Startsida
Hjälp
Sök i LIBRIS databas

     

 

Sökning: onr:2j80ks960lk9x4tk > Understanding the l...

Understanding the large-scale structure of the the21-cm signal originating from the Epoch of Reionisation [Elektronisk resurs]

Georgiev, Ivelin, 1995- (författare)
Mellema, Garrelt (preses)
Jasche, Jens (preses)
Schneider, Aurel (opponent)
Numerical Astrophysics Group (medarbetare)
Stockholms universitet Naturvetenskapliga fakulteten (utgivare)
Publicerad: Sweden : Stockholm University, 2022
Engelska 89
Läs hela texten
Läs hela texten
  • E-bokAvhandling(Lic.-avh. Stockholm : Stockholms universitet, 2022)
Sammanfattning Ämnesord
Stäng  
  • The first billion years from the beginning of the Universe is the focus of multiple astronomical facilities in the upcoming decade. This unique era is marked by the formation of the first stars and galaxies, which release ionising radiation into the intergalactic medium(IGM). As a result, these sources initiate a period during which the cold and dense IGM, primarily consisting of neutral hydrogen (H I ), is heated and ionised. We refer to this era as the Epoch of Reionisation (EoR). How the EoR transpired hence depends on the properties of these ionising sources, and this forms a vital piece to the puzzle of understanding the early Universe. This licentiate thesis aims to educate the reader on the power spectrum (PS) statistic of the 21-cm signal from H I  during the EoR. The PS is a prospective observable by radio interferometers, such as the Low-Frequency Array (LOFAR) and the future Square Kilometre Array (SKA). It is an essential stepping stone in comprehending the dominant physical processes affecting the IGM at a given length scale during the EoR. In Paper I, we analyse the decomposition of the 21-cm PS from Lidz et al. (2007) (eq. 2)and study the evolution of its terms. We conduct our investigation for a set of C 2 -Ray and 21cmFAST simulations with volumes of (714 cMpc) 3 , concentrating on large-scales (k < 0.3 Mpc −1 ) as the signal-to-noise ratio of observing these scales will be high. We find that the 21-cm PS tracks the PS of neutral hydrogen fluctuations, which itself past a certain scale tracks the matter PS after a global ionisation fraction of x̄ HII ∼ 0.1. Hence, the 21-cm PS possesses a two-regime form for which the large-scale PS is a biased version of the cosmological density field and the small-scale PS depends on the astrophysics of the EoR. We construct a bias parameter to explore whether the 21-cm PS can be used as a probe of cosmology on large k-scales. We discover a transition feature for both simulations, following the k trans ≈ 2/λMFP empirical formula. The transition scale between the scale-independent and scale-dependent bias regimes is directly related to the value of the mean free path of ionising photons (λ MFP ). 

Ämnesord

Natural Sciences  (hsv)
Physical Sciences  (hsv)
Astronomy, Astrophysics and Cosmology  (hsv)
Naturvetenskap  (hsv)
Fysik  (hsv)
Astronomi, astrofysik och kosmologi  (hsv)
Astronomy  (su)
astronomi  (su)

Genre

government publication  (marcgt)

Indexterm och SAB-rubrik

reionisation
cosmology
21-cm
large-scale structure
Inställningar Hjälp

Uppgift om bibliotek saknas i LIBRIS

Kontakta ditt bibliotek, eller sök utanför LIBRIS. Se högermenyn.

Om LIBRIS
Sekretess
Hjälp
Fel i posten?
Kontakt
Teknik och format
Sök utifrån
Sökrutor
Plug-ins
Bookmarklet
Anpassa
Textstorlek
Kontrast
Vyer
LIBRIS söktjänster
SwePub
Uppsök

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

Copyright © LIBRIS - Nationella bibliotekssystem

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy