New COMAP radio survey will peer beneath the “tip of the iceberg” of galaxies to unveil a hidden period of star formation.
Someday round 400 million years after the delivery of our universe, the primary stars started to type. This marked the top of the universe’s so-called darkish ages, and a brand new light-filled period started. Over time, an increasing number of galaxies started to take form and served as factories for churning out new stars. This course of reached a peak roughly 4 billion years after the Massive Bang.
Fortunately for astronomers, this bygone period can nonetheless be noticed. Distant gentle takes time to succeed in us, and highly effective telescopes can decide up gentle emitted by galaxies and stars billions of years in the past (our universe is 13.8 billion years outdated). Nonetheless, the small print of this chapter in our universe’s historical past are fuzzy as a result of many of the stars being shaped on the time are faint and hidden by mud.
A brand new Caltech undertaking, referred to as COMAP (CO Mapping Array Venture), will current us with a brand new glimpse into this epoch of galaxy meeting. It’ll assist reply questions on what actually precipitated the universe’s speedy enhance within the manufacturing of stars.
“Most devices would possibly see the tip of an iceberg when taking a look at galaxies from this era,” says Kieran Cleary, the undertaking’s principal investigator and the affiliate director of Caltech’s Owens Valley Radio Observatory (OVRO). “However COMAP will see what lies beneath, hidden from view.”
Within the present section of the undertaking, the ten.4-meter “Leighton” radio dish at OVRO is getting used to review the most typical sorts of star-forming galaxies unfold throughout area and time. This contains these which might be too troublesome to view in different methods as a result of they’re too faint or hidden by mud. The radio observations hint chilly hydrogen gasoline, the uncooked materials from which stars are made. This gasoline shouldn’t be simple to pinpoint straight, so as a substitute COMAP measures vibrant radio indicators from carbon monoxide (CO) gasoline, which is at all times current together with the hydrogen. COMAP’s radio digicam is essentially the most highly effective ever constructed to detect these radio indicators.
The primary science outcomes from the undertaking have simply been printed in seven papers in The Astrophysical Journal. Primarily based on observations taken one 12 months right into a deliberate five-year survey, COMAP set higher limits on how a lot chilly gasoline should be current in galaxies on the epoch being studied, together with those which might be usually too faint and dusty to see. Whereas the undertaking has not but made a direct detection of the CO sign, these early outcomes exhibit that it’s on monitor to take action by the top of the preliminary five-year survey and in the end will paint essentially the most complete image but of the universe’s historical past of star formation.
“Seeking to the way forward for the undertaking, we goal to make use of this system to successively look additional and additional again in time,” Cleary says. “Beginning 4 billion years after the Big Bang, we will keep pushing back in time until we reach the epoch of the first stars and galaxies, a couple of billion years earlier.”
Anthony Readhead, the co-principal investigator and the Robinson Professor of Astronomy, Emeritus, says that COMAP will see not only the first epoch of stars and galaxies, but also their epic decline. “We will observe star formation rising and falling like an ocean tide,” he says.
COMAP works by capturing blurry radio images of clusters of galaxies over cosmic time rather than sharp images of individual galaxies. This blurriness enables the astronomers to efficiently catch all the radio light coming from a larger pool of galaxies, even the faintest and dustiest ones that have never been seen.
“In this way, we can find the average properties of typical, faint galaxies without needing to know very precisely where any individual galaxy is located,” explains Cleary. “This is like finding the temperature of a large volume of water using a thermometer rather than analyzing the motions of the individual water molecules.”
These findings are the subject of a Focus Issue in the Astrophysical Journal, which contains links to the published papers.
The project has received funding from the Keck Institute for Space Studies (for critical early technology development) and from the National Science Foundation (NSF), for building the “Pathfinder” early phase of the project and performing the survey. The project is a collaboration between Caltech; the Jet Propulsion Laboratory (JPL), which is managed by Caltech for NASA; New York University; Princeton University; Stanford University; Université de Genève; University of Oslo; The University of Manchester; University of Maryland; University of Miami; and the University of Toronto (including the Canadian Institute for Theoretical Astrophysics and the Dunlap Institute for Astronomy and Astrophysics).