Searching for the first stars with the<i>Gaia</i>mission

Krone-Martins, A.; Ishida, Emille E. O.; Ciardi, B.

doi:10.1051/0004-6361/201118746

Cited by 10 publications

(7 citation statements)

References 90 publications

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“…de Souza et al 2014). The resulting lightcurves may show the characteristics of core-collapse SNe (Meiksin & Whalen 2013;Whalen et al 2013b,g), pair-instability SNe (Scannapieco et al 2005;Weinmann & Lilly 2005;Hummel et al 2012;Pan et al 2012;de Souza et al 2013b;Whalen et al 2013aWhalen et al ,f, 2014, gamma-ray bursts (Bromm & Loeb 2002;Choudhury & Srianand 2002;Islam et al 2004;Natarajan et al 2005;Bromm & Loeb 2006;Hirose et al 2006;Belczynski et al 2007;Inoue et al 2007;Naoz & Barkana 2007;Salvaterra et al 2008;Komissarov & Barkov 2010;Mészáros & Rees 2010;Campisi et al 2011;de Souza et al 2011;Toma et al 2011;de Souza et al 2012;Nakauchi et al 2012;Wang et al 2012;Macpherson et al 2013;Figure 12: Zoom-in on the gas cloud that forms at the center of an atomic cooling halo, showing the number density of hydrogen nuclei. Clockwise from the top left, the width of the individual cubes are 10 pc, 1 pc, 0.1 pc, 1000 au, 100 au, and 10 au.…”

Section: Empirical Signaturesmentioning

confidence: 99%

The numerical frontier of the high-redshift Universe

Greif

2015

Comput. Astrophys.

113

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The first stars are believed to have formed a few hundred million years after the big bang in so-called dark matter minihalos with masses ∼ 10 6 M . Their radiation lit up the Universe for the first time, and the supernova explosions that ended their brief lives enriched the intergalactic medium with the first heavy elements. Influenced by their feedback, the first galaxies assembled in halos with masses ∼ 10 8 M , and hosted the first metal-enriched stellar populations. In this review, I summarize the theoretical progress made in the field of high-redshift star and galaxy formation since the turn of the millennium, with an emphasis on numerical simulations. These have become the method of choice to understand the multi-scale, multi-physics problem posed by structure formation in the early Universe. In the first part of the review, I focus on the formation of the first stars in minihalos -in particular the post-collapse phase, where disk fragmentation, protostellar evolution, and radiative feedback become important. I also discuss the influence of additional physical processes, such as magnetic fields and streaming velocities. In the second part of the review, I summarize the various feedback mechanisms exerted by the first stars, followed by a discussion of the first galaxies and the various physical processes that operate in them.

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Section: Empirical Signaturesmentioning

confidence: 99%

The numerical frontier of the high-redshift Universe

Greif

2015

Comput. Astrophys.

113

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“…Here we discuss the connection between star formation activity and the gaseous chemical properties, x mol and Z of proto-galaxies, using a Bayesian and a MLE approach with logit link. The formation of the first metal-free stars in the Universe ended the cosmic dark ages ( de Souza et al, 2011de Souza et al, , 2012Bromm, 2013;de Souza et al, 2013b;Whalen et al, 2013a,b) and began the production of elements heavier than lithium (Maio et al, 2010(Maio et al, , 2013Wise et al, 2014). Thus, a key problem in physical cosmology is to understand the environmental properties of such objects (e.g., de Souza et al, 2013a;Biffi and Maio, 2013;Salvaterra et al, 2013), born out of the pristine conditions leftover by the Big Bang.…”

Section: Star Formation Activitymentioning

confidence: 99%

The overlooked potential of Generalized Linear Models in astronomy, I: Binomial regression

Souza

Cameron

Killedar

et al. 2015

Astronomy and Computing

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Revealing hidden patterns in astronomical data is often the path to fundamental scientific breakthroughs; meanwhile the complexity of scientific inquiry increases as more subtle relationships are sought. Contemporary data analysis problems often elude the capabilities of classical statistical techniques, suggesting the use of cutting edge statistical methods. In this light, astronomers have overlooked a whole family of statistical techniques for exploratory data analysis and robust regression, the so-called Generalized Linear Models (GLMs). In this paper -the first in a series aimed at illustrating the power of these methods in astronomical applications -we elucidate the potential of a particular class of GLMs for handling binary/binomial data, the so-called logit and probit regression techniques, from both a maximum likelihood and a Bayesian perspective. As a case in point, we present the use of these GLMs to explore the conditions of star formation activity and metal enrichment in primordial minihaloes from cosmological hydro-simulations including detailed chemistry, gas physics, and stellar feedback. We predict that for a dark mini-halo with metallicity ≈ 1.3 × 10 −4 Z , an increase of 1.2 × 10 −2 in the gas molecular fraction, increases the probability of star formation occurrence by a factor of 75%. Finally, we highlight the use of receiver operating characteristic curves as a diagnostic for binary classifiers, and ultimately we use these to demonstrate the competitive predictive performance of GLMs against the popular technique of artificial neural networks.

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“…The simulation outcomes investigated here consist of seven parameters: dark-matter mass (M dm ), gas mass (Mgas), stellar mass (Mstar), star formation rate (SFR), Z, gas temperature (T), and gas molecular fraction (x mol ). We refer the reader to previous works, where more details and additional analyses about halo spin and shape distribution (de Souza et al 2013a), feedback mechanisms Petkova & Maio 2012;, primordial streaming motions , nonstandard cosmologies (Maio et al 2006;Maio & Iannuzzi 2011;Maio 2011;de Souza et al 2013c), high-z luminosity function (Salvaterra et al 2013;Dayal et al 2013), early gamma ray bursts- (Campisi et al 2011;de Souza et al 2011ade Souza et al , 2012Maio et al 2012;Mesler et al 2014) and SNe-host properties (de Souza & Ishida 2010;de Souza et al 2011b;Johnson et al 2013;Whalen et al 2013a,b), Lyα emitters (Jeeson-Daniel et al 2012) and damped Lyα (DLA) system chemical content ) are presented and discussed.…”

Section: Simulationsmentioning

confidence: 99%

Robust PCA and MIC statistics of baryons in early minihaloes

Maio

Biffi

Ciardi

2014

Monthly Notices of the Royal Astronomical Society

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We present a novel approach, based on robust principal components analysis (RPCA) and maximal information coefficient (MIC), to study the redshift dependence of halo baryonic properties. Our data are composed of a set of different physical quantities for primordial minihaloes: dark-matter mass (M dm ), gas mass (M gas ), stellar mass (M star ), molecular fraction (x mol ), metallicity (Z), star formation rate (SFR) and temperature. We find that M dm and M gas are dominant factors for variance, particularly at high redshift. Nonetheless, with the emergence of the first stars and subsequent feedback mechanisms, x mol , SFR and Z start to have a more dominant role. Standard PCA gives three principal components (PCs) capable to explain more than 97 per cent of the data variance at any redshift (two PCs usually accounting for no less than 92 per cent), whilst the first PC from the RPCA analysis explains no less than 84 per cent of the total variance in the entire redshift range (with two PCs explaining 95 per cent anytime). Our analysis also suggests that all the gaseous properties have a stronger correlation with M gas than with M dm , while M gas has a deeper correlation with x mol than with Z or SFR. This indicates the crucial role of gas molecular content to initiate star formation and consequent metal pollution from Population III and Population II/I regimes in primordial galaxies. Finally, a comparison between MIC and Spearman correlation coefficient shows that the former is a more reliable indicator when halo properties are weakly correlated.

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Searching for the first stars with theGaiamission

Cited by 10 publications

References 90 publications

The numerical frontier of the high-redshift Universe

The numerical frontier of the high-redshift Universe

The overlooked potential of Generalized Linear Models in astronomy, I: Binomial regression

Robust PCA and MIC statistics of baryons in early minihaloes

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