Nav: Home

Tracing aromatic molecules in the early universe

March 22, 2017

RIVERSIDE, Calif. -- A molecule found in car engine exhaust fumes that is thought to have contributed to the origin of life on Earth has made astronomers heavily underestimate the amount of stars that were forming in the early Universe, a University of California, Riverside-led study has found.

That molecule is called polycyclic aromatic hydrocarbon (PAH). On Earth it is also found in coal and tar. In space, it is a component of dust, which along with gas, fills the space between stars within galaxies.

The study, which was just published in the Astrophysical Journal, represents the first time that astronomers have been able to measure variations of PAH emissions in distant galaxies with different properties. It has important implications for the studies of distant galaxies because absorption and emission of energy by dust particles can change astronomers' views of distant galaxies.

"Despite the ubiquity of PAHs in space, observing them in distant galaxies has been a challenging task," said Irene Shivaei, a graduate student at UC Riverside, and leader of the study. "A significant part of our knowledge of the properties and amounts of PAHs in other galaxies is limited to the nearby universe."

The research was conducted as part of the University of California-based MOSDEF survey, a study that uses the Keck telescope in Hawaii to observe the content of about 1,500 galaxies when the universe was 1.5 to 4.5 billion years old. The researchers observed the emitted visible-light spectra of a large and representative sample of galaxies during the peak-era of star formation activity in the universe.

In addition, the researchers incorporated infrared imaging data from the NASA Spitzer Space Telescope and the European Space Agency-operated Herschel Space Observatory to trace the polycyclic aromatic hydrocarbon emission in mid-infrared bands and the thermal dust emission in far-infrared wavelengths.

The researchers concluded that the emission of polycyclic aromatic hydrocarbon molecules is suppressed in low-mass galaxies, which also have a lower fraction of metals, which are atoms heavier than hydrogen and helium. These results indicate that the polycyclic aromatic hydrocarbon molecules are likely to be destroyed in the hostile environment of low-mass and metal-poor galaxies with intense radiation.

The researchers also found that the polycyclic aromatic hydrocarbon emission is relatively weaker in young galaxies compared to older ones, which may be due to the fact that polycyclic aromatic hydrocarbon molecules are not produced in large quantities in young galaxies.

They found that the star-formation activity and infrared luminosity in the universe 10 billion years ago is approximately 30 percent higher than previously measured.

Studying the properties of the polycyclic aromatic hydrocarbon mid-infrared emission bands in distant universe is of fundamental importance to improving our understanding of the evolution of dust and chemical enrichment in galaxies throughout cosmic time. The planned launch of the James Webb Space Telescope in 2018 will push the boundaries of our knowledge on dust and polycyclic aromatic hydrocarbon in the early universe.
-end-
The Astrophysical Journal paper is called "The MOSDEF Survey: Metallicity Dependence of PAH Emission at High Redshift and Implications for 24 μm Inferred IR Luminosities and Star Formation Rates at z ∼ 2."

In addition to Shivaei, the authors are: Naveen Reddy, Brian Siana, and Bahram Mobasher, of UC Riverside; Alice Shapley and Ryan L. Sanders, of UCLA; Mariska Kriek, Sedona H. Price, and Tom Zick, of UC Berkeley; and Alison L. Coil and Mojegan Azadi, of UC San Diego.

Mario De Leo-Winkler, a postdoctoral researcher in the UCR Department of Physics and Astronomy, made significant contributions to this article.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is now nearly 23,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion. A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. UCR also has ISDN for radio interviews. To learn more, call (951) UCR-NEWS.

University of California - Riverside

Related Astronomers Articles:

Astronomers unveil 'heart' of Eta Carinae
An international team of astronomers has imaged the Eta Carinae star system -- a colossal binary system that consists of two massive stars orbiting each other -- including a region between the two stars in which extremely high-velocity stellar winds are colliding.
Astronomers capture best view ever of disintegrating comet
Astronomers have captured the sharpest, most detailed observations of a comet breaking apart 67 million miles from Earth, using NASA's Hubble Space Telescope.
Astronomers find the first 'wind nebula' around a magnetar
Astronomers have discovered a vast cloud of high-energy particles called a wind nebula around a rare ultra-magnetic neutron star, or magnetar, for the first time.
Astronomers discover 'young Jupiter' exoplanet
The first planet detected by the Gemini Planet Imager is 100 light-years away but shares many of the characteristics of an early Jupiter.
Astronomers discover 'young Jupiter' exoplanet
A team of astronomers that includes University of Georgia professor Inseok Song has discovered a Jupiter-like planet within a young star system that could serve as a decoder ring for understanding how planets formed around the sun.
Astronomers discover 'young Jupiter' exoplanet
An international team of scientists that includes Travis Barman and Katie Morzinski from the University of Arizona has discovered a new exoplanet using the latest planet-hunting tool, the Gemini Planet Imager.
Astronomers discover 'young Jupiter' exoplanet
Astronomers have discovered a Jupiter-like planet within a young system that could serve as a decoder ring for understanding how planets formed around our sun.
Astronomers discover 'young Jupiter' exoplanet
Discovery of a Jupiter-like planet within a young system that could serve as a decoder ring for understanding how planets formed around our Sun.
Astronomers explain why a star is so hot right now
Astronomers have solved a mystery over small, unusually hot blue stars, 10 times hotter than our Sun, that are found in the middle of dense star clusters.
Astronomers unveil the farthest galaxy
An international team of astronomers led by Yale University and the University of California-Santa Cruz have pushed back the cosmic frontier of galaxy exploration to a time when the universe was only 5 percent of its present age.

Related Astronomers Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...