Growth of First Galaxies: Impacts of Star Formation and Stellar Feedback

Yajima, Hidenobu; Nagamine, Kentaro; Zhu, Qirong; Khochfar, Sadegh; Vecchia, Claudio Dalla

doi:10.3847/1538-4357/aa82b5

Cited by 41 publications

(37 citation statements)

References 96 publications

(148 reference statements)

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“…These studies reveal that stellar and supernova (SN) feedback are crucial for galaxy evolution. In particular, Yajima et al (2017a) studied galaxy evolution in massive halos (M h 10 11 M ) at z 6 using cosmological hydrodynamic simulations, and found that the star formation occurs intermittently due to SN feedback and gas accretion (see also, Kimm & Cen 2014). However, the radiative properties associated with the bursty star-formation history are not fully understood yet.…”

Section: Introductionmentioning

confidence: 99%

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Arata

Yajima

Nagamine

et al. 2019

Monthly Notices of the Royal Astronomical Society

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ABSTRACT Recent observations have successfully detected UV-bright and infrared-bright galaxies in the epoch of reionization. However, the origin of their radiative properties has not been understood yet. Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present predictions of multiwavelength radiative properties of the first galaxies at z ∼ 6–15. Using zoom-in initial conditions, we investigate three massive galaxies and their satellites in different environment and halo masses at z = 6: $M_{\rm h}= 2.4\times 10^{10}\,$, $1.6\times 10^{11}\, $, and $0.7\times 10^{12}\, {\rm M_{\odot }}$. We find that most of the gas and dust are ejected from star-forming regions by supernova feedback, which allows the UV photons to escape. We show that the peak of the spectral energy distribution (SED) rapidly changes between UV and infrared wavelengths on a time-scale of ∼ 100 Myr due to intermittent star formation and feedback, and the escape fraction of UV photons fluctuates in the range of 0.2–0.8 at z < 10 with a time-averaged value of 0.3. When dusty gas covers the star-forming regions, the galaxies become bright in the observed-frame sub-millimeter wavelengths. We predict the detectability of high-z galaxies with the Atacama Large Millimeter Array (ALMA). For a sensitivity limit of $0.1\, {\rm mJy}$ at $850\, {\rm \mu m}$, the detection probability of galaxies in haloes $M_{\rm h}\gtrsim 10^{11}\, \, {\rm M_{\odot }}$ at z ≲ 7 exceeds fifty per cent. We argue that supernova feedback can produce the observed diversity of SEDs for high-z galaxies.

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Section: Introductionmentioning

confidence: 99%

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Arata

Yajima

Nagamine

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…The focus has instead been on theoretical studies to investigate how the first galaxies were assembled, and how the first generation of stars played a role in shaping the conditions for their formation (e.g. Maio et al 2010;Wise et al 2012;Johnson et al 2013;Xu et al 2016;Yajima et al 2017;Kimm et al 2017;Wilkins et al 2017;Griffen et al 2018;Ma et al 2018;Jaacks et al 2018a). Owing to their small size (r vir = 1 − 3 kpc) and rather short evolutionary timescales (<1 Gyr), the first galaxies are an ideal target for numerical studies, allowing simulators, in principle, to build up a galaxy in an ab-initio fashion.…”

Section: Introductionmentioning

confidence: 99%

Signature of the first galaxies in JWST deep field observations

Jeon

2019

Monthly Notices of the Royal Astronomical Society

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We examine the assembly process and the observability of a first galaxy (M vir ≈ 10 9 M at z ≈ 8) with cosmological zoom-in, hydrodynamic simulations, including the radiative, mechanical, and chemical feedback exerted by the first generations of stars. To assess the detectability of such dwarf systems with the upcoming James Webb Space Telescope (JWST), we construct the spectral energy distribution for the simulated galaxy in a post-processing fashion. We find that while the non-ionizing UV continuum emitted by the simulated galaxy is expected to be below the JWST detection limit, the galaxy might be detectable using its nebular emission, specifically in the Hα recombination line. This requires that the galaxy experiences an active starburst with a star formation rate of M * 0.1 M yr −1 at z ≈ 9. Due to the bursty nature of star formation in the first galaxies, the time interval for strong nebular emission is short, less than 2 − 3 Myr. The probability of capturing such primordial dwarf galaxies during the observable part of their duty cycle is thus low, resulting in number densities of order one source in a single pointing with MIRI onboard the JWST, for very deep exposures. Gravitational lensing, however, will boost their observability beyond this conservative baseline. The first sources of light will thus come firmly within our reach.

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“…For example, Susa & Umemura (2004) showed that the morphology of galaxies could change significantly in different UV background fields due to the suppression of star formation. Okamoto et al (2008) indi- cated that the UV background could reduce the cosmic star formation history significantly because of the suppression of star formation in dwarf galaxies (see also, Hasegawa & Semelin 2013;Yajima et al 2017). These previous works focused on the photo-evaporation effects of gas by the Lymancontinuum photons.…”

Section: Impact Of Hydrogen Moleculesmentioning

confidence: 99%

“…Note that the high resolution with < 1 pc is required to follow the cloud formation via thermal instability as we discuss in the Appendix. Current cosmological simulations are still difficult to resolve such small scales (e.g., Kim et al 2017;Yajima et al 2017). In addition, the massive clouds could form within several Myr, while the mass inflow to the galactic center occurs over the galaxy dynamical time > 10 Myr.…”

Section: Formation Of Cold Gas Clouds Withmentioning

confidence: 99%

“…The formation and evolution of high-redshift dwarf E-mail: arata@vega.ess.sci.osaka-u.ac.jp galaxies are significantly affected by star formation and stellar feedback, because the gas in these galaxies can easily be pushed out from the shallow gravitational potential well of the low-mass haloes due to feedback (e.g., Wise et al 2012;Johnson et al 2013;Hasegawa & Semelin 2013;Hopkins et al 2014;Kimm & Cen 2014;Yajima et al 2017). Star formation occurs in cold gas clumps in galaxies.…”

Section: Introductionmentioning

confidence: 99%

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Gas clump formation via thermal instability in high-redshift dwarf galaxy mergers

Arata

Yajima

Nagamine

2018

Monthly Notices of the Royal Astronomical Society

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Star formation in high-redshift dwarf galaxies is a key to understand early galaxy evolution in the early Universe. Using the three-dimensional hydrodynamics code GIZMO, we study the formation mechanism of cold, high-density gas clouds in interacting dwarf galaxies with halo masses of ∼ 3 × 10 7 M , which are likely to be the formation sites of early star clusters. Our simulations can resolve both the structure of interstellar medium on small scales of 0.1 pc and the galactic disk simultaneously. We find that the cold gas clouds form in the post-shock region via thermal instability due to metalline cooling, when the cooling time is shorter than the galactic dynamical time. The mass function of cold clouds shows almost a power-law initially with an upper limit of thermally unstable scale. We find that some clouds merge into more massive ones with 10 4 M within ∼ 2 Myr. Only the massive cold clouds with 10 3 M can keep collapsing due to gravitational instability, resulting in the formation of star clusters. In addition, we investigate the dependence of cloud mass function on metallicity and H 2 abundance, and show that the cases with low metallicities ( 10 −2 Z ) or high H 2 abundance ( 10 −3 ) cannot form massive cold clouds with 10 3 M .

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Growth of First Galaxies: Impacts of Star Formation and Stellar Feedback

Cited by 41 publications

References 96 publications

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Signature of the first galaxies in JWST deep field observations

Gas clump formation via thermal instability in high-redshift dwarf galaxy mergers

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