- 3495 - QUASARS - blackholes on steroids? “Quasars” shine so brightly that they eclipse the galaxies in which these objects are embedded. Quasars are distant objects powered by blackholes typically a billion times as massive as our sun. They emit energies that can climb to trillions of electron volts, exceeding the total output of all the stars in a typical galaxy.
--------------------- 3495 - QUASARS - blackholes on steroids?
- Scientists hope to learn what part quasars play in galaxy evolution during the early times in our Universe expansion. The James Web Telescope hopes to learn more by perching in deep space using its extreme sensitivity to low levels of light and high resolution to make the most detailed set of observations yet possible of these elusive objects.
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- Once Webb finishes its commissioning period this summer, 2022, the telescope will be tasked with several quasar programs. Webb will look at six of the most distant and luminous quasars to situate these objects in the timeline of galactic evolution. Quasars will also be used to look at gas distribution between galaxies.
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- Scientists are interested in learning more about a period known as the epoch of “deionization“. This epoch happened 13 billion years ago, or less than a billion years after the universe was formed. Galaxies of the era were largely opaque to energetic light and those objects are thus difficult to observe.
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- Going out in distance is going back in time. How amazing is that?
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- Quasars are used as background light sources to study the gas between us and the quasar. The inter galactic gas absorbs the quasar's light at specific wavelengths. Through a technique called imaging spectroscopy, astronomers will look for absorption lines in the intervening gas.
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- Webb's ability to observe in infrared light will also be a boon for observations of this period. It will especially be useful because the most distant quasars' light were severely stretched by expansion of space. This phenomenon, known as “cosmological redshift“, moves light waves to the red or infrared area of the spectrum, where Webb is optimized to make observations. Expanding space stretches light’s wavelength into longer wavelengths, lower frequencies.
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- It is hoped that Webb will see enough light from the quasars to look for elements heavier than hydrogen or helium, elements that are called "metals" by astronomers. These elements were formed in the first stars and the first galaxies and expelled by outflows.
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- Outflows will be studied to better understand how gas accreted by a supermassive blackhole embedded in a galaxy pushes and heats up surrounding gas. The outflows can become so strong that they create chaos in the host galaxy and greatly affect the galaxy's evolution.
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- The supermassive blackholes in active galaxies can produce narrow particle jets and wider streams of gas known as ultra-fast outflows, which are powerful enough to regulate both star formation in the wider galaxy and the growth of the blackhole. .
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- That gas removed from a galaxy will slow the rate of star formation, since stars depend on gas to form and grow. In some cases, outflows will rob the galaxy of so much gas that star formation will cease completely.
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- Scientists also think that outflows are the main mechanism by which gas, dust and elements are redistributed over large distances within the galaxy, or can even be expelled into the space between galaxies, the intergalactic medium.
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- Going back in time to learn more about how we got to this time.
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March 6, 2022 QUASARS - blackholes on steroids? 3495
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