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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June 28, 2022

Washington, DC—The violent event that likely preceded our Solar System’s formation holds the solution to a longstanding meteorite mystery, says new work from Carnegie’s Alan Boss published in The Astrophysical Journal.

The raw material from which our Solar System was constructed was dispersed when the shock wave from an exploding supernova injected material into a cloud of dust and gas, causing it to collapse in on itself. In the aftermath of this event, most of the injected matter was gravitationally drawn into the center of the whirlwind, where the intense buildup of pressure enabled nuclear fusion to commence, and the Sun was born. The young star was

Los telescopios Magallanes del Observatorio Las Campanas. Crédito: Leon Aslan.
June 15, 2022

Pasadena, CA- Los ancestros de algunos de los mayores cúmulos de galaxias han estado ocultos a plena vista. Un nuevo trabajo dirigido por Andrew Newman, de Carnegie, demuestra una nueva técnica para identificar los precursores de los entornos galácticos más extremos. Los hallazgos del equipo fueron publicados en Nature. 

Al igual que todos nosotros, las galaxias están formadas y moldeadas por su entorno. Para obtener una imagen completa de las diversas influencias físicas en el ciclo de vida de una galaxia, es crucial rastrear la aparición de propiedades causadas por factores ambientales a medida que surgen.

"Hace

Star trails over the Magellan telescopes at Las Campanas courtesy Leon Aslan.
June 15, 2022

Pasadena, CA— The ancestors of some of the largest galaxy clusters have been hiding in plain sight. New work led by Carnegie’s Andrew Newman demonstrates a new technique for identifying the precursors of the most extreme galactic environments. The team’s findings are published in Nature.  

Like all of us, galaxies are shaped and molded by their surroundings. To obtain a complete picture of the various physical influences on a galaxy’s lifecycle, it’s crucial to trace the emergence of properties caused by environmental factors as they arise.

“We’ve known for a long time that the colors, masses, and shapes of galaxies depend on

Andrómeda cortesía de la NASA/Bill Cook.
June 13, 2022

Pasadena, CA- Un análisis detallado de la composición y el movimiento de más de 500 estrellas reveló pruebas concluyentes de una antigua colisión entre Andrómeda y una galaxia vecina. Los hallazgos, que mejoran nuestra comprensión de los acontecimientos que dan forma a la evolución de las galaxias, fueron presentados por Ivanna Escala, de Carnegie, el lunes en la reunión de la Sociedad Astronómica Americana.

Las galaxias crecen por acumulación de material procedente de objetos cercanos -otras galaxias y densas agrupaciones de estrellas llamadas cúmulos globulares-, a menudo tras un choque catastr

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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/

Ana Bonaca is Staff Member at Carnegie Observatories. Her specialty is stellar dynamics and her research aims to uncover the structure and evolution of our galaxy, the Milky Way, especially the dark matter halo that surrounds it. In her research, she uses space- and ground-based telescopes to measure the motions of stars, and constructs numerical experiments to discover how dark matter affected them.

She arrived in September 2021 from Harvard University where she held a prestigious Institute for Theory and Computation Fellowship. 

Bonaca studies how the uneven pull of our galaxy’s gravity affects objects called globular clusters—spheres made up of a million

Peter Gao's research interests include planetary atmospheres; exoplanet characterization; planet formation and evolution; atmosphere-surface-interior interactions; astrobiology; habitability; biosignatures; numerical modeling.

His arrival in September 2021 continued Carnegie's longstanding tradition excellence in exoplanet discovery and research, which is crucial as the field prepares for an onslaught of new data about exoplanetary atmospheres when the next generation of telescopes come online.

Gao has been a part of several exploratory teams that investigated sulfuric acid clouds on Venus, methane on Mars, and the atmospheric hazes of Pluto. He also

Anne Pommier's research is dedicated to understanding how terrestrial planets work, especially the role of silicate and metallic melts in planetary interiors, from the scale of volcanic magma reservoirs to core-scale and planetary-scale processes.

She joined Carnegie in July 2021 from U.C. San Diego’s Scripps Institution of Oceanography, where she investigated the evolution and structure of planetary interiors, including our own Earth and its Moon, as well as Mars, Mercury, and the moon Ganymede.

Pommier’s experimental petrology and mineral physics work are an excellent addition to Carnegie’s longstanding leadership in lab-based mimicry of the

Johanna Teske became the first new staff member to join Carnegie’s newly named Earth and Planets Laboratory (EPL) in Washington, D.C., on September 1, 2020. She has been a NASA Hubble Fellow at the Carnegie Observatories in Pasadena, CA, since 2018. From 2014 to 2017 she was the Carnegie Origins Postdoctoral Fellow—a joint position between Carnegie’s Department of Terrestrial Magnetism (now part of EPL) and the Carnegie Observatories.

Teske is interested in the diversity in exoplanet compositions and the origins of that diversity. She uses observations to estimate exoplanet interior and atmospheric compositions, and the chemical environments of their formation