Topic
Lyman series
About: Lyman series is a research topic. Over the lifetime, 345 publications have been published within this topic receiving 10408 citations.
Papers published on a yearly basis
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Papers
TL;DR: In this article, the effects of the stochastic attenuation produced by intervening QSO absorption systems on the broadband colors of galaxies at cosmological distances were assessed, including scattering in resonant lines, such as Lyman alpha, Lyman gamma, and higher order members, and Lyman-continuum absorption.
Abstract: We assess the effects of the stochastic attenuation produced by intervening QSO absorption systems on the broadband colors of galaxies at cosmological distances. We compute the H I opacity of a clumpy universe as a function of redshift, including scattering in resonant lines, such as Lyman alpha, Lyman beta, Lyman gamma, and higher order members, and Lyman-continuum absorption. Both the numerous, optically thin Lyman-alpha forest clouds and the rarer, optically thick Lyman limit systems are found to contribute to the obscuration of background sources. We study the mean properties of primeval galaxies at high redshift in four broad optical passbands, U(sub n), B, G, and R. Even if young galaxies radiated a significant amount of ionizing photons, the attenuation due to the accumulated photoelectric opacity along the path is so severe that sources beyond z approximately 3 will drop out of the U(sub n) image together. We also show that the observed B-R color of distant galaxies can be much redder than expected from a stellar population. At z approximately 3.5, the blanketing by discrete absorption lines in the Lyman series is so effective that background galaxies appear, on average, 1 mag fainter in B. By z approximately 4, the observed B magnitude increment due to intergalactic absorption exceeds 2 mag. By modeling the intrinsic UV spectral energy distribution of star-forming galaxies with a stellar population synthesis code, we show that the (B-R)(sub AB) approximately 0 criterion for identifying 'flat-spectrum,' metal-producing galaxies is biased against objects at z greater than 3. The continuum blanketing from the Lyman series produces a characteristic staircase profile in the transmitted power. We suggest that this cosmic Lyman decrement might be used as a tool to identify high-z galaxies.
1,532 citations
TL;DR: In this article, the frequency distributions of the first six Lyman lines of hydrogen-like carbon, oxygen, neon, magnesium, aluminum, and silicon ions broadened by the local fields of both ions and electrons are calculated for dense plasmas.
Abstract: The frequency distributions of the first six Lyman lines of hydrogenlike carbon, oxygen, neon, magnesium, aluminum, and silicon ions broadened by the local fields of both ions and electrons are calculated for dense plasmas. The electron collisions are treated by an impact theory allowing (approximately) for level splittings caused by the ion fields, finite duration of the collisions, and screening of the electron fields. These calculations are fully quantum mechanical and include the full Coulomb interaction. Ion effects are calculated in the quasistatic, linear-Stark-effect approximation, using distribution functions of Hooper and Tighe which include correlation and shielding effects. Theoretical uncertainties from the various approximations are estimated, and the scaling of the profiles with density, temperature, and nuclear charge is discussed. A correction for the effects caused by low-frequency field fluctuations is suggested.
154 citations
TL;DR: In this paper, the effect of Lyman-continuum photons on the 21-cm background in the high-redshift Universe was examined, and it was shown that a proper treatment of the cascades delays the onset of strong Wouthuysen-Field coupling and affects the power spectrum of brightness fluctuations when the overall coupling is still relatively weak.
Abstract: We examine the effect of Lyman-continuum photons on the 21-cm background in the high-redshift Universe. The brightness temperature of this transition is determined by the spin temperature T s , which describes the relative populations of the singlet and triplet hyperfine states. Once the first luminous sources appear, T s is set by the Wouthuysen-Field effect, in which Lyman-series photons mix the hyperfine levels. Here we consider coupling through n > 2 Lyman photons. We first show that coupling (and heating) from scattering of Lyn photons is negligible, because they rapidly cascade to lower-energy photons. These cascades can result in either a Lya photon - which will then affect Ts according to the usual Wouthuysen-Field mechanism - or photons from the 2 s → 1 s continuum, which escape without scattering. We show that a proper treatment of the cascades delays the onset of strong Wouthuysen-Field coupling and affects the power spectrum of brightness fluctuations when the overall coupling is still relatively weak (i.e., around the time of the first stars). Cascades damp fluctuations on small scales because only ∼1/3 of Lyn photons cascade through Lya, but they do not affect the large-scale power because that arises from those photons that redshift directly into the Lyα transition. We also comment on the utility of Lyn transitions in providing 'standard rulers' with which to study the high-redshift unvierse.
149 citations
TL;DR: In this article, the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes was used to detect Lyman continuum radiation in two nearby starburst galaxies, Tol 0440-381, Tol 1247-232 and Mrk 54.
Abstract: We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232 and Mrk 54 were observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes. The three galaxies have radial velocities of ~13,000 km/s, permitting a ~35 A window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 A. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2,000 {\AA}. We developed a dedicated background subtraction method to account for temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 A. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. We determined the current star-formation properties from the far-ultraviolet continuum and spectral lines and used synthesis models to predict the Lyman continuum radiation emitted by the current population of hot stars. We discuss the various model uncertainties such as, among others, atmospheres and evolution models. Lyman continuum escape fractions were derived from a comparison between the observed and predicted Lyman continuum fluxes. Tol 1247-232, Mrk 54 and Tol 0440-381 have absolute escape fractions of (4.5 +/- 1.2)%, (2.5 +/- 0.72)% and <(7.1 +/- 1.1)%, respectively.
141 citations
TL;DR: In this article, the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes was used to detect Lyman continuum radiation in two nearby starburst galaxies, Tol 0440-381, Tol 1247-232 and Mrk 54.
Abstract: We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232 and Mrk 54 were observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes. The three galaxies have radial velocities of ~13,000 km/s, permitting a ~35 A window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 A. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2,000 {\AA}. We developed a dedicated background subtraction method to account for temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 A. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. We determined the current star-formation properties from the far-ultraviolet continuum and spectral lines and used synthesis models to predict the Lyman continuum radiation emitted by the current population of hot stars. We discuss the various model uncertainties such as, among others, atmospheres and evolution models. Lyman continuum escape fractions were derived from a comparison between the observed and predicted Lyman continuum fluxes. Tol 1247-232, Mrk 54 and Tol 0440-381 have absolute escape fractions of (4.5 +/- 1.2)%, (2.5 +/- 0.72)% and <(7.1 +/- 1.1)%, respectively.
137 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 3 |
| 2020 | 5 |
| 2019 | 6 |
| 2018 | 4 |
| 2017 | 4 |
| 2016 | 11 |