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Detection of isolated Population III stars with 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).
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
2013 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 429, no 4, 3658-3664 p.Article in journal (Refereed) Published
Abstract [en]

The first Population III stars are predicted to form in minihaloes at z approximate to 10-30. The James Webb Space Telescope (JWST), tentatively scheduled for launch in 2018, will probably be able to detect some of the first galaxies, but whether it will also be able to detect the first stars remains more doubtful. Here, we explore the prospects of detecting an isolated Population III star or a small cluster of Population III stars down to z = 2 in either lensed or unlensed fields. Our calculations are based on realistic stellar atmospheres and take into account the potential flux contribution from the surrounding HII region. We find that unlensed Population III stars are beyond the reach of JWST, and that even lensed Population III stars will be extremely difficult to detect. However, the main problem with the latter approach is not necessarily that the lensed stars are too faint, but that their surface number densities are too low. To detect even one 60 M-circle dot Population III star when pointing JWST through the galaxy cluster MACS J0717.5+3745, the lensing cluster with the largest Einstein radius detected so far, the cosmic star formation rate of Population III stars would need to be approximately an order of magnitude higher than predicted by the most optimistic current models.

Place, publisher, year, edition, pages
2013. Vol. 429, no 4, 3658-3664 p.
Keyword [en]
stars: Population III, dark ages, reionization, first stars
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
URN: urn:nbn:se:su:diva-90800DOI: 10.1093/mnras/sts653ISI: 000318272600074OAI: oai:DiVA.org:su-90800DiVA: diva2:627770
Funder
Swedish Research Council, 2011-5349
Note

AuthorCount:4;

Available from: 2013-06-12 Created: 2013-06-11 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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