Star forming galaxies at z≈6 and reionization

Bunker, Andrew J.; Stanway, Elizabeth R.; Ellis, Richard S.; McMahon, R. G.; Eyles, Lauarence; Lacy, Mark

doi:10.1016/j.newar.2005.11.006

Cited by 24 publications

(27 citation statements)

References 44 publications

(30 reference statements)

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“…The observational data for z ≳ 6 are uncertain and differ by up to a factor of 10 between different studies; compare, for example, the results of Bunker et al (2006) and Bouwens et al (2008). Our high‐resolution simulations favour a modest drop of ∼50 per cent in from its peak at z ∼ 2 to z = 6, with most stars forming in faint galaxies, which have SFRs of ≲0.1 M ⊙ yr −1 .…”

Section: The Evolution Of Cosmic Star Formationmentioning

confidence: 75%

Galaxies��intergalactic medium interaction calculation �� I. Galaxy formation as a function of large-scale environment

Crain

Theuns

Vecchia

et al. 2009

Monthly Notices of the Royal Astronomical Society

250

297

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We present the first results of hydrodynamical simulations that follow the formation of galaxies to the present day in nearly spherical regions of radius ∼20 h−1 Mpc drawn from the Millennium Simulation (Springel et al.). The regions have mean overdensities that deviate by (−2, −1, 0, +1, +2)σ from the cosmic mean, where σ is the rms mass fluctuation on a scale of ∼20 h−1 Mpc at z= 1.5. The simulations have mass resolution of up to ∼106 h−1 M⊙, cover the entire range of large‐scale cosmological environments, including rare objects such as massive clusters and sparse voids, and allow extrapolation of statistics to the (500 h−1 Mpc)3 Millennium Simulation volume as a whole. They include gas cooling, photoheating from an imposed ionizing background, supernova feedback and galactic winds, but no AGN. In this paper, we focus on the star formation properties of the model. We find that the specific star formation rate density at z≲ 10 varies systematically from region to region by up to an order of magnitude, but the global value, averaged over all volumes, closely reproduces observational data. Massive, compact galaxies, similar to those observed in the GOODS fields (Wiklind et al.), form in the overdense regions as early as z= 6, but do not appear in the underdense regions until z∼ 3. These environmental variations are not caused by a dependence of the star formation properties on environment, but rather by a strong variation of the halo mass function from one environment to another, with more massive haloes forming preferentially in the denser regions. At all epochs, stars form most efficiently in haloes of circular velocity vc∼ 250 km s−1. However, the star formation history exhibits a form of ‘downsizing’ (even in the absence of AGN feedback): the stars comprising massive galaxies at z= 0 have mostly formed by z= 1−2, whilst those comprising smaller galaxies typically form at later times. However, additional feedback is required to limit star formation in massive galaxies at late times.

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Section: The Evolution Of Cosmic Star Formationmentioning

confidence: 75%

Galaxies��intergalactic medium interaction calculation �� I. Galaxy formation as a function of large-scale environment

Crain

Theuns

Vecchia

et al. 2009

Monthly Notices of the Royal Astronomical Society

250

297

View full text Add to dashboard Cite

show abstract

“…Although QSOs are expected to be the main contributor of ionizing photons at the bright end of the luminosity function ( LF) of ionizing sources, the QSO population alone cannot account for all the required ionizing photons ( Willott et al 2005), and star-forming galaxies like Lyman break galaxies (LBGs) and Ly emitters ( LAEs) at the reionization epoch are the only alternatives that could dominate at the faint end. The census of observable galaxies at this epoch is sensitive to the ionization fraction of the universe ( Yan & Windhorst 2004;Malhotra & Rhoads 2004;Bouwens et al 2005;Stiavelli et al 2005;Bunker et al 2006). It is expected that the surrounding neutral intergalactic medium (IGM) attenuates the Ly photons so significantly that the number density decline of LAEs provides a useful observational constraint on the reionization epoch (Haiman & Spaans 1999;Rhoads & Malhotra 2001;Hu et al 2002).…”

Section: Introductionmentioning

confidence: 99%

The End of the Reionization Epoch Probed by Lyα Emitters atz= 6.5 in the Subaru Deep Field

Kashikawa

Shimasaku

Malkan

et al. 2006

ApJ

425

713

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We report an extensive search for Ly emitters (LAEs) at z ¼ 6:5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at z ¼ 6:5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58 LAEs, we have derived a more accurate Ly luminosity function of LAEs at z ¼ 6:5, which reveals an apparent deficit at the bright end of $0.75 mag fainter L Ã , compared with that observed at z ¼ 5:7. The difference in the LAE luminosity functions between z ¼ 5:7 and 6.5 is significant at the 3 level, which is reduced to 2 when cosmic variance is taken into account. This result may imply that the reionization of the universe has not been completed at z ¼ 6:5. We found that the spatial distribution of LAEs at z ¼ 6:5 was homogeneous over the field. We discuss the implications of these results for the reionization of the universe.

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“…Large samples of galaxies at z > 5 exist and allow us to study with unprecedented detail the early epoch of galaxy assembly and star formation history (see, e.g., Steidel et al 1996;Madau et al 1996;Giavalisco 2002;Bouwens et al 2004;Mobasher et al 2005;Beckwith et al 2006;Oesch et al 2007), as well as to constrain the properties of sources responsible for reionization (see, e.g., Stiavelli et al 2004;Yan & Windhorst 2004;Bunker et al 2006). Hunting for high-z galaxies usually follows two complementary approaches.…”

Section: Introductionmentioning

confidence: 99%

Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High‐zSurveys

Trenti

Stiavelli

2008

ApJ

360

353

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We study cosmic variance in deep high-redshift surveys and its influence on the determination of the luminosity function for high-redshift galaxies. For several survey geometries relevant for Hubble Space Telescope (HST ) and James Webb Space Telescope (JWST ) instruments, we characterize the distribution of the galaxy number counts. This is obtained by means of analytic estimates via the two-point correlation function in extended Press-Schechter theory, as well as by using synthetic catalogs extracted from N-body cosmological simulations of structure formation. We adopt a simple luminosity-dark halo mass relation to investigate the effects of environment on the fitting of the luminosity function. We show that in addition to variations of the normalization of the luminosity function, a steepening of its slope is also expected in underdense fields, similar to what is observed within voids in the local universe. Therefore, to avoid introducing artificial biases, caution must be taken when attempting to correct for field underdensity, such as in the case of the HST UDF i-dropout sample, which exhibits a deficit of bright counts with respect to the average counts in GOODS. A public version of the cosmic variance calculator based on the two-point correlation function integration is available on the Web at STScI.

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Star forming galaxies at z≈6 and reionization

Cited by 24 publications

References 44 publications

Galaxies��intergalactic medium interaction calculation �� I. Galaxy formation as a function of large-scale environment

Galaxies��intergalactic medium interaction calculation �� I. Galaxy formation as a function of large-scale environment

The End of the Reionization Epoch Probed by Lyα Emitters atz= 6.5 in the Subaru Deep Field

Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High‐zSurveys

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Star forming galaxies at z≈6 and reionization

Cited by 24 publications

References 44 publications

Galaxies���intergalactic medium interaction calculation ��� I. Galaxy formation as a function of large-scale environment

Galaxies���intergalactic medium interaction calculation ��� I. Galaxy formation as a function of large-scale environment

The End of the Reionization Epoch Probed by Lyα Emitters atz= 6.5 in the Subaru Deep Field

Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High‐zSurveys

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Galaxies��intergalactic medium interaction calculation �� I. Galaxy formation as a function of large-scale environment

Galaxies��intergalactic medium interaction calculation �� I. Galaxy formation as a function of large-scale environment