3D Lyα radiation transfer III. Constraints on gas and stellar properties of z ∼ 3 Lyman break galaxies (LBG) and implications for high-z LBGs and Lyα emitters

2008

235 citations recorded by the source corpus.

Aims. The aim of our study is to understand the variety of observed Lyα line profiles and strengths in Lyman Break Galaxies (LBGs) and Lyα emitters (LAEs), the physical parameters governing them, and hence derive constraints on the gas and dust content and stellar populations of these objects. Methods. Using our 3D Lyα radiation transfer code including gas and dust, MCLya, we fit 11 LBGs from the FORS Deep Field with redshifts between 2.8 and 5. A simple geometry of a spherically expanding shell of H i is adopted. Results. The variety of observed Lyα profiles is successfully reproduced. Most objects show outflow velocities of Vexp ∼ 150−200 km s −1 ; two objects are most likely quasi-static. The radial H i column density ranges from NHI ∼ 2 × 10 19 to 7 × 10 20 cm −2 . Our Lyα profile fits yield values of E(B − V) ∼ 0.05−0.2 for the gas extinction. We find indications for a dust-to-gas ratio higher than the Galactic value, and for a substantial scatter. The escape fraction of Lyα photons is found to be determined primarily by the extinction, and a simple fit formula is proposed. In this case a measurement of EW(Lyα)obs can yield E(B − V), if the intrinsic Lyα equivalent width is known (or assumed). Intrinsic EW(Lyα)int ∼ 50−100 A are found for 8/11 objects, as expected for stellar populations forming constantly over long periods (>10−100 Myr). In three cases we found indications of younger populations. Our model results also allow us to understand observed correlations between EW(Lyα)obs and other observables such as FWHM(Lyα), E(B − V), SFR(UV) etc. We suggest that most observed trends of Lyα, both in LBGs and LAEs, are driven by variations of NHI and the accompanying variation of the dust content. Ultimately, the main parameter responsible for these variations may be the galaxy mass. We also show that there is a clear overlap between LBGs and LAEs: at z ∼ 3 approximately 20−25% of the LBGs of Shapley et al. (2003, ApJ, 588, 65) overlap with ∼23% of the LAEs of Gronwal et al. (2007, ApJ, 667, 79). Radiation transfer and dust effects explain the increase of the LAE/LBG ratio, and a higher percentage of LBGs with strong Lyα emission with increasing redshift.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/dccc1b1be145c0978b03a6f569fa9af366e020bc

Citations in the corpus

• CANDELS: THE EVOLUTION OF GALAXY REST-FRAME ULTRAVIOLET COLORS FROM z = 8 TO 4 (2011, unknown): “We note that gas outflows in galaxies have been invoked as an escape mechanism for Ly α emission, as Ly α photons escape from outflowing gas that is redshifted with respect to the systemic redshift of the galaxy (e.g., Verhamme et al. 2008; Dijkstra & Wyithe 2010).”
• The Universe Is Reionizing at z ∼ 7: Bayesian Inference of the IGM Neutral Fraction Using Lyα Emission from Galaxies (2017, unknown): “…a highly resonant line, Lyα photons experience significant scattering within the interstellar medium (ISM) of their host galaxies, and absorption within the circumgalactic medium (CGM) which affects the visibility of emission (Verhamme et al. 2006, 2008; Dijkstra et al. 2007; Laursen et al. 2011).”
• THE STRUCTURE AND KINEMATICS OF THE CIRCUMGALACTIC MEDIUM FROM FAR-ULTRAVIOLET SPECTRA OF z ≃ 2–3 GALAXIES (2010, unknown): “There have been several recent theoretical treatments of Lyα radiative transfer in the context of galactic outflows (Verhamme et al. 2006, 2008; Schaerer & Verhamme 2008; Hansen & Oh 2006; Dijkstra et al. 2006b,a; Zheng & Miralda-Escudé 2002), and even in the highlyidealized geometric…”
• Keck spectroscopy of faint 3 < z < 7 Lyman break galaxies – I. New constraints on cosmic reionization from the luminosity and redshift-dependent fraction of Lyman α emission (2010, unknown): “…results are consistent with simple theoretical expectations in which low-luminosity galaxies are less obscured by dust (due to lower metallicities) and perhaps have lower column densities (or covering fraction) of H I surrounding them (e.g. Verhamme et al. 2006, 2008; Schaerer & Verhamme 2008).”
• PHYSICAL CONDITIONS IN A YOUNG, UNREDDENED, LOW-METALLICITY GALAXY AT HIGH REDSHIFT (2010, unknown): “From this relation and our inferred E(B − V ) = 0.02 we would predict fe = 0.7, higher than the observed value; like most of the Kornei et al. (2010) sample, BX418 falls below the Verhamme et al. (2008) prediction.”
• Cool outflows in galaxies and their implications (2020, unknown): “Remarkably, simple expanding spherical shell models (e.g., Verhamme et al. 2008; Dijkstra 2017; Gronke 2017) provide a relatively good match to the observed integrated Lyα profiles of outflowing gas in high-z galaxies, though not always (Dijkstra 2017).”
• The birth of a galaxy – III. Propelling reionization with the faintest galaxies (2014, unknown): “However, Dijkstra & Wyithe (2010) showed that a 50 kms−1 H I outflow allows for 10–20 per cent of the Lyα emission to be transmitted through a neutral IGM, still resulting in a strong EW of ∼100 Å (see also Verhamme, Schaerer & Maselli 2006; Verhamme et al. 2008).”
• THE KILOPARSEC-SCALE KINEMATICS OF HIGH-REDSHIFT STAR-FORMING GALAXIES (2009, unknown): “…into the IGM surrounding these galaxies, creating the ubiquitous blueshifted interstellar absorption features observed in rest-frame UV spectra (e.g., Pettini et al. 2002; Shapley et al. 2003), and the corresponding redshifts of the resonantly scattered Lyα emission line (Verhamme et al. 2008).”
• A STEEP FAINT-END SLOPE OF THE UV LUMINOSITY FUNCTION AT z ∼ 2–3: IMPLICATIONS FOR THE GLOBAL STELLAR MASS DENSITY AND STAR FORMATION IN LOW-MASS HALOS (2008, unknown): “10%, based on the number density of LAEs compared to the general continuum population (e.g., Kovač et al. 2007; Nagamine et al. 2008; Verhamme et al. 2008; Gawiser et al. 2007).”
• DIFFUSE Lyα EMITTING HALOS: A GENERIC PROPERTY OF HIGH-REDSHIFT STAR-FORMING GALAXIES (2011, unknown): “Gas-phase kinematics play a large role in determining how much Lyα emission escapes the galaxies, and in all of the models except those of Verhamme et al. 2008 (which do not explicitly consider the spatial distribution of Lyα emission) the dominant velocity field is associated with infall/accretion.”
• THE HETDEX PILOT SURVEY. II. THE EVOLUTION OF THE Lyα ESCAPE FRACTION FROM THE ULTRAVIOLET SLOPE AND LUMINOSITY FUNCTION OF 1.9 (2010, unknown): “To first order, the IGM transmission blueward of Lyα is ∼90%, 70%, and 50% at z ∼ 1.9, 3.0, and 3.8, respectively (Madau 1995).”
• Identification of the brightest Lyα emitters at z = 6.6 : Implications for the evolution of the luminosity function in the reionization era (2015, unknown): “…young (< 10 Myr) stars (e.g. Schaerer 2003), and Lyα is easily absorbed and re-scattered (leading to lower surface brightnesses), on average LAEs are believed to be young starbursts, while LBGs on average are slightly more evolved galaxies with a higher dust content (e.g. Verhamme et al. 2008).”
• SPECTROSCOPIC OBSERVATIONS OF LYMAN BREAK GALAXIES AT REDSHIFTS ∼4, 5, AND 6 IN THE GOODS-SOUTH FIELD (2009, unknown): “Assuming an initial interval of time (∆tLyα) in which the LBG is active as a LAE (i.e., shows conspicuous Lyα emission, with rest–frame equivalent width greater than 100Å), whose duration should be of the order of 100 − 300 Myr (e.g., Mori & Umemura 2006; Verhamme et al. 2008), the probability to o”
• ON THE REDSHIFT EVOLUTION OF THE Lyα ESCAPE FRACTION AND THE DUST CONTENT OF GALAXIES (2010, unknown): “Firstly, Verhamme et al. (2008) used radiation transport modelling of spectrally resolved Lyα features in a sample of LBGs between redshift 2.8 and 5 to estimate both dust attenuation and fLyαesc .”
• Lyα Emitting Galaxies as a Probe of Reionisation (2014, unknown): “The main properties that characterise the shell are its HI-column density, NHI, its outflow velocity, vsh, and its dust content (e.g. Ahn, Lee, & Lee 2003; Verhamme et al. 2006, 2008).”
• Lyα-EMITTING GALAXIES AT z = 2.1 IN ECDF-S: BUILDING BLOCKS OF TYPICAL PRESENT-DAY GALAXIES? (2009, unknown): “Theoretical models that include radiative transfer inside SFGs (Verhamme et al. 2006; Schaerer & Verhamme 2008; Verhamme et al. 2008; Atek et al. 2009) were also developed to understand how Lyα photons form in H ii regions and then escape the 255 256 GUAITA ET AL.”
• COMPLETING THE CENSUS OF Lyα EMITTERS AT THE REIONIZATION EPOCH (2011, unknown): “The observed large scatter in Lyα EW0 at faint UV luminosity could be due to small amounts of dust extinction (Verhamme et al. 2008) and possibly to a stochasticity of their complicated duty circle (Nagamine et al. 2010), which has not yet been clearly revealed.”
• The impact of nebular emission on the ages of z~6 galaxies (2009, unknown): “However, for shorter timescales the Hα luminosity can be larger by up to a factor∼ 4, as illustrated e.g. by (Verhamme et al. 2008, see their Fig.”
• Systematic Identification of LAEs for Visible Exploration and Reionization Research Using Subaru HSC (SILVERRUSH). I. Program strategy and clustering properties of ∼2000 Lyα emitters at z = 6–7 over the 0.3–0.5 Gpc2 survey area (2017, unknown): “The second goal is to understand the density and dynamics of H I clouds in the ISM and the CGM of starforming galaxies.”
• EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE (2011, unknown): “Clues from Lyman Alpha The properties of the Lyα profile are highly sensitive to the kinematics and distribution of the outflowing gas and dust in star-forming galaxies (e.g. Steidel et al. 2010; Hansen & Oh 2006; Verhamme et al. 2006, 2008; Kornei et al. 2010).”