Topic
Dark Ages
About: Dark Ages is a research topic. Over the lifetime, 312 publications have been published within this topic receiving 8784 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: In this article, the authors simulate a plausible cosmological model in considerable physical and numerical detail through the successive phases of reheating (at 10 z 20) and reionization at z ≈ 7.4.
Abstract: We simulate a plausible cosmological model in considerable physical and numerical detail through the successive phases of reheating (at 10 z 20) and reionization at z ≈ 7. We assume an efficiency of high-mass star formation appropriate to leave the universe, after it becomes transparent, with an ionizing background J21 ≈ 0.4 (at z = 4), near (and perhaps slightly below) the observed value. Since the same stars produce the ionizing radiation and the first generation of heavy elements, a mean metallicity of Z/Z☉ ~ 1/200 is produced in this early phase, but there is a large variation about this mean, with the high density regions having Z/Z☉ ≈ 1/30 and the low density regions (or the Lyα forest with NH I 1013.5 cm2) having essentially no metals. When it occurs, reionization is very rapid (phase change-like), which will leave a signature that may be detectable by very large area meter-wavelength radio instruments. Also, the background UV radiation field will show a sharp drop of ~10-3 from 1 to 4 ryd because of absorption edges. The simulated volume is too small to form L* galaxies, but the smaller objects that are found in the simulation obey the Faber-Jackson relation. In order to explore theoretically this domain of "the end of the dark ages" quantitatively, numerical simulations must have a mass resolution of the order of 104.5 M☉ in baryons, have high spatial resolution (1 kpc) to resolve strong clumping, and allow for detailed and accurate treatment of both the radiation field and atomic/molecular physics.
661 citations
TL;DR: In this paper, the authors consider particle decays during the cosmic dark ages with two aims: (1) to explain the high optical depth reported by the Wilkinson Microwave Anisotropy Probe (WMAP), and (2) to provide new constraints to the parameter space for decaying particles.
Abstract: We consider particle decays during the cosmic dark ages with two aims: (1) to explain the high optical depth reported by the Wilkinson Microwave Anisotropy Probe (WMAP), and (2) to provide new constraints to the parameter space for decaying particles. We delineate the decay channels in which most of the decay energy ionizes and heats the intergalactic medium gas [and thus affects the cosmic microwave background (CMB)], and those in which most of the energy is carried away—e.g. photons with energies 100 keV<~E<~1 TeV—and thus appears as a contribution to diffuse x-ray and gamma-ray backgrounds. The new constraints to the decay-particle parameters from the CMB power spectrum thus complement those from the cosmic x-ray and gamma-ray backgrounds. Although decaying particles can indeed produce an optical depth consistent with that reported by WMAP, in so doing they produce new fluctuations in the CMB temperature and polarization power spectra. For decay lifetimes less than the age of the Universe, the induced power spectra generally violate current constraints, while the power spectra are usually consistent if the lifetime is longer than the age of the Universe.
523 citations
[...]
TL;DR: In this paper, the authors review the current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang, and derive the signature of galaxies to be observed with upcoming or planned next-generation facilities, such as the James Webb Space Telescope or Atacama Large Millimeter Array.
Abstract: We review our current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang. Modern large telescopes discovered galaxies at redshifts greater than seven, whereas theoretical studies have just reached the degree of sophistication necessary to make meaningful predictions. A crucial ingredient is the feedback exerted by the first generation of stars, through UV radiation, supernova blast waves, and chemical enrichment. The key goal is to derive the signature of the first galaxies to be observed with upcoming or planned next-generation facilities, such as the James Webb Space Telescope or Atacama Large Millimeter Array. From the observational side, ongoing deep-field searches for very high-redshift galaxies begin to provide us with empirical constraints on the nature of the first galaxies.
456 citations
[...]
TL;DR: In this paper, the authors review the current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang, and derive the signature of galaxies to be observed with upcoming or planned next-generation facilities, such as the James Webb Space Telescope or Atacama Large Millimeter Array.
Abstract: We review our current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang. Modern large telescopes discovered galaxies at redshifts greater than seven, whereas theoretical studies have just reached the degree of sophistication necessary to make meaningful predictions. A crucial ingredient is the feedback exerted by the first generation of stars, through UV radiation, supernova blast waves, and chemical enrichment. The key goal is to derive the signature of the first galaxies to be observed with upcoming or planned next-generation facilities, such as the James Webb Space Telescope or Atacama Large Millimeter Array. From the observational side, ongoing deep-field searches for very high-redshift galaxies begin to provide us with empirical constraints on the nature of the first galaxies.
406 citations
TL;DR: In this paper, the authors investigated the physical mechanisms that make 21-cm radiation from neutral intergalactic medium (IGM) at high redshift detectable against the cosmic microwave background, including Ly_alpha coupling of the hydrogen spin temperature to the kinetic temperature of the gas and preheating of the IGM by the first generation of stars and quasars.
Abstract: The emission of 21-cm radiation from a neutral intergalactic medium (IGM) at high redshift is discussed in connection with the thermal and ionization history of the universe. The physical mechanisms that make such radiation detectable against the cosmic microwave background include Ly_alpha coupling of the hydrogen spin temperature to the kinetic temperature of the gas and preheating of the IGM by the first generation of stars and quasars. Three different signatures are investigated in detail: (a) the fluctuations in the redshifted 21-cm emission induced by the gas density inhomogeneities that develop at early times in cold dark matter (CDM) dominated cosmologies; (b) the sharp absorption feature in the radio sky due to the rapid rise of the Ly_alpha continuum background that marks the birth of the first UV sources in the universe; and (c) the 21-cm emission and absorption shells that are generated on several Mpc scales around the first bright quasars. Future radio observations with projected facilities like the Giant Metrewave Radio Telescope and the Square Kilometer Array may shed light on the power spectrum of density fluctuations at z>5, and map the end of the "dark ages", i.e. the transition from the post-recombination universe to one populated with radiation sources.
225 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 10 |
| 2024 | 22 |
| 2023 | 33 |
| 2022 | 117 |
| 2021 | 17 |
| 2020 | 18 |