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Detecting gravitationally lensed Population III galaxies with the Hubble Space Telescope and the James Webb Space Telescope
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
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2012 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 427, no 3, 2212-2223 p.Article in journal (Refereed) Published
Abstract [en]

Small galaxies consisting entirely of Population III (pop III) stars may form at high redshifts, and could constitute one of the best probes of such stars. Here, we explore the prospects of detecting gravitationally lensed pop III galaxies behind the galaxy cluster J0717.5+3745 (J0717) with both the Hubble Space Telescope (HST) and the upcoming James Webb Space Telescope (JWST). By projecting simulated catalogues of pop III galaxies at z similar to 715 through the J0717 magnification maps, we estimate the lensed number counts as a function of flux detection threshold. We find that the ongoing HST survey Cluster Lensing And Supernova survey with Hubble (CLASH), targeting a total of 25 galaxy clusters including J0717, potentially could detect a small number of pop III galaxies if similar to 1 per cent of the baryons in these systems have been converted into pop III stars. Using JWST exposures of J0717, this limit can be pushed to similar to 0.1 per cent of the baryons. Ultradeep JWST observations of unlensed fields are predicted to do somewhat worse, but will be able to probe pop III galaxies with luminosities intermediate between those detectable in HST/CLASH and in JWST observations of J0717. We also explain how current measurements of the galaxy luminosity function at z = 710 can be used to constrain pop III galaxy models with very high star formation efficiencies (similar to 10 per cent of the baryons converted into pop III stars).

Place, publisher, year, edition, pages
2012. Vol. 427, no 3, 2212-2223 p.
Keyword [en]
stars: Population III, galaxies: high-redshift, dark ages, reionization, first stars
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
URN: urn:nbn:se:su:diva-84799DOI: 10.1111/j.1365-2966.2012.22078.xISI: 000311414800026OAI: oai:DiVA.org:su-84799DiVA: diva2:581554
Funder
Swedish Research Council, 2011-5349
Note

AuthorCount:9;

Available from: 2013-01-02 Created: 2013-01-02 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Gravitational lensing as a probe of the first stars and galaxies
Open this publication in new window or tab >>Gravitational lensing as a probe of the first stars and galaxies
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis investigates the potential for detection and identification of primordial stars, galaxies, and supernovae at high redshift.

Simulations indicate that the first Population III stars should appear in minihalos of mass M = 105-106 Msol at z ≈ 10-30. To assess the detectability of these objects, theoretical models of these stars and their surrounding HII regions are used. We assess the plausibility of detection with the upcoming James Webb Space Telescope (JWST), using the gravitational lensing provided by the galaxy cluster MACSJ0717.5+3745. The conclusion is that the detection of these objects is highly improbable but not impossible.

To investigate the prospects of detecting and identifying the first galaxies, the spectral synthesis code Yggdrasil is introduced. According to this code, JWST may be able to detect Population III galaxies with stellar masses as low as 105 Msol at z ≈ 10 in unlensed fields. We find that, over limited redshift intervals, it could be possible to use Hubble Space Telescope (HST) and/or JWST broadband color criteria to single out Population III galaxy candidates.

The prospects of detecting gravitationally lensed Population III galaxies with JWST and HST is investigated. A lower limit to detect ≈1 Population III galaxy of ε ≈ 10-2 (HST/CLASH) and ε ≈ 10-3 (JWST using MACS J0717.5+3745 as lens) is derived, where ε is the baryon fraction converted to Population III stars in a host halo.

By fitting HST/CLASH data to Yggdrasil and comparison grids, two Population III galaxy candidates are discovered. These two candidates are the first Population III galaxy candidates discovered at z > 6.5. A highly-magnified and doubly lensed extremely high-redshift (z ≈ 7.8) object is also identified.

Finally the prospects of detecting core-collapse (CC) supernovae (SN) from the first galaxies at z ≈ 5-12 are investigated. The prediction is that no primordial SN is detectable, but 2-3 CC SN should be discovered by the HST/CLASH.

Place, publisher, year, edition, pages
Stockholm: Department of Astronomy, Stockholm University, 2015. 54 p.
Keyword
stars: Population III, first stars, Galaxies: high-redshift, Galaxies: Population III, dark ages, reionization, techniques: photometric
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
urn:nbn:se:su:diva-110070 (URN)978-91-7649-068-6 (ISBN)
Public defence
2015-01-30, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Submitted. Paper 6: Submitted. Paper 7: Manuscript.

Available from: 2015-01-08 Created: 2014-12-05 Last updated: 2015-01-12Bibliographically approved

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Zackrisson, ErikRydberg, Claes-ErikGuaita, LuciaÖstlin, Göran
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