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Rui Marques-Chaves

Publications and source records attributed to Rui Marques-Chaves.

60 records · Page 4Linked to original sources
arXiv2017

SHARDS Frontier Fields: Physical properties of a low mass Lyman-alpha emitter at z=5.75

We analyze the properties of a multiply-imaged Lyman-alpha (Lya) emitter at z=5.75 identified through SHARDS Frontier Fields intermediate-band imaging of the Hubble Frontier Fields (HFF) cluster Abell 370. The source, A370-L57, has low intrinsic luminosity (M_UV~-16.5), steep UV spectral index (β=-2.4+/-0.1), and extreme rest-frame equivalent width of Lya (EW(Lya)=420+180-120 Å). Two different gravitational lens models predict high magnification (μ~10--16) for the two detected counter-images, separated by 7", while a predicted third counter-image (μ~3--4) is undetected. We find differences of ~50% in magnification between the two lens models, quantifying our current systematic uncertainties. Integral field spectroscopy of A370-L57 with MUSE shows a narrow (FWHM=204+/-10 km/s) and asymmetric Lya profile with an integrated luminosity L(Lya)~10^42 erg/s. The morphology in the HST bands comprises a compact clump (r_e<100 pc) that dominates the Lya and continuum emission and several fainter clumps at projected distances <1 kpc that coincide with an extension of the Lya emission in the SHARDS F823W17 and MUSE observations. The latter could be part of the same galaxy or an interacting companion. We find no evidence of contribution from AGN to the Lya emission. Fitting of the spectral energy distribution with stellar population models favors a very young (t<10 Myr), low mass (M*~10^6.5 Msun), and metal poor (Z<4x10^-3) stellar population. Its modest star formation rate (SFR~1.0 Msun/yr) implies high specific SFR (sSFR~2.5x10^-7 yr^-1) and SFR density (Sigma_SFR ~ 7-35 Msun/yr/kpc^2). The properties of A370-L57 make it a good representative of the population of galaxies responsible for cosmic reionization.

astro-ph.GA↗
arXiv2017

The BOSS Emission-Line Lens Survey V. Morphology and Substructure of Lensed Lyman-$α$ Emitters at redshift $z\approx2.5$ in the BELLS GALLERY

We present a morphological study of the 17 lensed Lyman-$α$ emitter (LAE) galaxies of the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) for the GALaxy-Ly$α$ EmitteR sYstems (BELLS GALLERY) sample. This analysis combines the magnification effect of strong galaxy-galaxy lensing with the high resolution of the Hubble Space Telescope ($HST$) to achieve a physical resolution of $\sim$80 pc for this $2<z<3$ LAE sample, allowing a detailed characterization of the LAE rest-frame ultraviolet continuum surface brightness profiles and substructure. We use lens-model reconstructions of the LAEs to identify and model individual clumps, which we subsequently use to constrain the parameters of a generative statistical model of the LAE population. Since the BELLS GALLERY sample is selected primarily on the basis of Lyman-$α$ emission, the LAEs that we study here are likely to be directly comparable to those selected in wide-field narrow-band LAE surveys, in contrast with the lensed LAEs identified in cluster lensing fields. We find an LAE clumpiness fraction of approximately 88%, significantly higher than found in previous (non-lensing) studies. We find a well-resolved characteristic clump half-light radii of $\sim$350 pc, a scale comparable to the largest H II regions seen in the local universe. This statistical characterization of LAE surface-brightness profiles will be incorporated into future lensing analyses using the BELLS GALLERY sample to constrain the incidence of dark-matter substructure in the foreground lensing galaxies.

astro-ph.GA↗
arXiv2017

Discovery of a Very Bright and Intrinsically Very Luminous, Strongly Lensed Lyα Emitting Galaxy at z = 2.82 in the BOSS Emission-Line Lens Survey

We report the discovery of a very bright (r = 20.16), highly magnified, and yet intrinsically very luminous Lyα emitter (LAE) at z = 2.82. This system comprises four images in the observer plane with a maximum separation of ~ 6" and it is lensed by a z = 0.55 massive early-type galaxy. It was initially identified in the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey for GALaxy-Lyα EmitteR sYstems (BELLS GALLERY) survey, and follow-up imaging and spectroscopic observations using the Gran Telescopio Canarias (GTC) and William Herschel Telescope (WHT) confirmed the lensing nature of this system. A lens model using a singular isothermal ellipsoid in an external shear field reproduces quite well the main features of the system, yielding an Einstein radius of 2.95" +/- 0.10", and a total magnification factor for the LAE of 8.8 +/- 0.4. This LAE is one of the brightest and most luminous galaxy-galaxy strong lenses known. We present initial imaging and spectroscopy showing the basic physical and morphological properties of this lensed system.

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arXiv2016

The BOSS Emission-Line Lens Survey. IV. : Smooth Lens Models for the BELLS GALLERY Sample

We present \textsl{Hubble Space Telescope} (\textsl{HST}) F606W-band imaging observations of 21 galaxy-Ly$α$ emitter lens candidates in the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey (BELLS) for GALaxy-Ly$α$ EmitteR sYstems (BELLS GALLERY) survey. 17 systems are confirmed to be definite lenses with unambiguous evidence of multiple imaging. The lenses are primarily massive early-type galaxies (ETGs) at redshifts of approximately $0.55$, while the lensed sources are Ly$α$ emitters (LAEs) at redshifts from 2 to 3. Although the \textsl{HST} imaging data are well fit by smooth lens models consisting of singular isothermal ellipsoids in an external shear field, a thorough exploration of dark substructures in the lens galaxies is required. The Einstein radii of the BELLS GALLERY lenses are on average $60\%$ larger than those of the BELLS lenses because of the much higher source redshifts which will allow a detailed investigation of the radius evolution of the mass profile in ETGs. With the aid of the average $\sim 13 \times$ lensing magnification, the LAEs are resolved to comprise individual star-forming knots of a wide range of properties with characteristic sizes from less than 100 pc to several kpc, rest-frame far UV apparent AB magnitudes from 29.6 to 24.2, and typical projected separations of 500 pc to 2 kpc.

astro-ph.GA↗
arXiv2016

The BOSS Emission-Line Lens Survey. III. : Strong Lensing of Ly$α$ Emitters by Individual Galaxies

We introduce the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey (BELLS) for GALaxy-Ly$α$ EmitteR sYstems (BELLS GALLERY) Survey, which is a Hubble Space Telescope program to image a sample of galaxy-scale strong gravitational lens candidate systems with high-redshift Ly$α$ emitters (LAEs) as the background sources. The goal of the BELLS GALLERY Survey is to illuminate dark substructures in galaxy-scale halos by exploiting the small-scale clumpiness of rest-frame far-UV emission in lensed LAEs, and to thereby constrain the slope and normalization of the substructure-mass function. In this paper, we describe in detail the spectroscopic strong-lens selection technique, which is based on methods adopted in the previous Sloan Lens ACS (SLACS) Survey, BELLS, and SLACS for the Masses Survey. We present the BELLS GALLERY sample of the 21 highest-quality galaxy--LAE candidates selected from $\approx 1.4 \times 10^6$ galaxy spectra in the BOSS of the Sloan Digital Sky Survey III. These systems consist of massive galaxies at redshifts of approximately 0.5 strongly lensing LAEs at redshifts from 2--3. The compact nature of LAEs makes them an ideal probe of dark substructures, with a substructure-mass sensitivity that is unprecedented in other optical strong-lens samples. The magnification effect from lensing will also reveal the structure of LAEs below 100 pc scales, providing a detailed look at the sites of the most concentrated unobscured star formation in the universe. The source code used for candidate selection is available for download as a part of this release.

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