The Lyman-α‎ Line as a Probe of the Early Universe

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Simple Model ◽  
High Redshift ◽  
Young Star ◽  
H Ii Regions ◽  
Host Galaxies ◽  
Star Forming ◽  
Starting Point ◽  
Good Starting Point ◽  
High Redshift Universe

This chapter investigates a number of specific observational probes of the high-redshift Universe. It examines the Lyman-α‎ line, an extraordinarily rich and useful—albeit complex—probe of both galaxies and the intergalactic medium (IGM). As established in the previous chapter, young star-forming galaxies can produce very bright Lyman-α‎ emissions. Although the radiative transfer of these photons through their host galaxies is typically very complex, a good starting point is a simple model in which a fraction of stellar ionizing photons are absorbed within their source galaxy, forming embedded H II regions. The resulting protons and electrons then recombine, producing Lyman-α‎ photons. Assuming ionization equilibrium, the rate of these recombinations must equal the rate at which ionizing photons are produced.

The host galaxies of long gamma-ray bursts through cosmic time

2018 ◽  
Vol 27 (13) ◽  
pp. 1842001 ◽  
Author(s):  
Thomas Krühler
Keyword(s):  
Stellar Population ◽  
Gamma Ray ◽  
High Redshift ◽  
Cosmic Time ◽  
Interstellar Matter ◽  
Host Galaxies ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Dust Extinction ◽  
High Redshift Universe

As a result of their unprecedented luminosity, long [Formula: see text]-ray bursts (GRBs) and their afterglows pinpoint a population of high-redshift galaxies that is distinct and complementary to galaxies selected by deep sky surveys. In this way, GRBs facilitate a unique view into the high-redshift universe. The bright optical afterglow, for example, serves as a background light for absorption-line spectroscopy, and thus helps us to accurately characterize and understand the cosmochemical evolution of the interstellar matter, the properties of star-forming galaxies through cosmic time or dust extinction at redshifts up to [Formula: see text]. Similarly, detailed studies of the GRB explosion site, and the specific stellar population and galactic environment linked to the GRB, provide important constraints on the physical properties of the GRB progenitor like stellar mass, or on the interplay between metallicity and GRB formation. In this paper, we review recent results in both areas, focusing on novel results from extensive host observations of well-selected GRB samples.

scholarly journals Populations of OB-type stars in galaxies

2010 ◽  
Vol 6 (S272) ◽  
pp. 233-241
Author(s):  
Christopher J. Evans
Keyword(s):  
Stellar Evolution ◽  
Massive Stars ◽  
Spectral Synthesis ◽  
High Redshift ◽  
Young Star ◽  
Magellanic Clouds ◽  
Star Forming ◽  
The Galaxy ◽  
External Galaxies

AbstractOne of the challenges for stellar astrophysics is to reach the point at which we can undertake reliable spectral synthesis of unresolved populations in young, star-forming galaxies at high redshift. Here I summarise recent studies of massive stars in the Galaxy and Magellanic Clouds, which span a range of metallicities commensurate with those in high-redshift systems, thus providing an excellent laboratory in which to study the role of environment on stellar evolution. I also give an overview of observations of luminous supergiants in external galaxies out to a remarkable 6.7 Mpc, in which we can exploit our understanding of stellar evolution to study the chemistry and dynamics of the host systems.

scholarly journals Exploration of the high-redshift universe enabled by THESEUS

2021 ◽  
Author(s):  
N. R. Tanvir ◽  
E. Le Floc’h ◽  
L. Christensen ◽  
J. Caruana ◽  
R. Salvaterra ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
High Redshift ◽  
Formation Rate ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Long Duration ◽  
Absorption Studies ◽  
Population Iii Stars ◽  
High Redshift Universe

AbstractAt peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar and intergalactic medium back to the reionization era. The proposed THESEUS mission is designed to detect large samples of GRBs at z > 6 in the 2030s, at a time when supporting observations with major next generation facilities will be possible, thus enabling a range of transformative science. THESEUS will allow us to explore the faint end of the luminosity function of galaxies and the star formation rate density to high redshifts; constrain the progress of re-ionisation beyond $z\gtrsim 6$ z ≳ 6 ; study in detail early chemical enrichment from stellar explosions, including signatures of Population III stars; and potentially characterize the dark energy equation of state at the highest redshifts.

scholarly journals Multiwavelength Observations of Galactic Winds: Near and Far

2004 ◽  
Vol 217 ◽  
pp. 276-286
Author(s):  
Sylvain Veilleux
Keyword(s):  
High Redshift ◽  
Critical Discussion ◽  
Future Research ◽  
Nearby Star ◽  
Research Directions ◽  
Star Forming ◽  
Galactic Winds ◽  
Future Research Directions ◽  
Formation And Evolution ◽  
High Redshift Universe

This paper provides a critical discussion of the observational evidence for winds in our own Galaxy, in nearby star-forming and active galaxies, and in the high-redshift universe. The implications of galactic winds on the formation and evolution of galaxies and the intergalactic medium are briefly discussed. A number of observational challenges are mentioned to inspire future research directions.

scholarly journals Observations of the Lyman-α Universe

2020 ◽  
Vol 58 (1) ◽  
pp. 617-659
Author(s):  
Masami Ouchi ◽  
Yoshiaki Ono ◽  
Takatoshi Shibuya
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Formation Rate ◽  
Neutral Hydrogen ◽  
Resonant Scattering ◽  
Dark Matter Halo ◽  
Emission Data ◽  
Star Forming ◽  
High Redshift Universe

Hydrogen Lyman-α (Lyα) emission has been one of the major observational probes for the high-redshift Universe since the first discoveries of high- z Lyα-emitting galaxies in the late 1990s. Due to the strong Lyα emission originated by resonant scattering and recombination of the most abundant element, Lyα observations witness not only Hii regions of star formation and active galactic nuclei (AGNs) but also diffuse Hi gas in the circumgalactic medium (CGM) and the intergalactic medium (IGM). Here, we review Lyα sources and present theoretical interpretations reached to date. We conclude the following: ▪  A typical Lyα emitter (LAE) at z ≳ 2 with a L* Lyα luminosity is a high- z counterpart of a local dwarf galaxy, a compact metal-poor star-forming galaxy (SFG) with an approximate stellar (dark matter halo) mass and star-formation rate of 108−9M⊙ (1010−11M⊙) and 1–10 M⊙ year−1, respectively. ▪  High- z SFGs ubiquitously have a diffuse Lyα-emitting halo in the CGM extending to the halo virial radius and beyond. ▪  Remaining neutral hydrogen at the epoch of cosmic reionization makes a strong dimming of Lyα emission for galaxies at z > 6 that suggests the late reionization history. The next-generation large-telescope projects will combine Lyα emission data with Hi Lyα absorptions and 21-cm radio data that map out the majority of hydrogen (Hi+Hii) gas, uncovering the exchanges of ( a) matter by outflow and inflow and ( b) radiation, relevant to cosmic reionization, between galaxies and the CGM/IGM.

scholarly journals Observing the high redshift Universe with Euclid

2017 ◽  
Vol 12 (S333) ◽  
pp. 238-241 ◽  
Author(s):  
René Laureijs
Keyword(s):  
Spatial Distribution ◽  
Rest Frame ◽  
Near Infrared ◽  
Target Identification ◽  
High Redshift ◽  
Starting Point ◽  
The Individual ◽  
High Redshift Universe ◽  
Identification And Characterization

AbstractEuclid enables the exploration of large sky areas with diffraction limited resolution in the optical and near-infrared, and is sensitive enough to detect targets at cosmological distances. This combination of capabilities gives Euclid a clear advantage over telescope facilities with larger apertures, both on ground and in space. The decision to mount in the NISP instrument one extra grism for the wavelength range 0.92-1.3 μm with a spectral resolution of R ≈260 makes possible a rest-frame UV survey of the early Universe in the redshift range 6.5 < z < 9.7. Euclid’s standard imaging with VIS in the 0.55-0.9 μm band and with NISP in the Y, J, H bands provide complementary photometry for further target identification and characterization. Euclid is a suitable facility to discover and map the spatial distribution of rare high-redshift targets and to collect statistically relevant samples, in particular of high redshift Lyα emitters and QSOs, which can be used as signposts of the cosmic structures. The Euclid surveys are also a starting point for deeper follow up observations of the individual high-z objects. We present the Euclid mission and discuss the detectability of high-z objects to probe the epoch of ionization.

scholarly journals Modelling a bright z = 6 galaxy at the faint end of the AGN luminosity function

2020 ◽  
Vol 494 (3) ◽  
pp. 3453-3463
Author(s):  
Maxime Trebitsch ◽  
Marta Volonteri ◽  
Yohan Dubois
Keyword(s):  
Black Hole ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Stellar Populations ◽  
Star Forming ◽  
Relative Contribution ◽  
Lyman Break Galaxies ◽  
The Galaxy ◽  
Galaxy Population ◽  
High Redshift Universe

ABSTRACT Recent deep surveys have unravelled a population of faint active galactic nuclei (AGNs) in the high-redshift Universe, leading to various discussions on their nature and their role during the Epoch of Reionization. We use cosmological radiation hydrodynamics simulations of a bright galaxy at z ∼ 6 (${M_\star } \gtrsim 10^{10}\, {\rm M}_{\odot }$) hosting an actively growing supermassive black hole to study the properties of these objects. In particular, we study how the black hole and the galaxy coevolve and what is the relative contribution of the AGNs and of the stellar populations to the luminosity budget of the system. We find that the feedback from the AGN has no strong effect on the properties of the galaxy, and does not increase the total ionizing luminosity of the host. The average escape fraction of our galaxy is around $f_{\rm esc} \sim 5{{\ \rm per\ cent}}$. While our galaxy would be selected as an AGN in deep X-ray surveys, most of the ultraviolet (UV) luminosity is originating from stellar populations. This confirms that there is a transition in the galaxy population from star-forming galaxies to quasar hosts, with bright Lyman-break galaxies with MUV around −22 falling in the overlap region. Our results also suggest that faint AGNs do not contribute significantly to reionizing the Universe.

scholarly journals Massive Stars at High Redshifts

2007 ◽  
Vol 3 (S250) ◽  
pp. 415-428
Author(s):  
Max Pettini
Keyword(s):  
Massive Stars ◽  
High Redshift ◽  
Mass Function ◽  
Initial Mass Function ◽  
Stellar Spectra ◽  
Star Forming ◽  
Star Forming Regions ◽  
Look Ahead ◽  
Low Metallicity ◽  
High Redshift Universe

AbstractThe five years that have passed since the last IAU Symposium devoted to massive stars have seen a veritable explosion of data on the high redshift universe. The tools developed to study massive stars in nearby galaxies are finding increasing application to the analysis of the spectra of star-forming regions at redshifts as high as z = 7. In this brief review, I consider three topics of relevance to this symposium: the determination of the metallicities of galaxies at high redshifts from consideration of their ultraviolet stellar spectra; constraints on the initial mass function of massive stars in galaxies at z = 2 − 3; and new clues to the nucleosynthesis of carbon and nitrogen in massive stars of low metallicity. The review concludes with a look ahead at some of the questions that may occupy us for the next five years (at least!).

scholarly journals New submillimeter diagnostics of physical properties of ISM in high redshift galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 430-430
Author(s):  
Yoichi Tamura ◽  
Kouichiro Nakanishi ◽  
Kotaro Kohno ◽  
Ryohei Kawabe
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
High Redshift ◽  
Formation Rate ◽  
Host Galaxies ◽  
Power Sources ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Order Of Magnitude ◽  
New Diagnosis

AbstractWe present a new diagnosis method for determining physical properties of star-forming gas in high-z galaxies. In this method, we employed three key observational quantities, [CI], CO, and FIR luminosities, including our new detections of CO J = 4–3 emission from the pure-starburst (non-AGN) submm galaxy SMM J14011+0252 (z = 2.6) and the type-2 AGN IRAS FSC 10214+4724 (z = 2.3) obtained with the Nobeyama Millimeter Array (NMA) at the Nobeyama Radio Observatory. These two sources have extremely high star formation rate, and exhibit strong emission of CO and [CI] 609 μm lines. We determined ISM physical conditions for the two objects and another three high-z quasars in order to investigate the relationship between their ISM and power sources (i.e., massive star formation or AGN). A new PDR analysis (Wolfire et al. 2005, private communication) using CO, [CI], and FIR on five high-z sources provides new evidence that AGN host galaxies harbor denser (log nH ~ 5–6) ISM exposed to stronger far-UV fluxes of log G0 ~ 3.5–4 than the non-AGN submm galaxy. Volume filling factors of the star-forming dense gas in the AGN hosts are an order of magnitude smaller than that of the pure-starburst submm galaxy. This suggests that, in these AGN hosts, dense molecular clouds are dominating the central kpc around AGN, triggering extensive circumnuclear starbursts, and possibly feeding their central supermassive black hole simultaneously.

scholarly journals AGNs at the cosmic dawn: predictions for future surveys from a ΛCDM cosmological model

2020 ◽  
Vol 492 (2) ◽  
pp. 2535-2552
Author(s):  
Andrew J Griffin ◽  
Cedric G Lacey ◽  
Violeta Gonzalez-Perez ◽  
Claudia del P Lagos ◽  
Carlton M Baugh ◽  
...  
Keyword(s):  
Black Holes ◽  
Galaxy Formation ◽  
Near Infrared ◽  
Accretion Rate ◽  
High Redshift ◽  
Host Galaxies ◽  
Accretion Rates ◽  
Infrared Wavelengths ◽  
The Masses ◽  
High Redshift Universe

ABSTRACT Telescopes to be launched over the next decade and a half, such as JWST, EUCLID, ATHENA, and Lynx, promise to revolutionize the study of the high-redshift Universe and greatly advance our understanding of the early stages of galaxy formation. We use a model that follows the evolution of the masses and spins of supermassive black holes (SMBHs) within a semi-analytic model of galaxy formation to make predictions for the active galactic nucleus luminosity function at $z$ ≥ 7 in the broadband filters of JWST and EUCLID at near-infrared wavelengths, and ATHENA and Lynx at X-ray energies. The predictions of our model are relatively insensitive to the choice of seed black hole mass, except at the lowest luminosities (Lbol &lt; 1043 erg s−1) and the highest redshifts ($z$ &gt; 10). We predict that surveys with these different telescopes will select somewhat different samples of SMBHs, with EUCLID unveiling the most massive, highest accretion rate SMBHs, Lynx the least massive, lowest accretion rate SMBHs, and JWST and ATHENA covering objects inbetween. At $z$ = 7, we predict that typical detectable SMBHs will have masses, MBH ∼ 105–8 M⊙, and Eddington normalized mass accretion rates, $\dot{M}/\dot{M}_{\mathrm{Edd}}\sim 0.6{-}2$. The SMBHs will be hosted by galaxies of stellar mass M⋆ ∼ 108–10 M⊙, and dark matter haloes of mass Mhalo ∼ 1011–12 M⊙. We predict that the detectable SMBHs at $z$ = 10 will have slightly smaller black holes, accreting at slightly higher Eddington normalized mass accretion rates, in slightly lower mass host galaxies compared to those at $z$ = 7, and reside in haloes of mass Mhalo ∼ 1010–11 M⊙.

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