Isifundo Somkhathi Wase-Early: REACH Ukulinga ukuthola ulayini we-21-cm ovela ku-Cosmic Hydrogen 

Ukubuka kwe-26 cm radio amasignali, akhiwe ngenxa yokuguqulwa kwe-hyperfine ye-cosmic hydrogen inikeza elinye ithuluzi ocwaningweni lwangaphambi kwesikhathi indawo yonke. Ngokuqondene nenkathi yokungathathi hlangothi yosana indawo yonke lapho kungekho kukhanya okukhishiwe, imigqa engu-26 cm mhlawumbe iyifasitela kuphela. Nokho, lezi zashintsha radio amasignali akhishwa yi-cosmic hydrogen ekuqaleni indawo yonke zibuthakathaka kakhulu futhi azikatholakali kuze kube manje. Ngo-2018, ukuhlolwa kwe-EDGE kubike ukutholwa kwamasiginali angama-26 cm kodwa okutholakele akukwazanga ukuqinisekiswa ngokuzimela. Inkinga enkulu bekuwukuhleleka kwethuluzi kanye nokungcoliswa nezinye izimpawu ezivela esibhakabhakeni. I-REACH Experiment iwukusebenzisa indlela ehlukile yokunqoba ibhodlela. Kwethenjwa ukuthi leli qembu locwaningo lizokwazi ngokuthembekile ukuthola lezi zimpawu ezingaqondakali esikhathini esizayo esiseduze. Uma kuphumelele, i-REACH Experiment ingase ilethe i-'26 cm radio astronomy' phambili ocwaningweni lwangaphambi kwesikhathi. indawo yonke futhi usisize kakhulu ekwembuleni izimfihlakalo zakuqala indawo yonke. 

Uma kukhulunywa ngesifundo se indawo yonke yokuqala, igama elisanda kwethulwa I-James Webb Space Telescope (JWST) kuvela emqondweni wethu. I-JWST, umlandeli wempumelelo enkulu hubble i-telescope, i-a isikhala-i-infrared observatory esekelwe, ehlomele ukuthwebula amasignali okubona/kwe-infrared avela ezinkanyezini zakuqala kanye nemithala eyakhiwe endaweni Universe ngokushesha ngemva kweBig Bang¹. Nokho, I-JWST inomkhawulo kuze kube manje ngokucosha amasiginali kusukela kunkathi engathathi hlangothi ye indawo yonke yokuqala uyathinteka.  

Ithebula: Izinkathi emlandweni we indawo yonke kusukela kuBig Bang  

(Umthombo: Ifilosofi yeCosmology - 21 cm ingemuva. Itholakala ku- http://philosophy-of-cosmology.ox.ac.uk/images/21-cm-background.jpg)  

Kuze kube yiminyaka engama-380 k ngemva kokuqhuma okukhulu, i- indawo yonke yayigcwele igesi e-ionized futhi yayingacacile ngokuphelele. Phakathi kweminyaka engama-380k - 400 million, i indawo yonke kwase kungathathi hlangothi futhi kwaphumela obala. Inkathi yokuvuselelwa kabusha yaqala ngemva kwalesi sigaba iqala izigidi ezingu-400 ngemva kokuqhuma okukhulu.  

Phakathi nenkathi yokungathathi hlangothi yasekuqaleni indawo yonke, lapho indawo yonke yayigcwele amagesi angathathi hlangothi futhi isobala, akukho signali yokubona eyakhishwa (yingakho ibizwa ngokuthi i-dark age). Izinto ezihlanganisiwe azikhiphi ukukhanya. Lokhu kudala inselele ekufundeni kusenesikhathi Universe yenkathi yokungathathi hlangothi. Kodwa-ke, imisebe ye-microwave engu-21 cm ubude (ihambisana no-1420 MHz) ekhishwa i-cosmic hydrogen ebandayo, engathathi hlangothi phakathi nale nkathi ngenxa yoshintsho lwe-hyperfine (kusuka ku-parallel spin ukuya ekuzinzeni okwengeziwe kwe-anti-parallel spin) inikeza amathuba kubacwaningi. Le misebe ye-microwave engu-21 cm izoshintshwa ngokubomvu lapho ifika eMhlabeni futhi izobonwa kumafrikhwensi angu-200MHz kuya ku-10 MHz njengamaza omsakazo.^2,3.  

21 cm i-radio astronomy: Ukubhekwa kwamasignali e-cosmic hydrogen angamasentimitha angama-21 kunikeza enye indlela yocwaningo lwakuqala. indawo yonke ikakhulukazi sesigaba senkathi engathathi hlangothi ebesingenakho ukukhipha ukukhanya. Lokhu futhi kungasazisa mayelana ne-physics entsha njengokusatshalaliswa kwezinto ngokuhamba kwesikhathi, amandla amnyama, izinto ezimnyama, inqwaba ye-neutrino, kanye nokwehla kwamandla emali.².  

Kodwa-ke, amasiginali angama-21-cm akhishwa yi-cosmic hydrogen ekuqaleni indawo yonke isigaba asikho. Kulindeleke ukuthi ibe buthaka ngokwedlulele (cishe izikhathi eziyizinkulungwane eziyikhulu zibe buthakathaka kunezinye izimpawu zomsakazo nazo eziphuma esibhakabhakeni). Ngenxa yalokho, le ndlela isewusana.  

Ngo-2018, abacwaningi babike ukutholwa kwesiginali yomsakazo enjalo ngemvamisa ye-78 MHz iphrofayili yayo yayihambisana kakhulu nokulindelwe kwesiginali engamasentimitha angama-21 ekhishwa yi-primordial cosmic hydrogen.⁴. Kodwa lokhu kutholwa kwesignali yomsakazo yokuqala engu-21-cm akukwazanga ukuqinisekiswa ngokuzimele yingakho ukwethembeka kokuhlolwa akukwazanga ukusungulwa kuze kube manje. Inkinga enkulu ibonakala iwukungcoliswa kwamasignali omsakazo angaphambili.  

Ingqopha-mlando yakamuva umbiko we-Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) ngomhla zingama-21 kuJulayi 2022. I-REACH izosebenzisa indlela yokuhlola inoveli ukuze ithole lezi zimpawu zomsakazo we-cosmic ezintekenteke ngaleyo ndlela inikeza ithemba elisha lokuqinisekisa amasignali we-cosmic angamasentimitha angama-21.  

I-Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) iwukuhlola okusesibhakabhakeni okungu-21-cm. Lokhu kuhloswe ukuthuthukisa ukubonwa ngokuphatha izinkinga amathuluzi abhekene nazo ezihlobene nensalela yezimpawu zesistimu kudatha. Igxile ekutholeni nasekuchazeni ngokuhlanganyela i-systematics kanye nengaphambili kanye nesignali ye-cosmological kusetshenziswa izibalo ze-Bayesia. I ukuhlolwa ibandakanya ukubhekwa kanyekanye okunama-antenna amabili ahlukene, isistimu ye-ultra-wideband (ububanzi be-redshift cishe ngo-7.5 ukuya ku-28) kanye nesikali somamukeli esisekelwe ezilinganisweni zangaphakathi kwenkundla.  

Lokhu kuthuthukiswa kubalulekile uma kubhekwa amandla ayo okuba elinye lamathuluzi angcono kakhulu (futhi kubiza ngempumelelo kakhulu nge-vis-a-vis isikhala-based observatories like UJames Webb) ukufunda kusenesikhathi indawo yonke kanye nethuba lokungenisa i-physics eyisisekelo entsha.  

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References:  

1. Prasad U., 2021.James Webb Space Telescope (JWST): I-First Space Observatory enikelwe esifundweni se-Early Universe. Isayensi yaseYurophu. Kuthunyelwe ngomhla ka-6 Novemba 2021. Itholakala e- https://www.scientificeuropean.co.uk/sciences/space/james-webb-space-telescope-jwst-the-first-space-observatory-dedicated-to-the-study-of-early-universe/

2. U-Pritchard JA no-Loeb A., 2012. 21 cm i-cosmology ekhulwini lama-21. Imibiko ngeNtuthuko kuPhysics 75 086901. Itholakala ku https://iopscience.iop.org/article/10.1088/0034-4885/75/8/086901. I-Preprint e-arXiv itholakala ku- https://arxiv.org/abs/1109.6012  inguqulo ye-pdf  https://arxiv.org/pdf/1109.6012.pdf 

3. Oxford University. Ifilosofi yeCosmology - ingemuva le-21 cm. Itholakala ngo http://philosophy-of-cosmology.ox.ac.uk/21cm-background.html 

4. Bowman, J., Rogers, A., Monsalve, R. et al. Iphrofayili yokumuncwa egxile ku-78 megahertz esibukweni esimaphakathi esibhakabhakeni. Imvelo 555, 67–70 (2018). https://doi.org/10.1038/nature25792 

5. de Lera Acedo, E., de Villiers, DIL, Razavi-Ghods, N. et al. I-radiometer REACH yokuthola isignali ye-hydrogen engu-21-cm ukusuka ku-redshift z ≈ 7.5–28. U-Nat Astron (2022). https://doi.org/10.1038/s41550-022-01709-9  

6. U-Eloy de Lera Acedo 2022. Kwembula izimfihlakalo Zomhlaba Owusana nge-REACH radiometer. Itholakala ku-inthanethi ku-  https://astronomycommunity.nature.com/posts/u 

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