Free Astronomy Magazine March-April 2024 ARABIC VERSION

redshift — how quickly it is moving away from Earth as a result of the expansion of the Universe. To- gether, these two factors can lend insight into whether the Universe’s dark energy density has remained constant or changed over time. “As the Universe expands, the mat- ter density goes down,” said DES di- rector and spokesperson Rich Kron, who is a Fermilab and University of Chicago scientist. “But if the dark energy density is a constant, that means the total proportion of dark energy must be increasing as the volume increases.” The standard cosmological model is known as Λ CDM, or ‘Lambda cold dark matter’. This mathematical model describes how the Universe evolves using just a few features such as the density of matter, the type of matter and the behavior of dark energy. While Λ CDM assumes the density of dark energy in the Universe is constant over cosmic time and doesn’t dilute as the Uni- verse expands, the DES Supernova Survey results hint that this may not be true. Results were obtained by combining the DES data with complementary data from the European Space Agency’s Planck telescope. An in- triguing outcome of this survey is that it is the first time that enough distant supernovae have been meas- ured to make a highly detailed measurement of the decelerating phase of the Universe, and to see where the Universe transitions from decelerating to accelerating. And while the results are consistent with a constant density of dark energy in the Universe, they also hint that dark energy might possibly be vary- ing. “There are tantalizing hints that dark energy changes with time,” said Davis, “We find that the sim- plest model of dark energy — Λ CDM — is not the best fit. It’s not so far off that we’ve ruled it out, but in the quest to understand what is acceler- ating the expansion of the Universe this is an intriguing new piece of the puzzle. A more complex explana- tion might be needed.” The innovative tech- niques that the DES has pioneered will shape and further drive future astrophysical analyses. Projects like the upcom- ing Legacy Survey of Space and Time, to be conducted by Vera C. Rubin Observatory, which is operated jointly by NSF’s NOIRLab and DOE’s SLAC National Ac- celerator Laboratory, as well as NASA’s Nancy Grace Roman Space Tel- escope, will pick up where the DES left off. “We’re pioneering tech- niques that will be di- rectly beneficial for the next generation of supernova sur- veys,” said Kron. “This result clearly shows the value of astronomical survey projects that continue to yield excellent science well after data collection has ended,” says Nigel Sharp, a pro- gram director in NSF’s Astronomical Sciences Division. “We need as many diverse approaches as we can get in order to understand what dark en- ergy is, and what it isn’t. This is an important route to that under- standing.” Alistair Walker, DECam Instrument Scientist at NOIRLab, adds, “Multi- ple elements came together to per- mit this important advance in our understanding of dark energy — the pristine skies of Chile, the large Blanco Telescope equipped with the superbly-made DECam, inten- sive data calibration efforts that achieved unprecedented levels of measurement accuracy and a decade of analysis effort by a very talented group of scientists.”     30 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ ﺑﻴﻨﻪ وﺑ ﻗﻴﺎس اﻧﺰﻳﺎﺣﻪ ﻧﺤﻮ اﻷﺣﻤﺮ، أي ﻣﺪىﴎﻋﺔ اﺑﺘ ﻌﺎده ﻋــﻦ اﻷرض ﻧﺘﻴﺠــﺔ ﻟﺘﻮﺳــﻊ اﻟﻜﻮن ﻳﻤﻜﻦ ﻟﻬﺬﻳﻦ اﻟﻌـﺎﻣﻠ ﺎً ﻣﻌ أن ﻳﻘﺪﻣﺎ ﻧﻈﺮة ﺛﺎﻗﺒﺔ ﺣﻮل ﻣـﺎ إذا ﻛﺎﻧـﺖ ﻛﺜﺎﻓـﺔ اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤﺔ ﰲ اﻟﻜﻮن ﻇﻠﺖ ﺛﺎﺑﺘﺔ أم ﺗﻐ ت ﻣﻊ ﻣﺮور اﻟﻮﻗﺖ . ﻗﺎل رﻳﺘﺶ ﻛﺮون ﻣﺪﻳﺮ ﺑﺮﻧﺎﻣﺞ ﻣﺴـــﺢ اﻟﻄﺎﻗـــﺔ ا ﻈﻠﻤـــﺔ وا ﺘﺤــﺪث اﻟﺮﺳــﻤﻲ ﺑﺎﺳــﻤﻪ وﻫﻮ ﻋﺎﻟﻢ ﰲ ﻣﺨﺘﱪ ﻓ ﻣـﻴﻼب وﺟﺎﻣﻌﺔ ﺷﻴﻜﺎﻏﻮ " : ﻣﻊ ﺗﻮﺳﻊ اﻟﻜﻮن، ﺗﻨﺨﻔﺾ ﻛﺜﺎﻓﺔ ا ـ ﺎدة وﻟﻜﻦ إذا ﻛﺎﻧﺖ ﻛﺜﺎﻓﺔ اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤﺔ ﺛﺎﺑﺘﺔ، ﻓﻬـﺬا ﻳﻌﻨـﻲ أن اﻟﻨﺴــﺒﺔ اﻹﺟﻤﺎﻟﻴــﺔ ﻟﻠﻄﺎﻗــﺔ ا ﻈﻠ ﻤﺔ ﻳﺠـﺐ أن ﺗﺘﺰاﻳـﺪ ﻣـﻊ زﻳﺎدة اﻟﺤﺠﻢ " . ﻳُﻌﺮف اﻟﻨﻤﻮذج اﻟﻜﻮﻧﻲ اﻟﻘﻴﺎﳼ ﺑﺎﺳﻢ Λ CDM أو " ﻻﻣــﺪا ا ــﺎدة ا ﻈﻠﻤــﺔ اﻷﻧﺰ ــﺎح ــﺔ ﻟﻠ اﻷ ﻤــﺮﻫــﻮ اﻟﻤﺼـﻄﻠﺢ اﻟﻤﺴــﺘﺨﺪم ﻟﻮﺻـﻒ ﺗﻤــﺪد اﻷﻃــﻮال اﻟﻤﻮﺟ ــﻮن ﻀــﻮء ﻣــﻦ ﺟﺴـﻢ ﻣــﺎ ﻧﺘﻴﺠــﺔ ﻟﺘﻮﺳــﻊ اﻟ ﻠﻤﺎ زادت ﻣﺴﺎﻓﺔ اﻟ ـ ﺠﺴﻢ زاد اﻻﻧﺰ ﺎح ﻧﺤﻮ اﻷ ﻤﺮ . ﺘﻢ ﺗﺤﺪ ﺪ اﻟﺘﺎر ﺦ اﻟﺘﻔﺼ ﻠﻲ ﻟﺘﻮﺳﻊ اﻟ ﻮن ﻣﻦ ﺧﻼل ﻋﻼﻗـﺔ دﻗ ﻘـﺔ ﺑـ اﻟﻤﺴﺎﻓﺎت إﻟﻰ اﻟﻤﺠﺮات - أو اﻟﻤﺴﺘﻌﺮات اﻷﻋﻈﻢ - واﻧﺰ ﺎﺣﺎﺗﻬﺎ ﻧﺤﻮ اﻷ ﻤﺮ . اﻟﺒﺎردة . ﻳﺼﻒ ﻫﺬا اﻟﻨﻤﻮذج اﻟﺮﻳﺎﴈ ﻛﻴﻔﻴـﺔ ﺗﻄﻮر اﻟﻜﻮن ﺑﺎﺳﺘﺨﺪام ﺑﻌ ﻂ ﺾ ا ﻴﺰات ﻓﻘـ واﻟﺘﻲ ﺗﺸﻤﻞ ﻛﺜﺎﻓﺔ ا ﺎدة وﻧﻮع ا ﺎدة وﺳﻠﻮك اﻟﻄﺎﻗﺔ ا ﻈﻠﻤـﺔ ﺑﻴﻨﻤـﺎ ﻳﻔـﱰض Λ CDM أن ﻛﺜﺎﻓﺔ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ﰲ اﻟﻜـﻮن ﺛﺎﺑﺘـﺔ ﻋـﲆ ﻣﺪار اﻟﺰﻣﻦ اﻟﻜﻮﻧﻲ وﻻ ﺗﻀـﻌﻒ ﻣـﻊ ﺗﻮﺳـﻊ اﻟﻜﻮن . ﺗﺸ ﻧﺘﺎﺋﺞ ﺑﺮﻧﺎﻣﺞ ﻣﺴﺢ اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤـﺔ ) ( ﺳﻮﺑﺮﻧﻮﻓﺎ إﱃ أن ﻫﺬا ﻗﺪ ﻻ ﻳﻜﻮن ﺻﺤﻴﺤ .ﺎً ﺗﻢ اﻟﺤﺼﻮل ﻋﲆ اﻟﻨﺘﺎﺋﺞ ﻣﻦ ﺧﻼل اﻟﺠﻤﻊ ﺑ ﺑﻴﺎﻧ ـﺎت ﺑﺮﻧـﺎﻣﺞ ﻣﺴـﺢ اﻟﻄﺎﻗــﺔ ا ﻈﻠﻤ ـﺔ واﻟﺒﻴﺎﻧﺎت اﻟﺘﻜﻤﻴﻠﻴﺔ ﻣﻦ ﺗﻠﺴﻜﻮب ﺑﻼﻧﻚ اﻟﺘﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑﻴﺔ . إن إﺣﺪى اﻟﻨﺘﺎﺋﺞ ا ﺜ ة ﻟﻼﻫﺘﻤﺎم ﻟﻬﺬا ا ﺴﺢ اﻟﻌﻤﲇ ﻫﻲ أﻧﻬﺎ ا ـﺮة اﻷوﱃ اﻟﺘـﻲ ﻳـﺘﻢ ﻓﻴﻬـﺎ ﻗﻴﺎس ﻣﺎ ﻳﻜﻔـﻲ ﻣـﻦ ا ﺴـﺘﻌﺮات اﻟﻌﻈﻤـﻰ اﻟﺒﻌﻴﺪة ﻹﺟﺮاء ﻗﻴﺎس ﻣﻔﺼﻞ ﻟﻠﻐﺎﻳـﺔ ﺮﺣﻠـﺔ ﺗﺒﺎﻃﺆ اﻟﻜﻮن ورؤﻳﺔ أﻳﻦ ﻳﻨﺘ ﻘـﻞ اﻟﻜـﻮن ﻣـﻦ اﻟﺘﺒﺎﻃﺆ إﱃ اﻟﺘﺴﺎرع وﰲ ﺣ أن اﻟﻨﺘﺎﺋﺞ ﺗﺘﻔﻖ ﻣﻊ ﻛﺜﺎﻓ ﺔ ﺛﺎﺑﺘﺔ ﻟﻠﻄﺎﻗـﺔ ا ﻈﻠﻤـﺔ ﰲ اﻟﻜـﻮن ﻓﺈﻧﻬﺎ ﺗﺸ أﻳﻀ ﺎُ إﱃ أن اﻟﻄ ﺎ ﻗﺔ ا ﻈﻠﻤﺔ رﺑﻤـﺎ ﺗﻜــﻮن ﻣﺘﻔﺎوﺗــﺔ . ﻗــﺎل دﻳﻔــﻴﺲ " : ﻫﻨــﺎك ﺗﻠﻤﻴﺤﺎت ﻣﺤ ة ﺗﺸ إﱃ أن اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ﺗﺘﻐ ﻣﻊ ﻣﺮور اﻟﻮﻗﺖ ." ـــــ ﺗﺘﻐ ﻣﻊ ﻣﺮور اﻟﻮﻗﺖ "." ﻟﻘﺪ وﺟﺪﻧﺎ أن أﺑﺴﻂ ﻧﻤﻮذج ﻟﻠﻄﺎﻗﺔ ا ﻈﻠﻤﺔ - Λ CDM - ﻟﻴﺲ ﻫﻮ اﻷﻓﻀﻞ . ﻟﻢ ﻧﺴﺘﺒﻌﺪ ذﻟﻚ ﻛﺜ ًا، وﻟﻜﻦ ﰲ ﺳﻌﻴﻨﺎ ﻟﻔ ﻬﻢ ﻣﺎ ﻳﴪع ﺗﻮﺳﻊ اﻟﻜﻮن ﻳﻌﺪ ﻫـﺬا ﺟـﺰء اً اً ﻣﺜ اً ﺟﺪﻳﺪ ﻟﻼﻫﺘﻤﺎم ﻣﻦ اﻟﻠﻐﺰ . ﻗﺪ ﺗﻜﻮن ﻫﻨﺎك ﺣﺎﺟﺔ إﱃ ﺗﻔﺴ أﻛﺜﺮ ﺗ ﻔﺼﻴﻼً ﻟﻬﺬا اﻷﻣﺮ ". إن اﻟﺘﻘﻨﻴﺎت ا ﺒﺘﻜﺮة اﻟﺘـﻲ اﺑﺘﻜﺮﻫـﺎ ﺑﺮﻧـﺎﻣﺞ ﻣﺴـﺢ اﻟﻄﺎﻗــﺔ ا ﻈﻠﻤـﺔ ﺳﺘﺸـﻜﻞ وﺗ ـﺪﻓﻊ اﻟﺘﺤﻠﻴﻼت اﻟﻔﻴﺰﻳﺎﺋﻴﺔ اﻟﻔﻠﻜﻴﺔ ا ﺴـﺘﻘﺒﻠﻴﺔ إﱃ اﻷﻣﺎم . إن ﻣﺸﺎرﻳﻊ ﻣﺜﻞ ا ﺴ ﺢ اﻟﱰاﺛﻲ اﻟﻘﺎدم ﻟﻠﻤﻜﺎن واﻟﺰﻣﺎن اﻟﺬي ﺳﻴﺠﺮﻳﻪ ﻣﺮﺻﺪ ﻓ ا ﳼ روﺑ واﻟﺬي ﻳﺘﻢ ﺗﺸﻐﻴﻠﻪ ﺑﺸﻜﻞ ﻣﺸـﱰك ﻣـﻦ ﻗﺒـﻞ ﻣﺨﺘ ـﱪ ﻧ ـﻮﻳﺮﻻب اﻟﺘـﺎﺑﻊ ﺆﺳﺴـﺔ اﻟﻌﻠ ـﻮم اﻟﻮﻃﻨﻴﺔ وﻣﺨﺘـﱪ ا ــﴪع اﻟـﻮﻃﻨﻲ SLAC اﻟﺘﺎﺑ ﻊ ﻟﻮزارة اﻟﻄﺎﻗﺔ اﻷﻣﺮﻳﻜﻴﺔ ﺑﺎﻹﺿـﺎﻓﺔ إﱃ ﺗﻠﺴﻜﻮب ﻧﺎﻧ ـ ﴘ ﺟﺮﻳﺲ روﻣـﺎن اﻟﻔﻀـﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳﺎ . ﻗﺎل ﻛـﺮون ﺳ: ﻨﺴـﺘﺄﻧﻒ ﻣـﻦ ﺣﻴـﺚ ﺗﻮﻗـﻒ ﺑﺮﻧﺎﻣﺞ ﻣﺴﺢ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ﻓ ﻨﺤﻦ راﺋـﺪون ﰲ اﻟﺘﻘﻨﻴﺎت ا ﺘﻘﺪﻣﺔ اﻟﺘـﻲ ﺳـﺘﻜﻮن ﻣﻔﻴـﺪة ﺑﺸﻜﻞ ﻣﺒﺎﴍ ﻟﻠﺠﻴﻞ اﻟﻘﺎدم ﻣـﻦ ﻣﺴـﻮﺣﺎت ﻤﻞـاﻟ ا ﺴﺘﻌﺮات اﻟﻌﻈﻤﻰ ." ﻳﻘﻮل ﻧﺎﻳﺠﻞ ﺷـﺎرب، ﻣﺪﻳﺮ اﻟﱪﻧـﺎﻣﺞ ﰲ ﻗﺴـﻢ اﻟﻌﻠـﻮم اﻟﻔﻠﻜﻴـﺔ ﰲ ﻣﺆﺳﺴـﺔ اﻟﻌﻠـﻮم اﻟﻮﻃﻨﻴـﺔ : " ﺗﻈﻬـﺮ ﻫـﺬه اﻟﻨﺘﻴﺠـﺔ ﺑﻮﺿـﻮح ﻗﻴﻤــﺔ ﻣﺸـﺎرﻳﻊ ا ﺴــﺢ اﻟﻔﻠﻜﻲ اﻟﺘﻲ ﺗﺴﺘﻤﺮ ﰲ إﻧﺘﺎج ﻋﻠﻮم ﻏﺰﻳﺮة ﺑﻌﺪ ﻓﱰة ﻃﻮﻳﻠﺔ ﻣﻦ اﻧﺘﻬﺎء ﺟﻤﻊ اﻟﺒﻴﺎﻧﺎت ﻧﺤـﻦ و ﺑﺤﺎﺟﺔ إﱃ اﻟﻌﺪﻳﺪ ﻣﻦ اﻷﺳﺎﻟﻴﺐ ا ﺘﻨﻮﻋﺔ اﻟﺘـﻲ ﻳﻤﻜﻨﻨﺎ اﻟﺤﺼﻮل ﻋﻠﻴﻬﺎ ﻣﻦ أﺟﻞ ﻓﻬﻢ ﻃﺒﻴﻌـﺔ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ وﻫ ﺬا ﻃﺮﻳﻖ ﻣﻬﻢ ﻟ ﺘﺤﻘﻴﻖ ﻫﺬا اﻟﻔﻬﻢ ". ﻳﻀﻴﻒ أﻟﻴﺴﱰ ووﻛﺮ ﻋﺎﻟﻢ ) ﻛﺎﻣ ا دي ﻛﺎم ( ﰲ ا ﺨﺘﱪ اﻟﻮﻃﻨﻲ ﻷﺑﺤﺎث ﻋﻠﻢ اﻟﻔﻠﻚ اﻟﺒﴫي واﻷﺷـﻌﺔ ﺗﺤـﺖ اﻟﺤﻤــﺮاء ﻧـﻮﻳﺮﻻب اﻟﺘــﺎﺑﻊ ﺆﺳﺴﺔ اﻟﻌﻠـﻮم اﻟﻮﻃﻨﻴـﺔ : " ﻟﻘـﺪ اﺟﺘﻤﻌـﺖ ﻋﻨﺎﴏﻣﺘﻌﺪدة ﻟﻠﺴﻤﺎح ﺑﻬﺬا اﻟﺘﻘﺪم ا ﻬـﻢ ﰲ ﻓﻬﻤﻨﺎ ﻟﻠﻄ ﺎﻗﺔ ا ﻈﻠﻤﺔ إﺿﺎﻓﺔ إﱃ ﺳﻤﺎء ﺗﺸﻴﲇ اﻟﻨ ﻘﻴﺔ واﻟﺼﺎﻓﻴﺔ وﺗﻠ ﺴـﻜﻮب ﺑﻼﻧﻜـﻮ اﻟﻜﺒـ ا ﺠﻬﺰ ﺑﻜﺎﻣ ا ) دي ﻛـﺎم ( اﻟﺮاﺋﻌـﺔ اﻟﺼـﻨﻊ وﺟﻬﻮد ﻣﻌﺎﻳﺮة اﻟﺒﻴﺎﻧﺎت ا ﻜﺜﻔﺔ اﻟﺘﻲ ﺣﻘﻘﺖ ﻣﺴﺘﻮﻳﺎت ﻏ ﻣﺴـﺒﻮﻗﺔ ﻣـﻦ دﻗـﺔ اﻟﻘﻴـﺎس واﻟﻌﺪﻳﺪ ﻣﻦ اﻟﺴﻨﻮات ﻣﻦ اﻟﺠﻬـﻮد اﻟﺘﺤﻠﻴﻠﻴـﺔ اﻟﺘﻲ ﻗﺎم ﺑﻬﺎ ﻣﺠﻤﻮﻋﺔ ﻣﻮﻫﻮﺑﺔ ﻟﻠﻐﺎﻳـﺔ ﻣـﻦ اﻟﻌﻠﻤﺎء ا ﻤﻴﺰﻳﻦ ﰲ ﻫﺬا ا ﺠﺎل . . - ﻣﺎﺭﺱ ﺃﺑﺮﻳﻞ 2 0 2 4