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2071. 260 Ly{alpha} Emitters at Redshift z~5.7 with M2FS
ID:
ivo://CDS.VizieR/J/ApJ/903/4
Title:
260 Ly{alpha} Emitters at Redshift z~5.7 with M2FS
Short Name:
J/ApJ/903/4
Date:
15 Mar 2022
Publisher:
CDS
Description:
We present a spectroscopic survey of Ly{alpha} emitters (LAEs) at z~5.7 using the multiobject spectrograph M2FS on the Magellan Clay telescope. This is part of a high-redshift galaxy survey carried out in several well-studied deep fields. These fields have deep images in multiple UV/optical bands, including a narrow NB816 band that has allowed an efficient selection of LAE candidates at z~5.7. Our sample consists of 260 LAEs and covers a total effective area of more than 2deg^2^ on the sky. This is so far the largest (spectroscopically confirmed) sample of LAEs at this redshift. We use the secure redshifts and narrowband photometry to measure Ly{alpha} luminosities. We find that these LAEs span a Ly{alpha} luminosity range of ~2x10^42^-5x10^43^erg/s and include some of the most luminous galaxies known at z>=5.7 in terms of Ly{alpha} luminosity. Most of them have rest-frame equivalent widths between 20 and 300{AA}, and more luminous Ly{alpha} emission lines tend to have broader line widths. We detect a clear offset of ~20{AA} between the observed Ly{alpha} wavelength distribution and the NB816 filter transmission curve, which can be explained by the intergalactic medium absorption of continua blueward of Ly{alpha} in the high-redshift spectra. This sample is being used to study the Ly{alpha} luminosity function and galaxy properties at z~5.7.
2072. Ly{alpha} emitters at z~4.86
ID:
ivo://CDS.VizieR/J/ApJ/696/546
Title:
Ly{alpha} emitters at z~4.86
Short Name:
J/ApJ/696/546
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a survey for Ly{alpha} emitters at z~4.86 based on optical narrowband ({lambda}c=7126{AA}, {Delta}{lambda}=73{AA}) and broadband (B, V, r', i', and z') observations of the Cosmic Evolution Survey field using Suprime-Cam on the Subaru Telescope. We find 79 Ly{alpha} emitter (LAE) candidates at z~4.86 over a contiguous survey area of 1.83deg^2^, down to the Ly{alpha} line flux of 1.47x10^-17^erg/s/cm^2^. We obtain the Ly{alpha} luminosity function with a best-fit Schechter parameters of log L*=42.9^+0.5^_-0.3_erg/s and {Phi}*=1.2^+8.0^_-1.1_x10^-4^Mpc^-3^ for {alpha}=-1.5 (fixed). The two-point correlation function for our LAE sample is {xi}(r)=(r/4.4^+5.7^_-2.9_Mpc)^-1.90+/-0.22^. In order to investigate the field-to-field variations of the properties of Ly{alpha} emitters, we divide the survey area into nine tiles of 0.5x0.5{deg} each. We find that the number density varies with a factor of ~2 from field to field with high statistical significance. However, we find no significant field-to-field variance when we divide the field into four tiles with 0.7x0.7{deg} each. We conclude that at least 0.5deg^2^ survey area is required to derive averaged properties of LAEs at z~5, and our survey field is wide enough to overcome the cosmic variance.
2073. Ly{alpha} emitters (LAE) in A1689-7.1
ID:
ivo://CDS.VizieR/J/MNRAS/403/L54
Title:
Ly{alpha} emitters (LAE) in A1689-7.1
Short Name:
J/MNRAS/403/L54
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the discovery of a large-scale structure of emission-line galaxies at redshift z=4.86 behind a massive cluster of galaxies, A1689. Previous spectroscopic observations of a galaxy, A1689-7.1 at z=4.87, near this structure, revealed a possible overdense region of intergalactic medium (IGM) around the galaxy, which extends at least ~80 comoving Mpc along the line of sight. In order to investigate whether this z~5 IGM overdense region contains a galaxy overdensity, we undertook narrow- and broad-band imaging observations around A1689-7.1 with Subaru/Suprime-Cam. We detected 51 candidates as Ly{alpha} emitters at redshift z=4.86+/-0.03 in the 32x24-arcmin^2^ field of view. After correction for lensing by the foreground cluster, we found a large-scale (~20x60 comoving Mpc) overdense region of galaxies around A1689-7.1 in the source plane at z=4.86. The densest peak in this region has an overdensity of {delta}~4, suggesting that this structure is probably a good candidate for a protocluster which may evolve into a massive cluster of galaxies in the present-day Universe. A1689-7.1 is located at the edge of this region, where the local galaxy density is ~1.6 times the mean density and is close to the density contrast in the IGM along the line of sight to A1689-7.1 estimated from the optical depth. The overdensities of galaxies we have found may suggest that at least some parts of the IGM overdense region have already started to form galaxies and moreover they relate to the formation of a protocluster. Although we lack information on the three-dimensional distributions of both IGM and galaxy overdense regions, the similarity of the scales of both regions may suggest that the two are parts of a single large-scale structure, which would be an large edge-on sheet along the line of sight with a size of ~20x60x80 comoving Mpc.
2074. Ly{alpha} emitters near B3 J2330+3927
ID:
ivo://CDS.VizieR/J/MNRAS/400/L66
Title:
Ly{alpha} emitters near B3 J2330+3927
Short Name:
J/MNRAS/400/L66
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the discovery of a candidate of giant radio-quiet Ly{alpha} blob (RQLAB) in a large-scale structure around a high-redshift radio galaxy (HzRG) lying in a giant Ly{alpha} halo B3 J2330+3927 at redshift z=3.087. We obtained narrow- and broad-band imaging around B3 J2330+3927 with Subaru/Suprime-Cam to search for Ly{alpha} emitters (LAEs) and absorbers (LAAs) at redshift z=3.09+/-0.03. We detected candidate 127 LAEs and 26 LAAs in the field of view of 31x24arcmin^2^ (58x44 comoving Mpc).
2075. Ly{alpha} fluxes of HDFS 2.91<z<6.64 sources
ID:
ivo://CDS.VizieR/J/MNRAS/471/267
Title:
Ly{alpha} fluxes of HDFS 2.91<z<6.64 sources
Short Name:
J/MNRAS/471/267
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first estimate of the Ly{alpha} luminosity function using blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the Hubble Deep Field-South. Using automatic source-detection software, we assemble a homogeneously detected sample of 59 Ly{alpha} emitters covering a flux range of -18.0<log_10_(F)<-16.3(erg/s/cm2), corresponding to luminosities of 41.4<log_10_(L)<42.8(erg/s). As recent studies have shown, Ly{alpha} fluxes can be underestimated by a factor of 2 or more via traditional methods, and so we undertake a careful assessment of each object's Ly{alpha} flux using a curve-of-growth analysis to account for extended emission. We describe our self-consistent method for determining the completeness of the sample, and present an estimate of the global Ly {alpha} luminosity function between redshifts 2.91<z<6.64 using the 1/V_max_ estimator. We find that the luminosity function is higher than many number densities reported in the literature by a factor of 2-3, although our result is consistent at the 1{sigma} level with most of these studies. Our observed luminosity function is also in good agreement with predictions from semi-analytic models, and shows no evidence for strong evolution between the high- and low-redshift halves of the data. We demonstrate that one's approach to Ly{alpha} flux estimation does alter the observed luminosity function, and caution that accurate flux assessments will be crucial in measurements of the faint-end slope. This is a pilot study for the Ly{alpha} luminosity function in the MUSE deep-fields, to be built on with data from the Hubble Ultra Deep Field that will increase the size of our sample by almost a factor of 10.
2076. Ly{alpha} galaxies at z~4.5
ID:
ivo://CDS.VizieR/J/ApJ/671/1227
Title:
Ly{alpha} galaxies at z~4.5
Short Name:
J/ApJ/671/1227
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of 59 z~4.5 Ly{alpha}-emitting galaxies spectroscopically confirmed in a campaign of Keck DEIMOS follow-up observations to candidates selected in the Large Area Ly{alpha} (LALA) narrowband imaging survey. We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spectroscopy, we estimate a selection reliability of ~76%. Together with our previous sample of Keck LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z~4.5 Ly{alpha}-emitting galaxies in the ~0.7deg^2^ covered by the LALA imaging.
2077. Ly{alpha} profile in 43 Green Pea galaxies
ID:
ivo://CDS.VizieR/J/ApJ/844/171
Title:
Ly{alpha} profile in 43 Green Pea galaxies
Short Name:
J/ApJ/844/171
Date:
21 Oct 2021
Publisher:
CDS
Description:
We studied Lyman-{alpha} (Ly{alpha}) escape in a statistical sample of 43 Green Peas with HST/COS Ly{alpha} spectra. Green Peas are nearby star-forming galaxies with strong [OIII]{lambda}5007 emission lines. Our sample is four times larger than the previous sample and covers a much more complete range of Green Pea properties. We found that about two-thirds of Green Peas are strong Ly{alpha} line emitters with rest-frame Ly{alpha} equivalent width >20{AA}. The Ly{alpha} profiles of Green Peas are diverse. The Ly{alpha} escape fraction, defined as the ratio of observed Ly{alpha} flux to intrinsic Ly{alpha} flux, shows anti-correlations with a few Ly{alpha} kinematic features-both the blue peak and red peak velocities, the peak separations, and the FWHM of the red portion of the Ly{alpha} profile. Using properties measured from Sloan Digital Sky Survey optical spectra, we found many correlations-the Ly{alpha} escape fraction generally increases at lower dust reddening, lower metallicity, lower stellar mass, and higher [OIII]/[OII] ratio. We fit their Ly{alpha} profiles with the HI shell radiative transfer model and found that the Ly{alpha} escape fraction is anti-correlated with the best-fit N_HI_. Finally, we fit an empirical linear relation to predict f_esc_^Ly{alpha}^ from the dust extinction and Ly{alpha} red peak velocity. The standard deviation of this relation is about 0.3dex. This relation can be used to isolate the effect of intergalactic medium (IGM) scatterings from Ly{alpha} escape and to probe the IGM optical depth along the line of sight of each z>7 Ly{alpha} emission-line galaxy in the James Webb Space Telescope era.
2078. Ly{alpha} profiles of LAEs at z=3.1
ID:
ivo://CDS.VizieR/J/ApJ/751/29
Title:
Ly{alpha} profiles of LAEs at z=3.1
Short Name:
J/ApJ/751/29
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of the observations of the Ly{alpha} line profiles of 91 emission-line galaxies at z=3.1 with a spectral resolution of {lambda}/{delta}{lambda}(FWHM){approx}1700 or 180km/s. A significant fraction of ~50% of the observed objects show the characteristic double peaks in their Ly{alpha} profile. The red peak is much stronger than the blue one for most of the cases. The red peaks themselves also show weak but significant asymmetry and their widths are correlated with the velocity separation of the red and the blue peaks. This implies that the peaks are not isolated multiple components with different velocities but parts of a single line that are modified by the absorption and/or scattering by the associated neutral hydrogen gas. The characteristic profile can be naturally explained by scattering in the expanding shell of the neutral hydrogen surrounding the Ly{alpha} emitting region while the attenuation by the intergalactic medium should also be considered. Our results suggest that the star formation in these Ly{alpha} emitters are dominated by young burst-like events that produce the intrinsic Ly{alpha} emission as well as the gas outflow.
2079. Lya-UV Offsets in Galaxies at z~6
ID:
ivo://CDS.VizieR/J/MNRAS/504/3662
Title:
Lya-UV Offsets in Galaxies at z~6
Short Name:
J/MNRAS/504/3662
Date:
22 Feb 2022
Publisher:
CDS
Description:
We study the projected spatial offset between the ultraviolet continuum and Lya emission for 65 lensed and unlensed galaxies in the Epoch of Reionization 5<=z<=7, the first such study at these redshifts, in order to understand the potential for these offsets to confuse estimates of the Lya properties of galaxies observed in slit spectroscopy. While we find that ~40% of galaxies in our sample show significant projected spatial offsets, |Delta_Lya-UV_|, we find a relatively modest average (median) projected offset of |Delta_Lya-UV_|=0.61+/-0.08 proper kpc for the entire sample. A small fraction of our sample, ~10%, exhibit offsets in excess of 2 proper kpc, with offsets seen up to ~4 proper kpc, sizes that are considerably larger than the effective radii of typical galaxies at these redshifts. An internal comparison and a comparison to studies at lower redshift yielded no significant evidence of evolution of Delta_Lya-UV with redshift. In our sample, UV-bright galaxies (with a median L_UV_/L*_UV_=0.67) showed offsets a factor of three greater than their fainter counterparts (median L_UV_/L*_UV_=0.10), 0.89 +/-0.18 vs. 0.27+/-0.05 proper kpc, respectively. The presence of companion galaxies and early-stage merging activity appeared to be unlikely causes of these offsets. Rather, these offsets appear consistent with a scenario in which internal anisotropic processes resulting from stellar feedback, which is stronger in UV-brighter galaxies, facilitate Lya fluorescence and/or backscattering from nearby or outflowing gas. The reduction in the Lya flux due to offsets was quantified. It was found that the differential loss of Lya photons for galaxies with average offsets is not, if corrected for, a limiting factor for all but the narrowest slit widths (<0.4"). However, for the largest offsets, if they are mostly perpendicular to the slit major axis, slit losses were found to be extremely severe in cases where slit widths of <=1" were employed, such as those planned for James Webb Space Telescope/NIRSpec observations.
2080. Lyman {alpha} blob LAB 1 MUSE data
ID:
ivo://CDS.VizieR/J/A+A/642/A55
Title:
Lyman {alpha} blob LAB 1 MUSE data
Short Name:
J/A+A/642/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Lyman {alpha} blobs (LABs) are large-scale radio-quiet Lyman {alpha} (Ly{alpha}) nebula at high-z that occur predominantly in overdense proto-cluster regions. In particular, there is the prototypical SSA22a-LAB1 at z=3.1 which has become an observational reference. We want to understand the powering mechanisms that drive the LAB so that we may gain empirical insights into the galaxy-formation processes within a rare dense environment at high-z. Thus, we need to infer the distribution, the dynamics, and the ionisation state of LAB 1's Ly{alpha} emitting gas. LAB 1 was observed for 17.2h with the VLT/MUSE integral-field spectrograph. We produced optimally extracted narrow band images, in Ly{alpha} {lambda}1216, HeII {lambda}1640, and we tried to detect CIV {lambda}1549 emission. By utilising a moment-based analysis, we mapped the kinematics and the line profile characteristics of the blob. We also linked the inferences from the line profile analysis to previous results from imaging polarimetry. We map Ly{alpha} emission from the blob down to surface-brightness limits of ~6x10^-19^erg/s/cm^2^/arcsec^2^. At this depth, we reveal a bridge between LAB 1 and its northern neighbour LAB 8, as well as a shell-like filament towards the south of LAB 1. The complexity and morphology of the Ly{alpha} profile vary strongly throughout the blob. Despite the complexity, we find a coherent large-scale east-west velocity gradient of ~1000km/s that is aligned perpendicular to the major axis of the blob. Moreover, we observe a negative correlation of Ly{alpha} polarisation fraction with Ly{alpha} line width and a positive correlation with absolute line-of-sight velocity. Finally, we reveal HeII emission in three distinct regions within the blob, however, we can only provide upper limits for CIV. Various gas excitation mechanisms are at play in LAB 1: ionising radiation and feedback effects dominate near the embedded galaxies, while Ly{alpha} scattering contributes at larger distances. However, HeII/Ly{alpha} ratios combined with upper limits on CIV/Ly{alpha} are not able to discriminate between active galactic nucleus (AGN) ionisation and feedback-driven shocks. The alignment of the angular momentum vector parallel to the morphological principal axis appears to be at odds with the predicted norm for high-mass halos, but this most likely reflects that LAB 1 resides at a node of multiple intersecting filaments of the cosmic web. LAB 1 can thus be thought of as a progenitor of a present-day massive elliptical within a galaxy cluster.