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Sloan Digital Sky Survey IV - SDSS-III
Principal Data Scientist: Adam Bolton (University of Utah)
Welcome (Adam Bolton Joins NOAO) ...
Welcome (Adam Bolton Joins NOAO) NOAO welcomes Adam Bolton as the new Associate Director of the NOAO System Science and Data Center.
He brings to NOAO technical expertise in imaging and spectroscopic surveys that is motivated by his research interest in galaxies, dark matter, and dark energy.
Adam Bolton Joins NOAO as Associate Director for the NOAO System Science and Data Center
Adam Bolton, Associate Director, NOAO System Science and Data Center
NOAO welcomes Adam Bolton as the new Associate Director (AD) of the NOAO System Science and Data Center (NSSDC).
brings to NOAO broad and deep technical expertise in imaging and spectroscopic surveys that is motivated by his
research interest in galaxies, dark matter, and dark energy.
takes over from the outgoing NSSDC AD, Verne Smith.
Bolton comes to NOAO from a position as Associate Professor in the Department of Physics and Astronomy at the University of Utah, where he has been on the faculty since 2009.
previously held the Beatrice Watson Parrent postdoctoral fellowship at the University of Hawaii
(2007-2009) and a CfA Postdoctoral Fellowship at the Harvard-Smithsonian Center for Astrophysics
He received his PhD in Physics from MIT in 2005.
has extensive research experience in the analysis of astronomical imaging and spectroscopy, and in the application of new statistical methods to large surveys.
research interests include the use of strong gravitational lensing to measure the mass structure of galaxies, and the development of advanced spectroscopic analysis methods to enable and exploit new surveys of the universe beyond our own galaxy.
The Principal Data Scientist for the Sloan Digital Sky Survey
(SDSS) since 2012, Bolton
has also been a leader in proposing and designing the Dark Energy Spectroscopic Instrument (DESI), which is destined for the Mayall telescope on Kitt Peak, and its associated data management and analysis systems.
interest in and experience with large data sets will be an asset to NOAO
as it evolves to meet the changing needs of the astronomical community.
Adam is the right leader at the right time to help NOAO develop and deploy new services that the community can use to access and analyze large, rich catalogs of millions of objects across the entire celestial sphere."
Co-investigators on the grant are UM ...
Co-investigators on the grant are UM Associate Professor Dan Reisenfeld, also from the Department of Physics and Astronomy, and Adam Bolton, assistant professor of astrophysics at the University of Utah.
According to Dr. Adam Bolton, ...
According to Dr. Adam Bolton, lead author on the study, most recent research suggests that huge and old massive elliptical galaxies grow by snacking on many smaller galaxies through absorbing their mass in collisions.
But Bolton has a different idea, based on some previous research.
"We're suggesting that major collisions between massive galaxies are just as important as those many small snacks," he
In other words, eating big meals matters as much as snacking on smaller galaxies.
"I feel like if we can't explain why these galaxies look the way they do, we don't have any hope with other types of galaxies," Bolton
In order to study that possibility, Bolton
made use of data from another project he
is working on to map the sky using the Sloan Digital Sky Survey-III.
That project is trying to put together a 3D map of the universe, which would be useful for any number of reasons, including getting a better idea of early history close to the Big Bang as well as understanding the properties of dark energy, the mysterious stuff that makes the universe accelerate and makes up roughly 72 percent of the mass in the universe.
But a side benefit of mapping as many galaxies as you can is that it's possible to find galaxies that show gravitational lensing, a phenomenon that is very rare, perhaps showing up in only 1 in 100 galaxies, according to Bolton
It also allows you to measure mass.
This diagram shows briefly the principle behind gravity lensing that allowed scientists to measure the mass and density of elliptical galaxies.
Credit: Courtesy of Adam Bolton, University of Utah
When two galaxies are exactly superimposed from the view of Earth, with one much farther away, the gravity of the closer galaxy will bend the light from the distant one, making it look like a ring from our point of view.
The more bent the light is, the bigger the ring is and the more massive the closer galaxy is.
Once the team found a galaxy that showed lensing, they could point the Hubble Telescope at the galaxy and take very accurate readings of the mass of the galaxy and approximate where the mass is concentrated, accurate to about 2 percent, according to Bolton
"There's really no other way other than gravitational lensing to make precise measurement of galaxies this far away," he
In a new study, University of ...
In a new study, University of Utah astronomer Adam Bolton and colleagues measured these Einstein rings to determine the mass of 79 lens galaxies that are massive elliptical galaxies, the largest kind of galaxy with 100 billion stars.
This is evidence that big galaxies are crashing into other big galaxies to make even bigger galaxies," says astronomer Adam Bolton, principal author of the new study.
"Most recent studies have indicated that these massive galaxies primarily grow by eating lots of smaller galaxies," he
Bolton conducted the study with three other University of Utah astronomers - postdoctoral researcher Joel Brownstein, graduate student Yiping Shu and undergraduate Ryan Arneson - and with these members of the Sloan Digital Sky Survey: Christopher Kochanek, Ohio State University; David Schlegel, Lawrence Berkeley National Laboratory; Daniel Eisenstein, Harvard-Smithsonian Center for Astrophysics; David Wake, Yale University; Natalia Connolly, Hamilton College, Clinton, N.Y.; Claudia Maraston, University of Portsmouth, U.K.; and Benjamin Weaver, New York University.
"They are the end products of all the collisions and mergers of previous generations of galaxies," perhaps hundreds of collisions," Bolton
"But if you have two roughly comparable galaxies and they are on a collision course, each one penetrates more toward the center of the other, so more mass ends up in the center," Bolton
Other recent studies indicate stars are spread more widely within galaxies over time, supporting the idea that massive galaxies snack on much smaller ones.
"We're finding galaxies are getting more concentrated in their mass over time even though they are getting less concentrated in the light they emit," Bolton
believes large galaxy collisions explain the growing mass concentration, while galaxies gobbling smaller galaxies explain more starlight away from galactic centers.
"Both processes are important to explain the overall picture," Bolton
new study was "almost gravy" that accompanied an SDSS-III project named BOSS, for Baryon Oscillation Spectrographic Survey.
BOSS is measuring the history of the universe's expansion with unprecedented precision.
"The more distant galaxy sends out diverging light rays, but those that pass near the closer galaxy get bent into converging light rays that appear to us as of a ring of light around the closer galaxy," says Bolton
The greater the amount of matter in a lens galaxy, the bigger the ring.
That seems counterintuitive, but the larger mass pulls with enough gravity to make the distant star's light bend so much that lines of light cross as seen by the observer, creating a bigger ring.
If there is more matter concentrated near the center of a galaxy, the faster stars will be seen moving toward or being slung away from the galactic center, Bolton
and colleagues acknowledge their observations might be explained by theories other than the idea that galaxies are getting denser in their centers over time:
Gas that is collapsing to form stars can increase the concentration of mass in a galaxy.
argues the stars in these galaxies are too old for that explanation to work.
Gravity from the largest massive galaxies strips neighboring "satellite" galaxies of their outskirts, leaving more mass concentrated in the centers of the satellite galaxies.
contends that process is not likely to produce the concentration of mass observed in the new study and explain how the extent of that central mass increases over time.
The researchers merely detected the boundary in each galaxy between the star-dominated inner regions and the outer regions, which are dominated by unseen dark matter.
Under this hypothesis, the appearance of growing galaxy mass concentration over time is due to a coincidence in researchers' measurement method, namely that they are measuring younger galaxies farther from their centers and measuring older galaxies closer to their centers, giving an illusion of growing mass concentration in galactic centers over time.
says this measurement difference is too minor to explain the observed pattern of matter density within the lens galaxies.