The Gamow Explorer is said to be a new gamma ray observatory to search for the first stars in the universe … as they explode

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Gamma rays aren’t just useful in turning humble scientists into green-skinned behemoths. They can also shed light on the deaths of some of the first stars in the universe. Specifically, they are part of the light caused by the death of the first stars in the universe. Today, a team of scientists led by Nicholas White of George Washington University, and formerly of NASA’s Goddard Space Flight Center, proposed an observation mission that would scan the sky for gamma-ray bursts (GRBs). and would use them to understand the early universe.

The mission is currently named Gamow Explorer in honor of George Gamow, one of the originators of the Big Bang Theory (scientific theory – not the popular American TV show). He will look at a period in the early universe called the era of reionization, where the hydrogen that made up the early universe went from neutral to ionized form. To do this, Gamow will focus on GRBs, the brightest explosions in the universe.

GRBs are so fantastic they justify their own UT video!

Mission designers came up with a three-step concept to fully capture and characterize GRBs as they occur. First, Gamow will frequently use the Lobster Eye X-ray Telescope (LEXT) to scan the sky for GRBs. The lobster eye optic has the added benefit of capturing a large part of the sky all at once. They were originally proposed in the 1970s by J. Roger P. Angel, now at the University of Arizona, the most recent technological advances have made the wide field of view inherent in lobster optics easier to achieve. technologically.

These technological advances are useful in another crucial area of ​​GRB analysis: speed. GRBs evolve rapidly, with even gusts of “long duration” lasting on average less than 30 seconds. While LEXT is good at initially detecting GRBs, it is not as good at collecting the detailed spectral data that scientists need. This is where the second Gamow instrument comes in – the Photo-z Infrared Telescope (PIRT) is designed to react to data from LEXT and look to any current GRBs.

Representation of the electromagnetic radiation of a GRB.
Credit – White et al.

Originally proposed in an article earlier this year, PIRT focuses on collecting the data needed to find GRBs that are unusually remote. To catch these fleeting explosions, Gamow is designed to direct the PIRT at any potential GRB candidate found by LEXT within 100 seconds of its discovery.

As PIRT captures the infrared wavelength data of the GRB afterglow, Gamow himself will be busy coordinating with a series of connected satellites in an attempt to turn as much observing power as possible to the GRB. Within 1000 seconds of discovering a new GRB, the mission is designed to notify other powerful telescopes. Those helping hands could include the soon-to-launch James Webb Space Telescope (JWST) and other ground-based telescopes that scan radio and visible light spectra.

A THESEUS SXI model that inspired the design of Gamow's LEXT module.
A THESEUS SXI model that inspired the design of Gamow’s LEXT module.
Credit – Feldman et al.

Part of the long response time for other systems on a GRB is believed to be due to Gamow’s location. Mission planners envision the telescope at Lagrange’s L2 point, the same location as JWST. But even at this distance, radio telescopes on Earth would be able to see some of the afterglow that was first discovered by the BeppoSAX observatory and confirmed by the Neil Gehrels Swift Observatory. Gamow would eclipse those two previous missions in terms of ability and sensitivity.

All this power is great, but what is it for? The GRBs Gamow is looking for are most likely caused by the fusion of extraordinarily dense objects – the exact kind of impacts that are believed to cause gravitational waves. Tying the electromagnetic output of such events to the gravitational waves they cause has so far been tricky. Gamow’s rapid response time is a simple solution to this problem, which has plagued the astronomical community since gravitational waves themselves were confirmed in 2017.

LEXT focal plane CAD model.
LEXT focal plane CAD model.
Credit – Feldman et al.

However, there is still a long way to go before Gamow or the like takes off. The mission team plans to deliver the concept as part of NASA’s MIDEX 2021 call, designed for ‘medium’ sized missions, such as those recently approved by the Decadal Survey. But the proposals are not guaranteed funding, although a similar idea, known to the Transient Astrophysics Observatory, has been circulating in the astronomical community for at least four years.

If accepted into the MIDEX program, Gamow plans to take off in 2028 and start collecting data on some of the galaxy’s brightest explosions soon after. Even then, however, he won’t turn any of his mission scientists into a superhero.

Learn more:
arXiv – The Gamow Explorer: an observatory on gamma-ray bursts to study the strongly redshifted universe and enable multi-messenger astrophysics
NASA – The Explorer of Gamow
arXiv – LEXT: a lobster eye lens for Gamow
NASA – Proposed NASA Mission Uses Lobster-Eye Optics to Locate Source of Cosmic Ripples

Main picture:
CAD image of the Gamow Explorer.
Credit – White et al.


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