2012ApJ...745...33K


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.16CEST20:57:59

2012ApJ...745...33K - Astrophys. J., 745, 33 (2012/January-3)

The kinematics of multiple-peaked Lyα emission in star-forming galaxies at z ∼ 2-3.

KULAS K.R., SHAPLEY A.E., KOLLMEIER J.A., ZHENG Z., STEIDEL C.C. and HAINLINE K.N.

Abstract (from CDS):

We present new results on the Lyα emission-line kinematics of 18 z ∼ 2-3 star-forming galaxies with multiple-peaked Lyα profiles. With our large spectroscopic database of UV-selected star-forming galaxies at these redshifts, we have determined that ∼30% of such objects with detectable Lyα emission display multiple-peaked emission profiles. These profiles provide additional constraints on the escape of Lyα photons due to the rich velocity structure in the emergent line. Despite recent advances in modeling the escape of Lyα from star-forming galaxies at high redshifts, comparisons between models and data are often missing crucial observational information. Using Keck II NIRSPEC spectra of Hα (z ∼ 2) and [O III]λ5007 (z ∼ 3), we have measured accurate systemic redshifts, rest-frame optical nebular velocity dispersions, and emission-line fluxes for the objects in the sample. In addition, rest-frame UV luminosities and colors provide estimates of star formation rates and the degree of dust extinction. In concert with the profile sub-structure, these measurements provide critical constraints on the geometry and kinematics of interstellar gas in high-redshift galaxies. Accurate systemic redshifts allow us to translate the multiple-peaked Lyα profiles into velocity space, revealing that the majority (11/18) display double-peaked emission straddling the velocity-field zero point with stronger red-side emission. Interstellar absorption-line kinematics suggest the presence of large-scale outflows for the majority of objects in our sample, with an average measured interstellar absorption velocity offset of > = -230 km/s. A comparison of the interstellar absorption kinematics for objects with multiple- and single-peaked Lyα profiles indicate that the multiple-peaked objects are characterized by significantly narrower absorption line widths. We compare our data with the predictions of simple models for outflowing and infalling gas distributions around high-redshift galaxies. While popular "shell" models provide a qualitative match with many of the observations of Lyα emission, we find that in detail there are important discrepancies between the models and data, as well as problems with applying the framework of an expanding thin shell of gas to explain high-redshift galaxy spectra. Our data highlight these inconsistencies, as well as illuminating critical elements for success in future models of outflow and infall in high-redshift galaxies.

Abstract Copyright:

Journal keyword(s): galaxies: formation - galaxies: high-redshift - galaxies: ISM - line: profiles - radiative transfer

Nomenclature: Table 1: [ESS2003] QHHMM-AANNN, N=12 added.

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 [ESS2003] Q0100-MD40 EmG 01 03 18.9710 +13 17 02.841           ~ 1 0
2 [ESS2003] Q0100-BX288 EmG 01 03 20.9310 +13 16 23.569           ~ 1 0
3 [ESS2003] Q0449-BX167 EmG 04 52 24.6240 -16 39 15.284           ~ 1 0
4 NAME Cosmic Horseshoe G 11 48 33.10 +19 30 03.2           ~ 67 0
5 SAS-LBG Westphal-D29 G 14 17 25.92 +52 29 32.1           ~ 4 0
6 [ESS2003] Q1549-BX102 EmG 15 51 55.9770 +19 12 44.220           ~ 1 0
7 [MSN2013] C20 EmG 15 52 00.3960 +19 08 40.773     25.09     ~ 2 0
8 [MSN2013] M22 EmG 15 52 02.7030 +19 09 40.011     24.77 24.85   ~ 3 0
9 [ESS2003] Q1549-BX202 EmG 15 52 05.0900 +19 12 49.818           ~ 1 0
10 [ESS2003] Q1623-BX129 EmG 16 25 28.7320 +26 49 19.182           ~ 1 0
11 [ESS2003] Q2206-BX151 EmG 22 08 48.6500 -19 42 25.569           ~ 1 0
12 SAS-LBG SSA22a-D17 G 22 17 18.87 +00 18 16.8       24.29   ~ 11 0
13 SAS-LBG SSA22a-C49 G 22 17 19.80 +00 18 19.0       23.81   ~ 13 0
14 [SGP96] SSA 22 C20 G 22 17 22.88 +00 16 09.5           ~ 6 0
15 SAS-LBG SSA22a-C32 G 22 17 25.61 +00 16 13.0       23.64   ~ 7 0
16 [ESS2003] Q2343-BX70 EmG 23 45 55.9340 +12 44 50.317           ~ 1 0
17 [ESS2003] Q2343-BX231 EmG 23 46 20.1080 +12 46 16.812           ~ 1 0
18 [ESS2003] Q2346-BX181 EmG 23 48 31.8270 +00 21 39.077           ~ 1 0

    Equat.    Gal    SGal    Ecl

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