exoplanet Survey Satellite (TESS) has for the first time seen the aftermath of a star that was violently ripped apart by a supermassive black hole. Catching such a rare event in action will help astronomers understand these mysterious phenomena.  

The observation is reported in The Astrophysical Journal by a team of astronomers led by Carnegie’s Thomas Holoien, who is a founding member of the international network of telescopes that made the discovery—the Ohio State University based All-Sky Automated Survey for Supernovae (ASAS-SN).

Tidal disruption events, or TDEs, occur when a star gets too close to a

Decker French
July 24, 2019

Pasadena, CA— Carnegie’s K. Decker French was recognized by the Astronomical Society of the Pacific with its Robert J. Trumpler Award, which is presented to a recent Ph.D. graduate “whose research is considered unusually important to astronomy.” French completed her doctorate at the University of Arizona Tucson in 2017 and is currently a Hubble Fellow at the Carnegie Observatories.

Her research focuses on a radio survey of the gas clouds within galaxies that have recently ended the star-forming phase of their evolution.  The lack of star formation in these galaxies has long been assumed to be caused by a depletion of the cold, dense molecular gases

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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

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

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/

Staff Associate Kamena Kostova joined the Department of Embryology in November 2018. She studies ribosomes, the factory-like structures inside cells that produce proteins. Scientists have known about ribosome structure, function, and biogenesis for some time. But, a major unanswered question is how cells monitor the integrity of the ribosome itself. Problems with ribosomes have been associated with diseases including neurodegeneration and cancer. The Kostova lab investigates the fundamental question of how cells respond when their ribosomes break down using mass spectrometry, functional genomics methods, and CRISPR genome editing.

Kostova received a B.S. in Biology from the

Sally June Tracy applies cutting-edge experimental and analytical techniques to understand the fundamental physical behavior of materials at extreme conditions. She uses dynamic compression techniques with high-flux X-ray sources to probe the structural changes and phase transitions in materials at conditions that mimic impacts and the interiors of terrestrial and exoplanets. She is also an expert in nuclear resonant scattering and synchrotron X-ray diffraction. She uses these techniques to understand novel behavior at the electronic level.  Tracy received her Ph.D. from the California Institute of

The Ludington lab investigates complex ecological dynamics from microbial community interactions using the fruit fly  Drosophila melanogaster. The fruit fly gut carries numerous microbial species, which can be cultured in the lab. The goal is to understand the gut ecology and how it relates to host health, among other questions, by taking advantage of the fast time-scale and ease of studying the fruit fly in controlled experiments. 

Nick Konidaris is a staff scientist at the Carnegie Observatories and Instrument Lead for the SDSS-V Local Volume Mapper (LVM). He works on a broad range of new optical instrumentation projects in astronomy and remote sensing. Nick's projects range from experimental to large workhorse facilities. On the experimental side, he recently began working on a new development platform for the 40-inch Swope telescope at Carnegie's Las Campanas Observatory that will be used to explore and understand the explosive universe.

 Nick and his colleagues at the Department of Global Ecology are leveraging the work on Swope to develop a new airborne spectrograph that will be