Monday, January 23, 2023

3839 - RADIO ASTRONOMY - probing new distances?

 

     -  3839  -    RADIO  ASTRONOMY  -  probing new distances?     The detection of the special radio wavelength from the most distant galaxy means astronomers may be ready to investigate how the earliest stars form.  Astronomers have detected a radio signal from the most distant galaxy yet.


            ---------  3839  -   RADIO  ASTRONOMY  -  probing new distances?

            -    Radiowaves and astronomy almost seem like a contradiction.  But,  radiowaves are just the broad wavelength of the electromagnetic spectrum.  Light, Ultraviolet and gamma rays are at the other end,with the smallest wavelengths.

            -

            -    The signal was detected at a special and significant wavelength known as the "21-centimeter line" or the "hydrogen line," which is emitted by neutral hydrogen atoms.

            -

            -    The detection of the hydrogen line from such a galaxy so far away  and therefore so early in the universe  by the “Giant Metrewave Radio Telescope” in India could mean astronomers are ready to begin investigating the formation of the earliest stars and galaxies.

            -

            -    The signal from the star-forming galaxy SDSSJ0826+5630 was emitted when our 13.8 billion-year-old galaxy was just 4.9 billion years old. The signal allowed the astronomers to measure the galaxy's gas content and find that its mass is double that of the early galaxy's visible stars.

            -

            -    Galaxies emit electromagnetic radiation, or light, across a wide range of radio wavelengths, but thus far 21-cm-wavelength radio waves have only been seen from nearby and thus more recent galactic sources.

            -

            -    It's the equivalent to a look-back in time of 8.8 billion years.  A galaxy emits different kinds of radio signals. Until now, it's only been possible to capture this particular signal from a galaxy nearby, limiting our knowledge to those galaxies closer to Earth.

            -

            -    The difficulty in spotting these wavelengths from more distant galaxies is due to the fact that as electromagnetic radiation from early galaxies travels vast distances to Earth, the expansion of the universe stretches its wavelength and causes its energy to reduce. That means telescopes here on Earth need a natural boost to see long-wavelength, low-energy radio waves like the hydrogen line signal.

            -

            -    General relativity suggests that objects with mass warp spacetime similar to how a ball placed on a stretched rubber sheet would weigh it down in the center, and just like in that analogy, the greater the mass, the more extreme the curvature.

            -

            -    That means a tremendously massive object like a black hole or galaxy causes extreme curvature in spacetime just as a bowling ball would cause the extreme curvature of the rubber sheet in the analogy.

            -

            -    This curving of spacetime causes light to bend as well as it passes by objects of tremendous mass. A phenomenon known as gravitational lensing occurs when a foreground or lensing object of tremendous mass sits between an observer and a background source, causing the light from the background object to curve and take different paths through and around the lensing object. This can not only make a single object appear at multiple points in the sky, but it can also have the effect of magnifying this light.

            -

            -    In the case of SDSSJ0826+5630, the radio wave signal was magnified by another galaxy between the early galaxy acting as a lensing body.  This effectively results in the magnification of the signal by a factor of 30, allowing the telescope to pick it up.

            -

            -    This could in turn open up a new way of using long-wavelength radio telescopes to probe the evolution of stars and galaxies and how the early universe evolved into the cosmos we see around us in its current era.

            -

            January 23, 2022         RADIO  ASTRONOMY  -  probing new distances         3839                                                                                                                             

            ----------------------------------------------------------------------------------------

            -----  Comments appreciated and Pass it on to whomever is interested. ---

            ---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 

            --  email feedback, corrections, request for copies or Index of all reviews

            ---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

            --------------------- ---  Monday, January 23, 2023  ---------------------------

             

             

             

             

                     

             

-

 

 

 

 

           

 

 

No comments:

Post a Comment