Free Astronomy Magazine March-April 2024 ARABIC VERSION

29 ticular class of exploding stars, called type Ia (read “type one-A”) super- novae, and was recognized with the Nobel Prize in Physics in 2011. Now, 26 years after the initial dis- covery, the scientists working on the Dark Energy Survey (DES) have re- leased the results of an unprece- dented analysis using the same technique to further probe the mys- teries of dark energy and place the strongest constraints on the expan- sion history of the Universe ever ob- tained. In a presentation at the 243 rd meeting of the American Astronom- ical Society on 8 January 2024, and in a paper submitted to The Astro- physical Journal , astrophysicists re- port results that are consistent with the now-standard cosmological model of a Universe with an accel- erating expansion. Yet, the findings are not definitive enough to rule out a possibly more complex model. The DES is an international collabo- ration comprising more than 400 scientists from over 25 institutions, led by the US Department of En- ergy’s Fermi National Accelerator Laboratory. The DES employs the Dark Energy Camera (DECam), a 570-megapixel digital camera built by Fermilab and funded by the DOE Office of Science, with significant contributions by the NSF and the DES partners. It is mounted on the Víctor M. Blanco Telescope at CTIO in Chile. By taking data on 758 nights across six years, DES scientists mapped an area almost one-eighth of the entire sky. Among the observations of about two million distant galaxies, the DES team found several thousand super- novae, making this the largest, deep- est supernova sample ever obtained from a single telescope. DES researchers then used advanced machine-learning techniques to aid in supernova classification and sift the sample into a uniform high- quality dataset with 1499 likely type Ia supernovae, thereby tripling the number of observed supernova Ia beyond a redshift of 0.2 and quintu- pling the number beyond a redshift of 0.5. “It’s a really massive scale-up from 25 years ago when only 52 su- pernovae were used to infer dark energy,” said Tamara Davis, a pro- fessor at the University of Queens- land in Australia and co-convener of the DES Supernova Working Group. This large sample of supernovae, spanning a wide range of distances, can be used to trace out the history of cosmic expansion. For each super- nova, DES scientists combine its dis- tance with a measurement of its ﻤﻜــــﻦ ــــﻮن ﻣــــﻦ ﺧــــﻼل ﺗﺘﺒــــﻊ ﺗــــﺎر ﺦ ﺗﻮﺳــــﻊ اﻟ ــــــــــﺔ ﻣﻘﺎرــــــــــﺔ اﻟﺴــــــــــﺮﻋﺎت اﻟ اﺟﻌ ) اﻻﻧﺰ ﺎﺣــــــــــﺎت ا ﻤﺮاء ( ﻣﻊ اﻟﻤﺴﺎﻓﺎت اﻟﻤﺤﺪدة ﻟ ﻞ ﻣﺴﺘﻌﺮ أﻋﻈـــﻢ . ﺗﻈﻬـــﺮﻧﺘـــﺎﺋﺞ ﻣﺴـــﺢ اﻟﻄﺎﻗـــﺔ اﻟﻤﻈﻠﻤـــﺔ ـــﻮﻧﻲ، وﻫـــﻮ أن اﻟﺘﻮﺳــﻊ ﺘﺴـــﺎرع ﻣـــﻊ اﻟــﺰﻣﻦ اﻟ ﺗﻮﻗﻴﻊ اﻟﻄﺎﻗﺔ اﻟﻤﻈﻠﻤﺔ . ﻣﺜﺎل اﻛﺘﺸﻔﮫ ﻋﻠﻰ اﻟﻤﺴﺘﻌﺮاﻷﻋﻈﻢ اﻟﺬ ﻣﺴــﺢ اﻟﻄﺎﻗـــﺔ اﻟﻤﻈﻠﻤـــﺔ داﺧــﻞ اﻟﻤﺠـــﺎل اﻟـــﺬ ــــــﺔ ﻓــــــﻲ ــــــﮫ أﺣــــــﺪ أﺟﻬــــــﺰة اﻟﻜﺸــــــﻒ اﻟﻔﺮد ﻐﻄ ــــــﺎﻣ ا اﻟﻄﺎﻗــــــﺔ اﻟﻤﻈﻠﻤــــــﺔ . اﻧﻔﺠــــــﺮ اﻟﻤﺴــــــﺘﻌﺮ اﻷﻋﻈـﻢ ﻓــﻲﻣﺠــﺮة ــﺔ ذات اﻧﺰ ــﺎح أ ﻤــﺮ ﺣﻠﺰوﻧ = 0.04528 وﻫـــﻮ ﻣـــﺎ ﺘﻮاﻓـــﻖ ﻣـــﻊ زﻣـــﻦﺳـــﻔﺮ ــــــــــــﺎﻟﻎﺣــــــــــــﻮاﻟﻲ اﻟﻀــــــــــــﻮء اﻟ 0.6 ــــــــــــﺎرﺳــــــــــــﻨﺔ ﻣﻠ . ـــــــﻮازاراﻟﻤﻮﺟـــــــﻮد ﻋﻠـــــــﻰ و ﺎﻟﻤﻘﺎر ـــــــﺔ، ﻓـــــــﺈن اﻟ ـــﮫ اﻧﺰ ـــﺎح أ ﻤـــﺮﻗـــﺪرﻩ ﻟﺪ اﻟ ﻤـــ 3.979 وزﻣـــﻦ ﺳﻔﺮﺿﻮﺋﻲﻗﺪرﻩ 11.5 ﻣﻠ ﺎرﺳﻨﺔ . - ﻣﺎﺭﺱ ﺃﺑﺮﻳﻞ 2 0 2 4 29 اﻷول -A(" وﺣﺼـﻠﺖ ﻋ ـﲆ ﺟــﺎﺋﺰة ﻧﻮﺑــﻞ ﰲ اﻟﻔﻴﺰﻳﺎء ﰲ ﻋﺎم 2011 . اﻵن وﺑﻌـﺪ ﻣـﺮور 26 ﺎً ﻋﺎﻣ ﻋـﲆ اﻻﻛﺘﺸـﺎف اﻷوﱄ أﺻـﺪر اﻟﻌﻠﻤـﺎء اﻟﻌﺎﻣﻠﻮن ﰲ ﺑﺮﻧﺎﻣﺞ ﻣﺴﺢ اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤـﺔ ﻧﺘﺎﺋﺞ ﺗﺤﻠﻴﻞ ﻏ ﻣﺴﺒﻮق ﺑﺎﺳـﺘﺨﺪام ﻧﻔـﺲ اﻟﺘﻘﻨﻴﺔ ﻮاﺻـﻠﺔ اﺳﺘﻜﺸـﺎف أﴎار اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤﺔ ووﺿـﻊ أﻗـﻮى اﻟﻘﻴـﻮد ﻋـﲆ ﺗﻮﺳـﻊ ﺗﺎرﻳﺦ اﻟﻜﻮن اﻟﺘﻲ ﺗﻢ اﻟﺤﺼﻮل ﻋﻠﻴﻬﺎ ﻣﻘﺎرﻧﺔ وﻗﺖ ﻣﴣ ــــ ﻮﻗﺖ ﻣﴣ . ﺑـﺄي وﻗ ـﺖ ﻣ ـ .ﴣـ ﰲ ﻋــﺮض ﺗﻘ ـﺪﻳﻤﻲ ﰲ اﻻﺟﺘﻤﺎع 243 ﻟﻠﺠﻤﻌﻴﺔ اﻟﻔﻠﻜﻴﺔ اﻷﻣﺮﻳﻜﻴﺔ ﰲ 8 ﻳﻨﺎﻳﺮ 2024 وﰲ ورﻗـﺔ ﺑﺤﺜﻴـﺔ ﻣﻘﺪﻣـﺔ إﱃ ﻣﺠﻠﺔ اﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴﺔ ذﻛﺮ ﻋﻠﻤـﺎء اﻟﻔﻴﺰﻳـﺎء اﻟﻔﻠﻜﻴﺔ ﻧﺘﺎﺋﺞ ﺗﺘﻮاﻓﻖ ﻣﻊ اﻟﻨﻤـﻮذج اﻟﻜـﻮﻧﻲ اﻟﻘﻴﺎﳼ اﻵن ﻟﻠﻜﻮن ﻣـﻊ اﻟﺘﻮﺳـﻊ ا ﺘﺴـﺎرع وﻣﻊ ذﻟﻚ ﻓﺈن اﻟﻨﺘﺎﺋﺞ ﻟﻴﺴﺖ ﻧﻬﺎﺋﻴﺔ ﺑﻤﺎ ﻳﻜﻔﻲ ﻻﺳﺘﺒﻌﺎد ﻧﻤـﻮذج أﻛﺜـﺮ ﺗﻌﻘﻴـﺪ إن. اً ﺑﺮﻧـﺎﻣﺞ ﻣﺴﺢ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ﻋﺒﺎرة ﻋﻦ ﺗﻌـﺎون دوﱄ ﻳﻀﻢ أﻛﺜﺮ ﻣﻦ 400 ﻋﺎﻟﻢ ﻣـﻦ أﻛﺜـﺮ ﻣـﻦ 25 ﻣﺆﺳﺴـﺔ ﺑﻘﻴـﺎدة ﻣﺨﺘـﱪ ﻓ ﻣـﻲ اﻟـﻮﻃﻨﻲ ﻟﻠﺘﺴﺎرع اﻟﺘﺎﺑﻊ ﻟـﻮزارة اﻟﻄﺎﻗـﺔ اﻷﻣﺮﻳﻜﻴـﺔ . وﻫــﺬا اﻟﱪﻧـﺎﻣﺞ ﻳﺴـﺘﺨﺪم ﻛـﺎﻣ ا اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤﺔ ) دي ﻛﺎم ( وﻫﻲ ﻛﺎﻣ ا رﻗﻤﻴﺔ ﺑﺪﻗـﺔ 570 ﻣﻴﺠﺎﺑﻜﺴـﻞ ﺗ ـﻢ ﺗﺼ ـﻨﻴﻌﻬﺎ ﺑﻮاﺳ ـﻄﺔ ﻣﺨﺘﱪ ﻓ ﻣﻴﻼب وﺑﺘﻤﻮﻳﻞ ﻣﻦ ﻣ ﻜﺘﺐ اﻟﻌﻠـﻮم اﻟﺘﺎﺑﻊ ﻟﻮزارة اﻟﻄﺎﻗﺔ ﻣﻊ ﻣﺴـﺎﻫﻤﺎت ﻛﺒـ ة ﻣـﻦ ﻣﺆﺳﺴـﺔ اﻟﻌﻠـﻮم اﻟﻮﻃﻨﻴـﺔ اﻷﻣﺮﻳﻜﻴـﺔ اﻟـو ﴩﻛﺎء ﰲ اﻟﱪﻧﺎﻣﺞ . ﺗـﻢ ﺗﺜﺒﻴـﺖ اﻟﻜـﺎﻣ ا ﻋﲆ ﺗﻠﺴﻜﻮب ﻓﻴﻜﺘﻮر ﺑﻼﻧﻜﻮ ﰲ ﺗﺸﻴﲇ وﻣـﻦ ﺧﻼل ﺟﻤﻊ ﺑﻴﺎﻧﺎت ﻣﻦ 758 ﻟﻴﻠﺔ ﻋـﲆ ﻣـﺪار ﺳﺖ ﺳـﻨﻮات رﺳـﻢ ﻋﻠﻤـﺎء ﺑﺮﻧـﺎﻣﺞ ﻣﺴـﺢ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ﺧﺮﻳﻄﺔ ﻨﻄﻘﺔ ﺗﻌﺎدل ﺗﻘﺮﻳﺒ ﺎً ﺛﻤﻦ اﻟﺴﻤﺎء ﺑﺄﻛﻤﻠ .ﻬﺎ إن ﻣﻦ ﺑ ﻋﻤﻠﻴﺎت اﻟﺮﺻـﺪ ﻟﺤـﻮاﱄ ﻣﻠﻴـﻮﻧﻲ ﻣﺠﺮة ﺑﻌﻴﺪة وﺟﺪ ﻓﺮﻳﻖ اﻟﱪﻧـﺎﻣﺞ ﻋـﺪة آﻻف ﻣﻦ ا ﺴﺘﻌﺮات اﻟﻌﻈﻤﻰ ﻣﻤـﺎ ﻳﺠﻌﻠﻬـﺎ أﻛـﱪ وأﻋﻤﻖ ﻋﻴﻨـﺔ ﻣـﻦ ا ﺴـﺘﻌﺮات ا ﻟﻌﻈﻤـﻰ ﺗـﻢ اﻟﺤﺼﻮل ﻋﻠﻴﻬﺎ ﻣﻦ ﺗﻠﺴﻜﻮب . واﺣﺪ اﺳﺘﺨﺪم ــــــ ﺑﺎﺣﺜﻮ ﺑﺮﻧﺎﻣﺞ ﻣﺴﺢ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ﺑﻌﺪ ذﻟﻚ ﺗﻘﻨﻴﺎت اﻟـﺘﻌﻠﻢ اﻵﱄ ا ﺘﻘﺪﻣـﺔ ﻟﻠﻤﺴـﺎﻋﺪة ﰲ ﺗﺼﻨﻴﻒ ا ﺴﺘﻌﺮات اﻷﻋﻈﻢ وﻏﺮﺑﻠﺔ اﻟﻌﻴﻨـﺔ ﰲ ﻣﺠﻤﻮﻋـﺔ ﺑﻴﺎﻧـﺎت ﻣﻮﺣـﺪة ﻋﺎﻟﻴـﺔ اﻟﺠـﻮدة ﺗﺤﺘﻮي ﻋﲆ 1499 اً ﻣﺴﺘﻌﺮ أﻋﻈﻢ ﻣﻦ اﻟﻨـﻮع Ia ، وﺑﺎﻟﺘــﺎﱄ ﻣﻀــﺎﻋﻔﺔ ﻋــﺪد ا ﺴــﺘﻌﺮات اﻟﻌﻈﻤﻰ Ia ا ﺮﺻﻮدة ﺛﻼث ﻣﺮات ﺑﻌﺪ اﻧﺰﻳﺎح أﺣﻤﺮ ﻗﺪره 0,2 وﻣﻀﺎﻋﻔﺔ اﻟﻌﺪد ﺧﻤﺲ ﻣﺮات اﻧﺰﻳﺎح أﺣﻤﺮ ﻗﺪره 0,5 . ﻗﺎﻟـﺖ ﺗﻤـﺎرا دﻳﻔـﻴﺲ اﻷﺳـﺘﺎذة ﰲ ﺟﺎﻣﻌـﺔ ﻛﻮﻳﻨﺰﻻﻧﺪ ﰲ أﺳـﱰاﻟﻴﺎ، وا ﺆﺳﺴـﺔ ا ﺸـﺎرﻛﺔ ﺠﻤﻮﻋ ـﺔ ﻋﻤــﻞ ﻣﺴ ـﺢ اﻟﻄﺎﻗــﺔ ا ﻈﻠﻤــﺔ ) : " ( ﺳﻮﺑﺮﻧﻮﻓﺎ إﻧﻪ ﺗﻮﺳﻊ ﻫﺎﺋـﻞ ﺣﻘـﺎً ﻋﻤـﺎ ﻛﺎن ﻋﻠﻴﻪ ﻗﺒﻞ 25 ﺎً ﻋﺎﻣ ﻋﻨﺪﻣﺎ ﺗـﻢ اﺳـﺘﺨﺪام 52 اً ﻣﺴﺘﻌﺮ أﻋﻈﻢ ﻓﻘـﻂ ﻻﺳـﺘﻨﺘﺎج اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤﺔ ." ﻳﻤﻜﻦ اﺳـﺘﺨﺪام ﻫـﺬه اﻟﻌﻴﻨـﺔ اﻟﻜﺒـ ة ﻣـﻦ ا ﺴﺘﻌﺮات اﻟﻌﻈﻤﻰ واﻟﺘﻲ ﺗﻤﺘـﺪ ﻋـﲆ ﻧﻄـﺎق واﺳﻊ ﻣﻦ ا ﺴﺎﻓﺎت ﻟﺘﺘﺒـﻊ ﺗـﺎرﻳﺦ اﻟﺘﻮﺳـﻊ اﻟﻜﻮﻧﻲ . ﺑﺎﻟﻨﺴﺒﺔ ﻟﻜﻞ ﻣﺴﺘﻌﺮ أﻋﻈـﻢ ﻳﺠﻤـﻊ ﻋﻠﻤﺎء ﺑﺮﻧﺎﻣﺞ ﻣﺴﺢ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ا ﺴﺎﻓﺔ