{"id":6,"date":"2018-12-25T18:32:26","date_gmt":"2018-12-25T18:32:26","guid":{"rendered":"https:\/\/ioanazelko.com\/?page_id=6"},"modified":"2024-01-18T16:41:38","modified_gmt":"2024-01-18T16:41:38","slug":"research","status":"publish","type":"page","link":"https:\/\/ioanazelko.com\/ro\/research\/","title":{"rendered":"Cercetare"},"content":{"rendered":"
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Publica\u0163ii<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Link-uri c\u0103tre mine Publica\u0163ii ADS<\/a> \u0219i arXiv preprints<\/a>.<\/p>\n

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\"orcid<\/a>\u00a0https:\/\/orcid.org\/0000-0002-7588-976X<\/a><\/p>\n

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Harta temperaturii praf galactic 3D<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Not\u0103: datele pentru hart\u0103 sunt disponibile la cerere prin e-mail, cu num\u0103rul de bins de distan\u021b\u0103, parametrul nside, personalizabil pentru aplica\u021bia dvs.; lucr\u0103m la alegerea celei mai bune modalit\u0103\u021bi de distribuire online.<\/p>\n

Cercet\u0103torii au folosit mult timp emisia de praf pentru a mapa praful \u00een 2D, iar \u00een ultimii ani \u00eenro\u0219irea stelelor a fost folosit\u0103 pentru a mapa praful \u00een 3D. Cu toate acestea, tehnica combin\u0103rii informa\u021biilor 3D din \u00eenro\u0219ire cu datele de emisie este \u00eenc\u0103 \u00een stadiu incipient. \u00cen aceast\u0103 lucrare, am combinat aceste dou\u0103 seturi de date pentru a crea prima hart\u0103 3D a temperaturii prafului galatic la scar\u0103 mare. Mai jos pute\u021bi vedea un videoclip cu rezultatul:  Vizualiz\u0103ri 3D <\/span>a h\u0103r\u021bii de 27\u2032 a temperaturii prafului galactic \u0219i a densit\u0103\u021bii acestuia. Intensitatea este propor\u021bional\u0103 cu densitatea, iar varia\u021bia RGB este dependent\u0103 de temperatur\u0103. Albastrul este sensibil la cea mai scurt\u0103 lungime de und\u0103 (praf mai fierbinte, ~20K), ro\u0219u la lungimi de und\u0103 mai lungi (praf rece) \u0219i verde la valori intermediare. Perspectiva prezentat\u0103 aici prezint\u0103 o captur\u0103 de ecran a plas\u0103rii camerei f\u0103c\u00e2nd o bucl\u0103 de 25 de bucle \u00een jurul Soarelui, privind \u00een planul galactic c\u0103tre anticentru (180 longitudine galactic\u0103), c\u0103tre norii Orion, Taur, Perseus \u0219i California. 
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MATERIEI \u00ceNTUNECELE \u0218I LENTILE PUTERNICE GRAVITA\u021aIONALE<\/h2><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Omenirea nu \u0219tie din ce este f\u0103cut\u0103 majoritatea universului. Planetele, stelele, galaxiile \u0219i toate elementele din tabelul periodic al chimiei alc\u0103tuiesc mai pu\u021bin de 5% din univers. Se crede c\u0103 dou\u0103 componente necunoscute p\u00e2n\u0103 acum, numite materie \u00eentunecat\u0103 \u0219i energie \u00eentunecat\u0103, alc\u0103tuiesc restul. Ar\u0103t\u0103m c\u0103 m\u0103sur\u0103torile precise ale efectului gravita\u021biei asupra luminii exclud unii candida\u021bi populari de particule de materie \u00eentunecat\u0103 numi\u021bi neutrini sterili. Materia \u00eentunecat\u0103 nu interac\u021bioneaz\u0103 cu lumina, a\u0219a c\u0103 nu putem s\u0103-i facem o poz\u0103 \u0219i s\u0103 o observ\u0103m direct. Cu toate acestea, are mas\u0103 \u0219i, astfel, exercit\u0103 o atrac\u021bie gravita\u021bional\u0103 asupra altor materii \u0219i chiar asupra luminii. C\u00e2nd lumina de la un obiect luminos trece \u00een apropierea unei galaxii care con\u021bine materie \u00eentunecat\u0103, materia \u00eentunecat\u0103 ac\u021bioneaz\u0103 ca o lentil\u0103 \u0219i se pot forma mai multe imagini ale obiectului luminos. Pozi\u021bia \u0219i luminozitatea imaginilor multiple ne spun despre materia de baz\u0103 care face obiectivul. Folosind aceast\u0103 tehnic\u0103 am ar\u0103tat c\u0103, dac\u0103 materia \u00eentunecat\u0103 este format\u0103 din particule ipotetice numite \u201eneutrini sterili\u201d, numite dup\u0103 interac\u021biunea lor limitat\u0103 cu for\u021bele naturii, masele lor trebuie s\u0103 fie mai mari dec\u00e2t permise anterior.<\/span><\/p>\n

Lucrarea mea privind punerea de constr\u00e2ngeri asupra modelelor de neutrini sterili folosind lentile gravita\u021bionale puternice poate fi citit\u0103 aici:<\/span><\/p>\n

Zelko et al 2022, Physical Review Letters, PRL:\u00a0https:\/\/journals.aps.org\/prl\/abstract\/10.1103\/PhysRevLett.129.191301<\/a><\/p>\n

\u00a0\u00cen munca mea continu\u0103,\u00a0<\/span>M\u0103 uit s\u0103 folosesc lentile puternice pentru a impune constr\u00e2ngeri modelelor de materie \u00eentunecat\u0103. Pentru anumite clase de teorii ale materiei \u00eentunecate, \u00eencerc s\u0103 \u00eemi dau seama care ar fi cre\u0219terea structurii \u0219i ce observabile ar avea, ceea ce duce la compara\u021bii cu datele.<\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Probing Dark Matter with Adaptive-optics based Flux Ratio Anomalies: Photometric and Astrometric Precision<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Gravitational lensing is not just a beautiful cosmic occurrence; it’s a powerful probe into the universe’s most elusive components. Our research focuses on using this phenomenon to test the existence of dark subhalos, as predicted by the cold (and not-so-cold) dark matter models. These are potentially massive structures that remain unseen, silently shaping the cosmos.<\/div>\n<\/div>\n
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The effectiveness of gravitational lensing as a tool depends greatly on the photometric and astrometric precision and accuracy we can achieve. In our study, we simulate and quantify how upcoming adaptive optics systems and advanced instruments on ground-based telescopes will transform our capabilities.<\/div>\n
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\"\ud83d\ude80\"<\/span> A Glimpse into the Future with Advanced Telescopes:<\/div>\n
We’ve focused our simulations on state-of-the-art systems planned for the Keck Telescope (like OSIRIS + KAPA and LIGER + KAPA) and the groundbreaking Thirty Meter Telescope (TMT; with IRIS + NFIRAOS). Our findings are genuinely exciting \u2013 these new systems will achieve dramatic improvements over current ones, offering unprecedented photometric and astrometric precision.<\/div>\n
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\u00a0Implications for Quadruply Imaged Quasars:<\/div>\n
For typical quadruply imaged quasars, we’re looking at narrow line flux ratio errors below 2%, and astrometric precision to the submilliarcsecond. This level of detail is simply revolutionary and will allow us to observe the universe like never before.<\/div>\n
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\"\u23f1\ufe0f\"<\/span> Efficiency Meets Discovery:<\/div>\n
One of the most promising aspects of our research is the efficiency these new systems bring. With the TMT, for instance, the required exposure times per system are just a few minutes. This efficiency enables the follow-up of the 100-1000 systems expected to be discovered by powerful telescopes like Rubin, Euclid, and Roman.<\/div>\n<\/div>\n
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As we stand on the brink of these incredible advancements in astrophysics, I’m filled with anticipation for the mysteries we’ll unravel and the new chapters of cosmic history we’ll write.<\/div>\n<\/div>\n
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Read our full work here: Zelko et al. 2023 https:\/\/arxiv.org\/abs\/2311.17140<\/a><\/div>\n<\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Praf de stele \u0219i cosmologie<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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\u00cen timpul doctoratului, m-am uitat la praful interstelar \u0219i impactul acestuia asupra experimentelor de fundal cu microunde cosmice. Am lucrat \u00een grupul de cercetare al profesorului de la Harvard Douglas P. Finkbeiner.<\/p>\n

Am finalizat un nou studiu semnificativ al boabelor de praf interstelar, varia\u021biile lor \u00een dimensiune \u0219i compozi\u021bie \u0219i efectele asupra extinc\u021biei interstelare.<\/p>\n

Zelko \u0219i Finkbeiner 2020:\u00a0\u00a0<\/span>https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/abbb8d<\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Pe baza acelei lucr\u0103ri, am studiat contribu\u021bia prafului interstelar \u0219i non-galactic la detectarea distorsiunilor spectrale ale fundalului cosmic cu microunde.<\/p>\n

Zelko \u0219i Finkbeiner 2021:\u00a0https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/abfa12<\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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\u00cen cele din urm\u0103, am creat prima hart\u0103 3D a temperaturii prafului mediu interstelar. Lucrarea este publicat\u0103 ca al treilea capitol al tezei mele \u0219i este acum \u00een pre-tip\u0103rire ca articol.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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EPOCA REIONIZ\u0102RII<\/h2><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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\u00cen timpul petrecut la MIT, cercet\u0103rile mele s-au concentrat pe construirea unui telescop interferometru, ca parte a grupului de cercetare\u00a0<\/span>conduce\u00a0de profesorul MIT Max Tegmark. Am fost direct responsabil cu crearea conductei de procesare a datelor \u00eencruci\u0219ate \u00een timp real, programarea FPGA-urilor pe pl\u0103ci ROACH, pentru un design de 64 de antene. Am instalat telescopul care a preluat date cu succes \u00een Maine, valid\u00e2nd designul.<\/span><\/p>\n

Pute\u021bi vedea un videoclip cu rezultatul aici:<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Lista publica\u021biilor rezultate \u00een urma acestei lucr\u0103ri:<\/span><\/p>\n