Lyman-Alpha Spectra From Multiphase Outflows, and Their Connection to Shell Models

Grönke, Max; Dijkstra, Mark

doi:10.3847/0004-637x/826/1/14

Cited by 74 publications

(43 citation statements)

References 62 publications

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“…As a consequence, the majority of the Lyα flux is peaked in the center of the galaxy and does not produce an extended Lyα spatial profile. The models from Barnes & Haehnelt (2010) also indicate that the Lyα emission becomes more centrally peaked with the increase of the velocity of the HI bulk (see also Gronke & Dijkstra 2016).…”

Section: Theoretical Modelmentioning

confidence: 87%

“…Our data do not seem to favour the presence of holes. According to Gronke & Dijkstra (2016), clumpy outflows decrease the effective optical depth seen by the Lyα photons compared to the "real" column density seen by non-resonant photons along the line of sight, and lead to a small peak shift and boosted escape fraction in comparison to a homogeneous medium of the same outflow velocity and same column density. It remains to be studied if a correlation with the spatial extension, as observed in Fig.…”

Section: Interpretation Of the Observed Small Outflow Velocitymentioning

confidence: 99%

“…However, the escape depends on a large variety of galaxy properties. It was shown by radiative transfer models, hydrodynamical simulations (Verhamme et al 2006;Laursen et al 2011;Orsi et al 2012;Duval et al 2014;Gronke & Dijkstra 2016), and observed in high-and low-redshift galaxies (Erb et al 2014;Rivera-Thorsen et al 2015;Henry et al 2015;Trainor et al 2015) that interstellar medium (ISM) dust is able to absorb Lyα photons and neutral hydrogen (HI) is able to scatter them. The emerging Lyα line profile can present two peaks (Neufeld 1990;Dijkstra et al 2006;Verhamme et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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The VIMOS Ultra Deep Survey

Guaita

Talia

Pentericci

et al. 2017

A&A

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Aims. We wish to assess the role of kinematics and neutral hydrogen column density in the escape and distribution of Lyα photons. Methods. We selected a sample of 76 Lyα emitting galaxies from the VIMOS Ultra Deep Survey (VUDS) at 2 ≤ z ≤ 4. We estimated the velocity of the neutral gas flowing out of the interstellar medium as the velocity offset, ∆v, between the systemic redshift (z sys ) and the center of low-ionization absorption line systems (LIS). To increase the signal to noise of VUDS spectra, we stacked subsamples defined based on median values of their photometric and spectroscopic properties. We measured the systemic redshift from the restframe UV spectroscopic data using the CIII]1908 nebular emission line, and we considered SiII1526 as the highest signal-to-noise LIS line. We calculated the Lyα peak shift with respect to the z sys , the EW(Lyα), and the Lyα spatial extension, Ext(Lyα-C), from the profiles in the 2D stacked spectra. Results. The galaxies that are faint in the rest-frame UV continuum, strong in Lyα and CIII], with compact UV morphology, and localized in an underdense environment are characterized by outflow velocities of the order of a few hundreds of km sec −1 . The subsamples with smaller ∆v are characterized by larger Lyα peak shifts, larger Ext(Lyα-C), and smaller EW(Lyα). In general we find that EW(Lyα) anti-correlates with Ext(LyLyα-C) and Lyα peak shift. Conclusions. We interpret these trends using a radiative-transfer shell model. The model predicts that an HI gas with a column density larger than 10 20 cm −2 is able to produce Lyα peak shifts larger than > 300 km sec −1 . An ISM with this value of N HI would favour a large amount of scattering events, especially when the medium is static, so it can explain large values of Ext(Lyα-C) and small EW(Lyα). On the contrary, an ISM with a lower N HI , but large velocity outflows would lead to a Lyα spatial profile peaked at the galaxy center (i.e. low values of Ext(Lyα-C)) and to a large EW(Lyα), as we see in our data. Our results and their interpretation via radiative-transfer models tell us that it is possible to use Lyα to study the properties of the HI gas. Also, the fact that Lyα emitters are characterized by large ∆v could give hints about their stage of evolution in the sense that they could be experiencing short bursts of star formation that push strong outflows.

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Section: Theoretical Modelmentioning

confidence: 87%

Section: Interpretation Of the Observed Small Outflow Velocitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The VIMOS Ultra Deep Survey

Guaita

Talia

Pentericci

et al. 2017

A&A

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“…2). The latter authors concluded from their observation of 91 LAEs that more than 40% of them show a double peak, and that in most cases the red component is stronger than the blue one, which is naturally explained by transfer effects in expanding media, even inhomogeneous ones (Verhamme et al , 2008(Verhamme et al , 2012Gronke & Dijkstra 2016).…”

Section: Two Other Probable Lyman Alpha Emitters At the Same Redshiftmentioning

confidence: 97%

MUSE-inspired view of the quasar Q2059-360, its Lyman α blob, and its neighborhood

North

Marino

Gorgoni

et al. 2017

A&A

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The radio-quiet quasar Q2059-360 at redshift z = 3.08 is known to be close to a small Lyman α blob (LAB) and to be absorbed by a proximate damped Lyα (PDLA) system. Here, we present the Multi Unit Spectroscopic Explorer (MUSE) integral field spectroscopy follow-up of this quasi-stellar object (QSO). Our primary goal is to characterize this LAB in detail by mapping it both spatially and spectrally using the Lyα line, and by looking for high-ionization lines to constrain the emission mechanism. Combining the high sensitivity of the MUSE integral field spectrograph mounted on the Yepun telescope at ESO-VLT with the natural coronograph provided by the PDLA, we map the LAB down to the QSO position, after robust subtraction of QSO light in the spectral domain. In addition to confirming earlier results for the small bright component of the LAB, we unveil a faint filamentary emission protruding to the south over about 80 pkpc (physical kpc); this results in a total size of about 120 pkpc. We derive the velocity field of the LAB (assuming no transfer effects) and map the Lyα line width. Upper limits are set to the flux of the N v λ1238 − 1242, C iv λ1548 − 1551, He ii λ1640, and C iii] λ1548 − 1551 lines. We have discovered two probable Lyα emitters at the same redshift as the LAB and at projected distances of 265 kpc and 207 kpc from the QSO; their Lyα luminosities might well be enhanced by the QSO radiation. We also find an emission line galaxy at z = 0.33 near the line of sight to the QSO. This LAB shares the same general characteristics as the 17 others surrounding radio-quiet QSOs presented previously. However, there are indications that it may be centered on the PDLA galaxy rather than on the QSO.

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“…Second, Gronke & Dijkstra (2016) have performed Lyα radiative transfer calculations of multiphase ISM models. The result shows that narrow Lyα profiles can be reproduced by two cases, one of which is on the condition that a galaxy has a low covering fraction of the neutral gas 4 .…”

Section: 2mentioning

confidence: 99%

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

Hashimoto

Ouchi

Shimasaku

et al. 2016

Mon. Not. R. Astron. Soc.

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We present physical properties of spectroscopically confirmed Lyα emitters (LAEs) with very large rest-frame Lyα equivalent widths EW 0 (Lyα). Although the definition of large EW 0 (Lyα) LAEs is usually difficult due to limited statistical and systematic uncertainties, we identify six LAEs selected from ∼ 3000 LAEs at z ∼ 2 with reliable measurements of EW 0 (Lyα) ≃ 200−400Å given by careful continuum determinations with our deep photometric and spectroscopic data. These large EW 0 (Lyα) LAEs do not have signatures of AGN, but notably small stellar masses of M * = 10 7−8 M ⊙ and high specific star-formation rates (star formation rate per unit galaxy stellar mass) of ∼ 100 Gyr −1 . These LAEs are characterized by the median values of L(Lyα) = 3.7 × 10 42 erg s −1 and M UV = −18.0 as well as the blue UV continuum slope of β = −2.5 ± 0.2 and the low dust extinction E(B − V ) * = 0.02 +0.04 −0.02 , which indicate a high median Lyα escape fraction of f Lyα esc = 0.68 ± 0.30. This large f Lyα esc value is explained by the low Hi column density in the ISM that is consistent with FWHM of the Lyα line, FWHM(Lyα) = 212 ± 32 km s −1 , significantly narrower than those of small EW 0 (Lyα) LAEs. Based on the stellar evolution models, our observational constraints of the large EW 0 (Lyα), the small β, and the rest-frame Heii equivalent width imply that at least a half of our large EW 0 (Lyα) LAEs would have young stellar ages of 20 Myr and very low metallicities of Z < 0.02Z ⊙ regardless of the star-formation history.

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Lyman-Alpha Spectra From Multiphase Outflows, and Their Connection to Shell Models

Cited by 74 publications

References 62 publications

The VIMOS Ultra Deep Survey

The VIMOS Ultra Deep Survey

MUSE-inspired view of the quasar Q2059-360, its Lyman α blob, and its neighborhood

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

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Lyman-Alpha Spectra From Multiphase Outflows, and Their Connection to Shell Models

Cited by 74 publications

References 62 publications

The VIMOS Ultra Deep Survey

The VIMOS Ultra Deep Survey

MUSE-inspired view of the quasar Q2059-360, its Lyman α blob, and its neighborhood

Lyα emitters with very large Lyα equivalent widths, EW0(Lyα) ≃ 200–400 Å, atz∼ 2

Contact Info

Product

Resources

About

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2