Astronomers Observe The Most Distant Galaxy In Plain Sight

  • MAMBO-9 is the most distant galaxy that has ever been detected without using a gravitational lens.  
  • It was observed directly via the Atacama Large Millimeter/submillimeter Array. 
  • The galaxy was formed just 970 million years after the Big Bang.

Since dust is a byproduct of star formation, the ubiquity of galaxies with high star formation means that dust-rich systems were common and dominated the cosmic star-forming process for several billion years after the Big Bang.

The detection of these dusty star-forming galaxies has been proven extremely difficult. They tend to be very faint and their distance determinations are subject to errors.

Although all such distant galaxies were formed in the early universe, researchers have managed to identify several of them as seen when our universe was less than a billion years old.

Recently, astronomers at the University of Texas at Austin spotted the light coming from a very old galaxy that was formed just 970 million years after the Big Bang. It is the most distant galaxy that has ever been detected without using a gravitational lens.

The galaxy, named MAMBO-9, is observed via the Atacama Large Millimeter/submillimeter Array (ALMA), the most complex astronomical observatory consisting of 66 radio telescopes in northern Chile. It is specifically developed to detect dusty star-forming galaxies that formed early in the history of the universe.

Such old, dusty galaxies exhibit extreme behavior and play a crucial role in the evolution of the universe. But since their starlight is hidden in intense cloud dust, it’s very difficult to detect them, even with advanced systems.

What Makes This Discovery Special?

Although Max-Planck Millimeter Bolometer array installed on the Plateau de Bure Interferometer (in France) and the IRAM 30-meter telescope (in Spain) already detected light coming MAMBO-9 a decade ago, the data wasn’t detailed enough to determine the distance of the galaxy. Also, the observations couldn’t be replicated with other telescopes.

ALMA’s higher sensitivity and higher resolution than earlier submillimeter telescopes, on the other hand, allowed researchers to reveal the distance of MAMBO-9. It is the most expensive ground-based telescope operating since 2013.

Reference: The Astrophysical Journal | DOI:10.3847/1538-4357/ab52ff | University of Texas

What’s unique about this observation is that this is the farthest dusty galaxy researchers have ever detected in an unobstructed way.

Usually, the light coming from the farthest galaxies is affected by other galaxies closer to the Milky Way: they bend the light from the more distant galaxy, causing gravitational lensing. Although the lensing effect makes it simple for instruments to detect distant astronomical bodies, it distorts the picture of the body.

Most Distant GalaxyALMA radio image of the MAMBO-9 | Courtesy of researchers 

In this case, astronomers observed MAMBO-9 without a lens. They also measured the mass of dust and gas in the galaxy, which is ten times the mass of all the stars in our galaxy. MAMBO-9 contains two parts (as shown in the image) that will eventually merge.

The light we are seeing has traveled approximately 13 billion years, which means what we are observing now has already happened in the past. Today, MAMBO-9 would probably have 100 times more stars than the Milky Way.

Read: What Is The Mass Of Entire Milky Way Galaxy?

The research team hopes to detect more such galaxies using ALMA and find how they evolved so early in the universe. The discovery will help scientists better understand our universe and ask even more logical questions about distant galaxies.

Written by
Varun Kumar

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