scholarly journals UV regulated star formation in high-redshift galaxies

2019 ◽  
Vol 490 (2) ◽  
pp. 2706-2716 ◽  
Author(s):  
Muhammad A Latif ◽  
Sadegh Khochfar
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Background Radiation ◽  
High Redshift ◽  
Three Dimensional ◽  
Background Level ◽  
Reaction Rates ◽  
Big Bang ◽  
Dense Gas ◽  
First Galaxies

ABSTRACT The first galaxies forming a few hundred million years after the big bang are the key drivers of cosmic evolution and ideal laboratories to study theories of galaxy formation. We here study the role of UV radiation in suppressing star formation in primordial galaxies by destroying molecular hydrogen, the main coolant in primordial gas, and provide estimates of cold dense gas at the onset of star formation. To accomplish this goal, we perform three-dimensional cosmological simulations of minihaloes in different environments forming at z ∼ 25 by varying strength of background UV flux below the Lyman limit between 0.01–1000 in units of $\rm J_{21}=10^{-21}\, erg \,cm^{-2} \,s^{-1} \,Hz^{-1} \,sr^{-1}$. Particularly, we include photodetachment of $\rm H^-$, the self-shielding of $\rm H_2$, which both were neglected in previous studies and use updated reaction rates. Our results show that depending on the background level $\rm H_2$ formation is suppressed, delaying gravitational collapse until haloes reach the atomic cooling limit. We find that the formation of cold dense molecular gas and subsequently star formation gets delayed by 100–230 Myr depending on the level of the background radiation and the growth history of the dark matter haloes. The fraction of dense self-shielded gas is a strong function of the background flux and exponentially declines with the strength of incident UV flux above $\rm J_{21} \ge 1$. We find that taking into account $\rm H_2$ self-shielding is crucial for accurately estimating the amount of cold dense gas available for star formation.

scholarly journals Intense starbursts at z~5: first significant stellar mass assembly in the progenitors of present-day spheroids

2007 ◽  
Vol 3 (S245) ◽  
pp. 471-476
Author(s):  
Aprajita Verma ◽  
Matthew Lehnert ◽  
Natascha Förster Schreiber ◽  
Malcolm Bremer ◽  
Laura Douglas
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Large Scale ◽  
Star Formation Rate ◽  
Mass Density ◽  
High Redshift ◽  
Formation Rate ◽  
Big Bang ◽  
Stellar Mass ◽  
Mass Assembly

AbstractHigh redshift galaxies play a key role in our developing understanding of galaxy formation and evolution. Since such galaxies are being studied within a Gyr of the big bang, they provide a unique probe of the physics of one of the first generations of large-scale star-formation. We have performed a complete statistical study of the physical properties of a robust sample of z~5 UV luminous galaxies selected using the Lyman-break technique. The characteristic properties of this sample differ from LBGs at z~3 of comparable luminosity in that they are a factor of ten less massive (~few×109 M⊙) and the majority (~70%) are considerably younger (<100Myr). Our results support no more than a modest decline in the global star formation rate density at high redshifts and suggest that ~1% of the stellar mass density of the universe had already assembled at z~5. The constraint derived for the latter is affected by their young ages and short duty cycles which imply existing z~5 LBG samples may be highly incomplete. These intense starbursts have high unobscured star formation rate surface densities (~100s M⊙ yr−1 kpc−2), suggesting they drive outflows and winds that enrich the intra- and inter-galactic media with metals. These properties imply that the majority of z~5 LBGs are in formation meaning that most of their star-formation has likely occurred during the last few crossing times. They are experiencing their first (few) generations of large-scale star formation and are accumulating their first significant stellar mass. As such, z~5 LBGs are the likely progenitors of the spheroidal components of present-day massive galaxies (supported by their high stellar mass surface densities and their core phase-space densities).

scholarly journals EDGE: a new approach to suppressing numerical diffusion in adaptive mesh simulations of galaxy formation

2020 ◽  
Vol 501 (2) ◽  
pp. 1755-1765
Author(s):  
Andrew Pontzen ◽  
Martin P Rey ◽  
Corentin Cadiou ◽  
Oscar Agertz ◽  
Romain Teyssier ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Initial Conditions ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Morphological Structure ◽  
Adaptive Mesh ◽  
Numerical Diffusion

ABSTRACT We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the ‘EDGE’ project. The target galaxy has a maximum circular velocity of $21\, \mathrm{km}\, \mathrm{s}^{-1}$ but evolves in a region that is moving at up to $90\, \mathrm{km}\, \mathrm{s}^{-1}$ relative to the hydrodynamic grid. In the absence of any mitigation, diffusion softens the filaments feeding our galaxy. As a result, gas is unphysically held in the circumgalactic medium around the galaxy for $320\, \mathrm{Myr}$, delaying the onset of star formation until cooling and collapse eventually triggers an initial starburst at z = 9. Using genetic modification, we produce ‘velocity-zeroed’ initial conditions in which the grid-relative streaming is strongly suppressed; by design, the change does not significantly modify the large-scale structure or dark matter accretion history. The resulting simulation recovers a more physical, gradual onset of star formation starting at z = 17. While the final stellar masses are nearly consistent ($4.8 \times 10^6\, \mathrm{M}_{\odot }$ and $4.4\times 10^6\, \mathrm{M}_{\odot }$ for unmodified and velocity-zeroed, respectively), the dynamical and morphological structure of the z = 0 dwarf galaxies are markedly different due to the contrasting histories. Our approach to diffusion suppression is suitable for any AMR zoom cosmological galaxy formation simulations, and is especially recommended for those of small galaxies at high redshift.

scholarly journals Quasi-equilibrium models of high-redshift disc galaxy evolution

2020 ◽  
Vol 500 (3) ◽  
pp. 3394-3412
Author(s):  
Steven R Furlanetto
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Formation Rate ◽  
New Physics ◽  
Small Scale ◽  
Quasi Equilibrium ◽  
Mass Relation ◽  
Disc Galaxy

ABSTRACT In recent years, simple models of galaxy formation have been shown to provide reasonably good matches to available data on high-redshift luminosity functions. However, these prescriptions are primarily phenomenological, with only crude connections to the physics of galaxy evolution. Here, we introduce a set of galaxy models that are based on a simple physical framework but incorporate more sophisticated models of feedback, star formation, and other processes. We apply these models to the high-redshift regime, showing that most of the generic predictions of the simplest models remain valid. In particular, the stellar mass–halo mass relation depends almost entirely on the physics of feedback (and is thus independent of the details of small-scale star formation) and the specific star formation rate is a simple multiple of the cosmological accretion rate. We also show that, in contrast, the galaxy’s gas mass is sensitive to the physics of star formation, although the inclusion of feedback-driven star formation laws significantly changes the naive expectations. While these models are far from detailed enough to describe every aspect of galaxy formation, they inform our understanding of galaxy formation by illustrating several generic aspects of that process, and they provide a physically grounded basis for extrapolating predictions to faint galaxies and high redshifts currently out of reach of observations. If observations show violations from these simple trends, they would indicate new physics occurring inside the earliest generations of galaxies.

Extreme variations in star formation activity in the first galaxies

2019 ◽  
Vol 15 (S341) ◽  
pp. 226-230
Author(s):  
Christian Binggeli ◽  
Erik Zackrisson ◽  
Xiangcheng Ma ◽  
Akio K. Inoue ◽  
Anton Vikaeus ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
High Redshift ◽  
Formation Rate ◽  
High Redshift Galaxies ◽  
James Webb Space Telescope ◽  
Star Formation Activity ◽  
The Galaxy ◽  
First Galaxies ◽  
Star Formation Histories

AbstractRecently, spectroscopic detections of O[III] 88 μm and Ly-α emission lines from the z ≍ 9.1 galaxy MACS1149-JD1 have been presented, and with these, some interesting properties of this galaxy were uncovered. One such property is that MACS1149-JD1 exhibits a significant Balmer break at around rest-frame 4000 Å, which may indicate that the galaxy has experienced large variations in star formation rate prior to z ∼ 9, with a rather long period of low star formation activity. While some simulations predict large variations in star formation activity in high-redshift galaxies, it is unclear whether the simulations can reproduce the kind of variations seen in MACS1149-JD1. Here, we utilize synthetic spectra of simulated galaxies from two simulation suites in order to study to what extent these can accurately reproduce the spectral features (specifically the Balmer break) observed in MACS1149-JD1. We show that while the simulations used in this study produce galaxies with varying star formation histories, galaxies such as MACS1149-JD1 would be very rare in the simulations. In principle, future observations with the James Webb Space Telescope may tell us if MACS1149-JD1 represents something rare, or if such galaxies are more common than predicted by current simulations.

scholarly journals Dark-ages reionization and galaxy formation simulation – XIII. AGN quenching of high-redshift star formation in ZF-COSMOS-20115

2017 ◽  
Vol 471 (4) ◽  
pp. 4345-4354 ◽  
Author(s):  
Yuxiang Qin ◽  
Simon J. Mutch ◽  
Alan R. Duffy ◽  
Paul M. Geil ◽  
Gregory B. Poole ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
High Redshift ◽  
Dark Ages

scholarly journals A Simulation of Galaxy Formation by Radiation-SPH

2003 ◽  
Vol 208 ◽  
pp. 323-330
Author(s):  
Hajime Susa ◽  
Masayuki Umemura
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Galaxy Formation ◽  
Background Radiation ◽  
Early Type ◽  
Late Type ◽  
Lower Redshift

We investigate galaxy formation with Radiation-SPH simulations in order to find the effects of ultraviolet background radiation field on the star formation in the forming galaxies. We find the ultraviolet background radiation field can delay the star formation in protogalactic clouds, especially at low redshift (z < 2). This result suggests that galaxies formed at lower redshift tend to be late type galaxies, and early type galaxies tend to be formed at higher redshift.

scholarly journals Spatially resolving the relics: The inferring the physics driving the quenching of massive galaxies from kinematics at z ∼ 1 and beyond

2019 ◽  
Vol 15 (S352) ◽  
pp. 267-267
Author(s):  
Rachel Bezanson
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Spectroscopic Studies ◽  
Gas Reservoirs ◽  
Massive Galaxies ◽  
Spatially Resolved ◽  
Galaxy Formation And Evolution ◽  
Ordered Motion

AbstractToday's massive elliptical galaxies are primarily red-and-dead, dispersion supported ellipticals. The physical process(es) driving the shutdown or ‘quenching’ of star formation in these galaxies remains one of the least understood aspects of galaxy formation and evolution. Although today's spiral and elliptical galaxies exhibit a clear bimodality in their structures, kinematics, and stellar populations, it may be that the quenching and structural transformation do no occur simultaneously. In this talk I will present evidence that early quiescent galaxies, observed much closer to their quenching epoch at z ∼ 1, retain significant rotational support (∼ twice as much as local ellipticals). This suggests that the mechanisms responsible for shutting down star formation do not also have to destroy ordered motion in massive galaxies; the increased dispersion support could occur subsequently via hierarchical growth and minor merging. I will discuss this evidence in conjunction with recent ALMA studies of the dramatic range in molecular gas reservoirs of recently quenched high redshift galaxies to constrain quenching models. Finally, I will discuss prospects for extending spatially resolved spectroscopic studies of galaxies immediately following quenching with JWST and eventually 30-m class telescopes.

scholarly journals Panchromatic study of the first galaxies with large ALMA programs

2019 ◽  
Vol 15 (S341) ◽  
pp. 12-16 ◽  
Author(s):  
A. Faisst ◽  
M. Béthermin ◽  
P. Capak ◽  
P. Cassata ◽  
O. Le Fèvre ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Optical Emission ◽  
Far Infrared ◽  
Photometric Redshifts ◽  
Galaxy Formation And Evolution ◽  
Major Player ◽  
Imaging And Spectroscopy ◽  
First Galaxies ◽  
Stellar Masses

AbstractThanks to deep optical to near-IR imaging and spectroscopy, significant progress is made in characterizing the rest-frame UV to optical properties of galaxies in the early universe (z > 4. Surveys with Hubble, Spitzer, and ground-based facilities (Keck, Subaru, and VLT) provide spectroscopic and photometric redshifts, measurements of the spatial structure, stellar masses, and optical emission lines for large samples of galaxies. Recently, the Atacama Large (Sub) Millimeter Array (ALMA) has become a major player in pushing studies of high redshift galaxies to far-infrared wavelengths, hence making panchromatic surveys over many orders of frequencies possible. While past studies focused mostly on bright sub-millimeter galaxies, the sensitivity of ALMA now enables surveys like ALPINE, which focuses on measuring the gas and dust properties of a large sample of normal main-sequence galaxies at z > 4. Combining observations across different wavelengths into a single, panchromatic picture of galaxy formation and evolution is currently and in the future an important focus of the astronomical community.

Panchromatic study of the first galaxies in cosmological simulations

2019 ◽  
Vol 15 (S341) ◽  
pp. 240-244
Author(s):  
Hidenobu Yajima ◽  
Shohei Arata ◽  
Makito Abe ◽  
Kentaro Nagamine
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
High Redshift ◽  
Radiative Properties ◽  
Massive Galaxies ◽  
Star Forming ◽  
Lyman Alpha ◽  
Radiation Properties ◽  
Multi Wavelength ◽  
First Galaxies

AbstractRecent discoveries of high-redshift galaxies have revealed the diversity of their physical properties, from normal star-forming galaxies to starburst galaxies. To understand the properties of these observed galaxies, it is crucial to understand the star formation (SF) history, and the radiation properties associated with the SF activity. Here we present the results of cosmological hydrodynamic simulations with zoom-in initial conditions, and show the formation of the first galaxies and their evolution towards observable galaxies at z = 6. In addition, we show their multi-wavelength radiative properties. We find that star formation occurs intermittently due to supernova (SN) feedback at z > 10, and their radiation properties rapidly change with time. We suggest that the first galaxies are bright at UV wavelengths just after the starburst phase, and become extended Lyman-alpha sources. We also show that massive galaxies cause dusty starburst and become bright at infrared wavelengths.

scholarly journals Towards a multi-scale understanding of the gas-star formation cycle in the Central Molecular Zone

2016 ◽  
Vol 11 (S322) ◽  
pp. 64-74
Author(s):  
J. M. Diederik Kruijssen
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
High Redshift ◽  
Three Dimensional ◽  
Orbital Dynamics ◽  
Molecular Gas ◽  
Stellar Clusters ◽  
High Redshift Galaxies ◽  
Multi Scale ◽  
The Galaxy

AbstractThe Central Molecular Zone (CMZ, the central 500 pc of the Milky Way) contains the largest reservoir of high-density molecular gas in the Galaxy, but forms stars at a rate 10–100 times below commonly-used star formation relations. We discuss recent efforts in understanding how the nearest galactic nucleus forms its stars. The latest models of the gas inflow, star formation, and feedback duty cycle reproduce the main observable features of the CMZ, showing that star formation is episodic and that the CMZ currently resides at a star formation minimum. Using orbital modelling, we derive the three-dimensional geometry of the CMZ and show how the orbital dynamics and the star formation potential of the gas are closely coupled. We discuss how this coupling reveals the physics of star formation and feedback under the conditions seen in high-redshift galaxies, and promotes the formation of the densest stellar clusters in the Galaxy.

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