The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps: Detecting anisotropic ionized bubbles

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Majumdar, Suman (författare)

The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps : Detecting anisotropic ionized bubbles

Artikel/kapitelEngelska2011

Förlag, utgivningsår, omfång ...

2011-02-09
Oxford University Press (OUP),2011
printrdacarrier

Nummerbeteckningar

LIBRIS-ID:oai:DiVA.org:su-52886
https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-52886URI
https://doi.org/10.1111/j.1365-2966.2011.18223.xDOI

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Språk:engelska
Sammanfattning på:engelska

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Ämneskategori:ref swepub-contenttype
Ämneskategori:art swepub-publicationtype

Anmärkningar

The detection of ionized bubbles around quasars in redshifted 21-cm maps is possibly one of the most direct future probes of reionization. We consider two models for the growth of spherical ionized bubbles to study the apparent shapes of the bubbles in redshifted 21-cm maps, taking into account the finite light travel time (FLTT) across the bubble. We find that the FLTT, whose effect is particularly pronounced for large bubbles, causes the bubble's image to continue to grow well after it's actual growth is over. There are two distinct FLTT distortions in the bubble's image: (i) its apparent center is shifted along the line of sight (LOS) towards the observer from the quasar; (ii) it's shape is anisotropic along the LOS. The bubble initially appears elongated along the LOS. This is reversed in the later stages of growth where the bubble appears compressed. The FLTT distortions are expected to have an impact on matched filter bubble detection where it is most convenient to use a spherical template for the filter. We find that the best matched spherical filter gives a reasonably good estimate of the size and the shift in the center of the anisotropic image. The mismatch between the spherical filter and the anisotropic image causes a 10 - 20% degradation in the SNR relative to that of a spherical bubble. We conclude that a spherical filter is adequate for bubble detection. The FLTT distortions do not effect the lower limits for bubble detection with 1000 hr of GMRT observations. The smallest spherical filter for which a detection is possible has comoving radii 24 Mpc and 33 Mpc for a 3-sigma and 5-sigma detection respectively, assuming a neutral fraction 0.6 at z \sim 8.

Ämnesord och genrebeteckningar

NATURVETENSKAP Fysik Astronomi, astrofysik och kosmologi hsv//swe
NATURAL SCIENCES Physical Sciences Astronomy, Astrophysics and Cosmology hsv//eng
methods: data analysis - cosmology: theory: - diffuse radiation
Cosmology
Kosmologi
Astronomy
astronomi

Biuppslag (personer, institutioner, konferenser, titlar ...)

Bharadwaj, Somnath (författare)
Datta, Kanan K.Stockholms universitet,Institutionen för astronomi,Oskar Klein-centrum för kosmopartikelfysik (OKC) (författare)
Choudhury, Tirthankar Roy (författare)
Stockholms universitetInstitutionen för astronomi (creator_code:org_t)

Sammanhörande titlar

Ingår i:Monthly notices of the Royal Astronomical Society: Oxford University Press (OUP)413:2, s. 1409-14180035-87111365-2966

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NATURVETENSKAP: NATURVETENSKAP; och Fysik; och Astronomi astrof ...

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Av lärosätet: Stockholms universitet

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