Using light from the Big Bang, an international team led by Cornell and the Lawrence Berkeley National Laboratory of the U.S. Department of Energy have begun revealing the material that feeds galactic formation.
“There is uncertainty about the formation of stars within galaxies that theoretical models are unable to predict,” said lead author Stefania Amodeo, Cornell’s postdoctoral researcher in astronomy at the College of Arts and Sciences (A&S), who is currently researching at the Observatory. of Strasbourg, France. “With this work, we are providing tests for models of galactic formation to understand galactic and stellar formation.”
The research “Atacama Cosmology Telescope: Modeling the Gas Thermodynamics in BOSS CMASS galaxies from Kinematic and Thermal Sunyaev-Zel’dovich Measurements”, appears in the March 15, 2021, edition of Physical Review D.
Proto-galaxies are always full of gas and as they cool, the galaxies begin to form, said senior author Nick Battaglia, an assistant professor of astronomy at A&S. “If we just did a count of a back envelope, gas would be transformed into stars,” he said. “But it doesn’t.”
Galaxies are inefficient when they make stars, Battaglia said. “About 10% of the gas – at most – in any galaxy becomes stars,” he explained, “and we want to know why.”
Scientists can now verify their long-standing theoretical work and simulations by looking at microwave observations with data and applying a mathematical equation from the 1970s. They looked at data from the Atacama Cosmology Telescope (ACT) – which observes the static full radiation of the cosmic microwave background (CMB) of the Big Bang – and looked for the Sunyaev-Zel’dovich effects. This combination of data enables scientists to map the surrounding material, which indicates the formation of galaxies at various stages.
“How do galaxies form and evolve in our universe?” Battaglia said. “Given the nature of astronomy, we can’t sit back and watch how a galaxy evolves. We use various telescopic snapshots of galaxies – and each has its own evolution – and we try to put that information together. From there, we can extrapolate Milky Way formed. “
Scientists are effectively using the cosmic microwave background – remnants of the Big Bang – as a backlit screen, which is 14 billion years old, to find this material around galaxies.
“It looks like a watermark on a banknote,” said co-author Emmanuel Schaan, the chamber postdoctoral fellow at the Lawrence Berkeley National Laboratory. “If you put it in front of a backlight, then the watermark appears as a shadow. For us, the backlight is the cosmic microwave background. It serves to illuminate the gas from behind, so we can see the shadow as the CMB light passes through that gas. “
Along with Simone Ferraro, a section guy at Lawrence Berkeley, Schaan led the measurement part of the project.
“We make these measurements of this galactic material at distances from galactic centers never before done,” Battaglia said. “These new observations are pushing the field.”
Reference: “Atacama Cosmological Telescope: Modeling the gas thermodynamics in galaxies BOSS CMASS from kinematic and thermal measurements Sunyaev-Zel’dovich” by
Stefania Amodeo et al., March 15, 2021, Physical Review D.
DOI: 10.1103 / PhysRevD.103.063514
In addition to researchers from Battaglia, Amodeo, Cornell includes doctoral students Emily Moser, Victoria Calafut, Eve Vavagiakis; Steve K. Choi, a postdoctoral fellow of the National Science Foundation at the Cornell Center for Astrophysics and Planetary Astronomy; Rachel Bean, professor of astronomy and senior dean at A&S; and Mike Niemack, associate professor of physics and astronomy at A&S.
The ACT team is an international collaboration, with scientists from 41 institutions in seven countries.
In addition to the National Science Foundation’s Atacama Cosmology Telescope, the work was supported by the Baryon Oscillation Spectroscopic Survey in New Mexico, where the Berkeley Lab played a major role; the European Space Agency’s Planck telescope and the Herschel space telescope; and the Cori supercomputer at the National Energy Research Science Computer Center of Berkeley Lab.
A grant from the National Astronomical and Astrophysics Science Foundation funded the research.