scholarly journals Impact of the First Stars to the First Galaxy Formation

2012 ◽  
Vol 8 (S295) ◽  
pp. 21-21
Author(s):  
Ke-Jung Chen ◽  
Myoungwon Jeon ◽  
Thomas Greif ◽  
Volker Bromm ◽  
Alexander Heger
Keyword(s):  
Radiative Transfer ◽  
Galaxy Formation ◽  
Cosmological Simulations ◽  
First Stars ◽  
Stellar Feedback ◽  
Stellar Models ◽  
First Galaxies ◽  
The Impact

AbstractWe present the results from our cosmological simulations of the first stages of galaxy formation. We use Gadget-2 (Springel 2005), modified to include detailed cooling, chemistry, and radiative transfer of primordial gas to study the impact of the first stars on galaxy formation. In contrast to previous work, we apply a realistic treatment of stellar feedback by using updated stellar models for the first stars. In this proceeding, we briefly summarize how stellar feedback from the first stars affects the primordial IGM inside the first galaxies.

scholarly journals The impact of stellar feedback on high-z galaxy populations

2015 ◽  
Vol 11 (S319) ◽  
pp. 26-26
Author(s):  
Michaela Hirschmann ◽  
Gabriella De Lucia
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Large Scale ◽  
Mass Function ◽  
Chemical Enrichment ◽  
Stellar Feedback ◽  
Feedback Scheme ◽  
Galaxy Populations ◽  
Improved Model ◽  
The Impact

AbstractOne major deficiency of state-of-the-art galaxy formation models consists in their inability of capturing the observed galaxy downsizing trend significantly over-estimating the number density of low-mass galaxies, in particular at high redshifts. Employing an enhanced galaxy formation model with a full chemical enrichment scheme (DeLucia et al., 2014), we present an improved model for stellar feedback (based on parametrizations from cosmological zoom simulations), in which strong gas outflows occur due to bursty star formation at high z, while star formation is mainly “quiescent” not causing any significant outflows anymore at low z. Due to the stronger gas outflows at high z, early star formation is strongly delayed towards later times. This helps to sufficiently detach the evolution of galaxy growth from the hiearchical dark matter assembly resulting in a fairly good agreement with the evolution of the observed stellar mass function (SMF, see Fig. 1). With our new feedback scheme, we can also successfully reproduce many other observational constraints, such as the metallicity content, the cold gas fractions or the quiescent galaxy fractions at both low and high redshifts. The resulting new-generation galaxy catalogues (Hirschmann et al., in prep) based on that model are expected to significantly contribute to the interpretation of current and up-coming large-scale surveys (HST, JWST, Euclid). This will, in turn, provide a rapid verification and refinement of our modeling.

scholarly journals Shedding light on high-redshift galaxies with the 21cm signal

2019 ◽  
Vol 15 (S352) ◽  
pp. 69-69
Author(s):  
Anne Hutter
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
First Stars ◽  
High Redshift Galaxies ◽  
Redshift Galaxy ◽  
First Galaxies ◽  
Galaxy Population ◽  
The Impact ◽  
Redshift Galaxies

AbstractReionization represents an important epoch in the history in the Universe, when the first stars and galaxies gradually ionize the neutral hydrogen in the intergalactic medium (IGM). Understanding the nature of the ionizing sources, the associated ionization of the IGM, and its impact on subsequent structure formation and galaxy evolution by means of radiative feedback effects, represent key outstanding questions in current astrophysics. High-redshift galaxy observations and simulations have significantly extended our knowledge on the nature of high-redshift galaxies. However, essential properties such as the escape fraction of ionizing photons from galaxies into the IGM and their dependency on galactic properties remain essentially unknown, but determine significantly the distribution and time evolution of the ionized regions during reionization. Analyzing this ionization topology by means of the neutral hydrogen sensitive 21cm signal with radio interferometers such as SKA offers a complementary and unique opportunity to determine the nature of these first galaxies. I will show results from a self-consistent semi-numerical model of galaxy evolution and reionization, and discuss the potential of inferring galactic properties with the 21cm signal as well as the impact of reionization on the high-redshift galaxy population and its evolution.

Stellar Feedback and Galaxy Formation

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Computer Simulations ◽  
Galaxy Formation ◽  
Second Generation ◽  
Feedback Effects ◽  
First Stars ◽  
Stellar Feedback

This chapter studies radiative, mechanical, and chemical feedback in the earliest gaseous clouds, taking up the thread of discussion in the previous chapter to consider the influences placed on the formation of second-generation stars. While the feedback effects are sufficiently complex that a complete description of them is well beyond the capabilities of present-day computer simulations, the general principles that underlie them are well known. Therefore, the chapter focuses on these principles and then briefly sketches the global picture. Feedback is important in all galaxies, and many of the principles that are discussed in this chapter apply on a much wider scale than just the first stars and galaxies.

The Fate of the First Galaxies. I. Self‐consistent Cosmological Simulations with Radiative Transfer

2002 ◽  
Vol 575 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Massimo Ricotti ◽  
Nickolay Y. Gnedin ◽  
J. Michael Shull
Keyword(s):  
Radiative Transfer ◽  
Cosmological Simulations ◽  
Self Consistent ◽  
First Galaxies

scholarly journals Magnetogenesis around the first galaxies: the impact of different field seeding processes on galaxy formation

2021 ◽  
Author(s):  
Enrico Garaldi ◽  
Rüdiger Pakmor ◽  
Volker Springel
Keyword(s):  
Magnetic Fields ◽  
Galaxy Formation ◽  
Ad Hoc ◽  
High Redshift ◽  
Ionization Fronts ◽  
Seed Field ◽  
Biermann Battery ◽  
First Galaxies ◽  
High Redshift Universe ◽  
The Impact

Abstract We study the evolution of magnetic fields generated by charge segregation ahead of ionization fronts during the Epoch of Reionization, and their effects on galaxy formation. We compare this magnetic seeding process with the Biermann battery, injection from supernovae, and an imposed seed field at redshift z ≳ 127. Using a suite of self-consistent cosmological and zoom-in simulations based on the Auriga galaxy-formation model, we determine that all mechanisms produce galactic magnetic fields that equally affect galaxy formation, and are nearly indistinguishable at z ≲ 1.5. The former is compatible with observed values, while the latter is correlated with the gas metallicity below a seed-dependent redshift. Low-density gas and haloes below a seed-dependent mass threshold retain memory of the initial magnetic field. We produce synthetic Faraday rotation measure maps, showing that they have the potential to constrain the seeding process, although current observations are not yet sensitive enough. Our results imply that the ad-hoc assumption of a primordial seed field – widely used in galaxy formation simulations but of uncertain physical origin – can be replaced by physically-motivated mechanisms for magnetogenesis with negligible impact on galactic properties. Additionally, magnetic fields generated ahead of ionization fronts appear very similar but weaker than those produced by the Biermann battery. Hence, in a realistic scenario where both mechanisms are active, the former will be negligible compared to the latter. Finally, our results highlight that the high-redshift Universe is a fruitful testing ground for our understanding of magnetic fields generation.

scholarly journals Early galaxy formation and its large-scale effects

2019 ◽  
Vol 15 (S352) ◽  
pp. 43-43
Author(s):  
Pratika Dayal
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Scale Effects ◽  
High Redshift ◽  
Early Galaxies ◽  
First Galaxies ◽  
The Impact ◽  
Early Galaxy

AbstractGalaxy formation in the first billion years mark a time of great upheaval in the history of the Universe: the first galaxies started both the ‘metal age’ as well as the era of cosmic reionization. I will start by reviewing the dust production mechanisms and dust masses for high-redshift galaxies which will be revolutionized in the ALMA era. I will then show how the JWST will be an invaluable experiment to shed light on the impact of reionization feedback on early galaxy formation. As we look forward towards the era of 21cm cosmology, I will highlight the crucial and urgent synergies required between 21cm facilities (such as the SKA) and galaxy experiments (JWST, E-ELT and Subaru to name a few) to understand the physics of the epoch of reionization that remains a crucial frontier in the field of astrophysics and physical cosmology. Time permitting, I will try to give a flavour of how the assembly of early galaxies, accessible with the forthcoming JWST, can provide a powerful testbed for Dark Matter models beyond ‘Cold Dark Matter’.

scholarly journals Cosmological simulations of the same spiral galaxy: the impact of baryonic physics

2020 ◽  
Vol 501 (1) ◽  
pp. 62-77
Author(s):  
A Nuñez-Castiñeyra ◽  
E Nezri ◽  
J Devriendt ◽  
R Teyssier
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Cosmological Simulations ◽  
Star Forming ◽  
Small Scales ◽  
The Impact

ABSTRACT The interplay of star formation (SF) and supernova (SN) feedback in galaxy formation is a key element for understanding galaxy evolution. Since these processes occur at small scales, it is necessary to have sub-grid models that recover their evolution and environmental effects at the scales reached by cosmological simulations. In this work, we present the results of the Mochima simulation, where we simulate the same spiral galaxy inhabiting a Milky Way (MW) size halo in a cosmological environment changing the sub-grid models for SN feedback and SF. We test combinations of the Schmidt law and a multifreefall based SF with delayed cooling feedback or mechanical feedback. We reach a resolution of 35 pc in a zoom-in box of 36 Mpc. For this, we use the code $\rm{\small RAMSES}$ with the implementation of gas turbulence in time and trace the local hydrodynamical features of the star-forming gas. Finally, we compare the galaxies at redshift 0 with global and interstellar medium observations in the MW and local spiral galaxies. The simulations show successful comparisons with observations. Nevertheless, diverse galactic morphologies are obtained from different numerical implementations. We highlight the importance of detailed modelling of the SF and feedback processes, especially for simulations with a resolution that start to reach scales relevant for molecular cloud physics. Future improvements could alleviate the degeneracies exhibited in our simulated galaxies under different sub-grid models.

Pop III Supernova Feedback on the Formation of the First Galaxies

2019 ◽  
Vol 15 (S341) ◽  
pp. 253-256 ◽  
Author(s):  
Li-Hsin Chen ◽  
Ke-Jung Chen
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Adaptive Mesh Refinement ◽  
Initial Conditions ◽  
Adaptive Mesh ◽  
Building Blocks ◽  
Dark Matter Halos ◽  
First Stars ◽  
Stellar Feedback ◽  
First Galaxies

AbstractModern cosmological simulations suggest that the hierarchical assembly of dark matter halos provided the gravitational wells that allowed the primordial gases to form stars and galaxies inside them. The first galaxies comprised of the first systems of stars gravitationally bound in dark matter halos are naturally recognized as the building blocks of early Universe. To understand the formation of the first galaxies, we use an adaptive mesh refinement (AMR) cosmological code, Enzo to simulate the formation and evolution of the first galaxies. We first model an isolated galaxy by considering much microphysics such as star formation, stellar feedback, and primordial gas cooling. To examine the effect of Pop III stellar feedback to the first galaxy formation, we adjust the initial temperature, density distribution and metallicity distributions by assuming different IMFs of the first stars. Our results suggest that star formation in the first galaxies is sensitive to the initial conditions of Pop III supernovae and their remnants. Our study can help to correlate the populations of the first stars and supernovae to star formation inside these first galaxies which may be soon observed by the (James Webb Space Telescope JWST).

scholarly journals Supermassive black holes in cosmological simulations I: MBH − M⋆ relation and black hole mass function

2021 ◽  
Author(s):  
Mélanie Habouzit ◽  
Yuan Li ◽  
Rachel S Somerville ◽  
Shy Genel ◽  
Annalisa Pillepich ◽  
...  
Keyword(s):  
Black Holes ◽  
Time Evolution ◽  
Galaxy Formation ◽  
Large Scale ◽  
Mass Function ◽  
Supermassive Black Holes ◽  
High Mass ◽  
Cosmological Simulations ◽  
Low Mass ◽  
The Impact

Abstract The past decade has seen significant progress in understanding galaxy formation and evolution using large-scale cosmological simulations. While these simulations produce galaxies in overall good agreement with observations, they employ different sub-grid models for galaxies and supermassive black holes (BHs). We investigate the impact of the sub-grid models on the BH mass properties of the Illustris, TNG100, TNG300, Horizon-AGN, EAGLE, and SIMBA simulations, focusing on the MBH − M⋆ relation and the BH mass function. All simulations predict tight MBH − M⋆ relations, and struggle to produce BHs of $M_{\rm BH}\leqslant 10^{7.5}\, \rm M_{\odot }$ in galaxies of $M_{\star }\sim 10^{10.5}-10^{11.5}\, \rm M_{\odot }$. While the time evolution of the mean MBH − M⋆ relation is mild ($\rm \Delta M_{\rm BH}\leqslant 1\, dex$ for 0 ≤ z ≤ 5) for all the simulations, its linearity (shape) and normalization varies from simulation to simulation. The strength of SN feedback has a large impact on the linearity and time evolution for $M_{\star }\leqslant 10^{10.5}\, \rm M_{\odot }$. We find that the low-mass end is a good discriminant of the simulation models, and highlights the need for new observational constraints. At the high-mass end, strong AGN feedback can suppress the time evolution of the relation normalization. Compared with observations of the local Universe, we find an excess of BHs with $M_{\rm BH}\geqslant 10^{9}\, \rm M_{\odot }$ in most of the simulations. The BH mass function is dominated by efficiently accreting BHs (log10 fEdd ≥ −2) at high redshifts, and transitions progressively from the high-mass to the low-mass end to be governed by inactive BHs. The transition time and the contribution of active BHs are different among the simulations, and can be used to evaluate models against observations.

scholarly journals Supernovae and the Galactic Ecosystem

2013 ◽  
Vol 9 (S296) ◽  
pp. 273-281 ◽  
Author(s):  
Q. Daniel Wang
Keyword(s):  
Galaxy Formation ◽  
Supernova Remnants ◽  
Theoretical Work ◽  
Low Density ◽  
Feedback Process ◽  
Hot Gas ◽  
Stellar Feedback ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
The Impact

AbstractSupernovae are the dominant source of stellar feedback, which plays an important role in regulating galaxy formation and evolution. While this feedback process is still quite uncertain, it is probably not due to individual supernova remnants as commonly observed. Most supernovae likely take place in low-density, hot gaseous environments, such as superbubbles and galactic bulges, and typically produce no long-lasting bright remnants. I review recent observational and theoretical work on the impact of such supernovae on galaxy ecosystems, particularly on hot gas in superbubbles and galactic spheroids.

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