Showing papers by "Lise Christensen published in 2016"
TL;DR: In this article, the authors constructed a composite spectrum from luminous blue QSOs at 1 to 11'350 A without any significant host contamination, assuming a power-law continuum for the composite and finding a spectral slope of α λ = 1.70 ± 0.01.
Abstract: Quasi-stellar object (QSO) spectral templates are important both to QSO physics and for investigations that use QSOs as probes of intervening gas and dust. However, combinations of various QSO samples obtained at different times and with different instruments so as to expand a composite and to cover a wider rest frame wavelength region may create systematic effects, and the contribution from QSO hosts may contaminate the composite. We have constructed a composite spectrum from luminous blue QSOs at 1 to 11 350 A without any significant host contamination. Assuming a power-law continuum for the composite we find a spectral slope of α λ = 1.70 ± 0.01, which is steeper than previously found in the literature. We attribute the differences to our broader spectral wavelength coverage, which allows us to effectively avoid fitting any regions that are affected either by strong QSO emissions lines (e.g., Balmer lines and complex [Fe II] blends) or by intrinsic host galaxy emission. Finally, we demonstrate the application of the QSO composite spectrum for evaluating the reddening in other QSOs.
140 citations
TL;DR: In this article, the authors measured C IV lambda 1548, 1550, He II lambda 1640, OIII lambda 1661, 1666, CIII] lambda 1907, 1909, H beta, [O III] lambda lambda 4959, 5007 emission lines with FWHM less than or similar to 50 km s(-1) and fluxes spanning the interval 1.4((blue))vertical bar 8.4
Abstract: We present VLT/X-Shooter and MUSE spectroscopy of a faint F814W = 28.60 +/- 0.33 (M-UV = -17.0), low-mass (less than or similar to 10(7)M(circle dot)), and compact (R-eff = 62 pc) freshly star-forming galaxy at z = 3.1169 magnified (16x) by the Hubble Frontier Fields galaxy cluster Abell S1063. Gravitational lensing allows for a significant jump toward lowluminosity regimes, in moderately high-resolution spectroscopy (R = lambda/d lambda similar to 3000-7400). We measured C IV lambda 1548, 1550, He II lambda 1640, OIII] lambda 1661, 1666, CIII]lambda lambda 1907, 1909, H beta, [O III] lambda lambda 4959, 5007 emission lines with FWHM less than or similar to 50 km s(-1) and (de-lensed) fluxes spanning the interval 1.0 x 10(-19)-2 x 10(-18) erg s(-1) cm(-2) at signal-to-noise ratio (S/N) = 4-30. The double-peaked Ly alpha emission with Delta v(red -blue) = 280(+/- 7) km s(-1) and delensed fluxes 2.4((blue))vertical bar 8.5((red)) x 10(-18) erg s(-1) cm(-2) (S/N = 38((blue))vertical bar 110((red)) indicate a low column density of neutral hydrogen gas consistent with a highly ionized interstellar medium as also inferred from the large [O III]lambda 5007/[O II] lambda 3727 > 10 ratio. We detect C IV lambda 1548, 1550 resonant doublet in emission, each component with FWHM less than or similar to 45 km s(-1) and redshifted by + 51(+/- 10) km s(-1) relative to the systemic redshift. We interpret this as nebular emission tracing an expanding optically thin interstellar medium. Both C IV lambda 1548, 1550 and He II lambda 1640 suggest the presence of hot and massive stars (with a possible faint active galactic nucleus). The ultraviolet slope is remarkably blue, beta = -2.95 +/- 0.20 (F-lambda = lambda(beta)), consistent with a dust-free and young less than or similar to 20 Myr galaxy. Line ratios suggest an oxygen abundance 12 + log(O/H) < 7.8. We are witnessing an early episode of star formation in which a relatively low N-H I and negligible dust attenuation might favor a leakage of ionizing radiation. This galaxy currently represents a unique low-luminosity reference object for future studies of the reionization epoch with the James Webb Space Telescope.
115 citations
University of Chile1, INAF2, University of Victoria3, Space Telescope Science Institute4, University of Copenhagen5, Ohio State University6, Max Planck Society7, University of Geneva8, University of Florida9, International Centre for Theoretical Physics10, Johns Hopkins University11, International School for Advanced Studies12, University of California, Santa Cruz13, Ikerbasque14, Spanish National Research Council15, University of the Basque Country16, University of Arizona17, Leibniz Institute for Astrophysics Potsdam18
TL;DR: In this paper, the authors used the ERC-StG "cosmoIGM" grant under NSF grant (AST-1302093) to conduct a study on the physics of particle physics and cosmology.
Abstract: FONDECYT [1140838]; ERC [320596]; Danish National Research Foundation; Danish Council for Independent Research [DFF - 4002-00275]; ERC-StG "cosmoIGM"; NSF AAPF fellowship under NSF grant [AST-1302093]; European Research Council [GA-257670]; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy; Japanese Monbukagakusho; Max Planck Society; Higher Education Funding Council for England; American Museum of Natural History; Astrophysical Institute Potsdam; University of Basel; University of Cambridge; Case Western Reserve University; University of Chicago; Drexel University; Fermilab; Joint Institute for Nuclear Astrophysics; Kavli Institute for Particle Astrophysics and Cosmology; Korean Scientist Group; Chinese Academy of Sciences (LAMOST); Los Alamos National Laboratory; Max-Planck-Institute for Astronomy (MPIA); Max-Planck-Institute for Astrophysics (MPA); New Mexico State University; Ohio State University; University of Pittsburgh; University of Portsmouth; Princeton University; United States Naval Observatory; University of Washington; PRIN INAF; NSERC; National Aeronautics and Space Administration; Institute for Advanced Study; Japan Participation Group; Johns Hopkins University; [PFB-06 CATA]
87 citations
TL;DR: XQ-100 as discussed by the authors is a legacy survey of the high-redshift universe with VLT/XSHOOTER with full spectral coverage from 315 to 2500 nm at a resolving power ranging from R~4000 to 7000, depending on wavelength.
Abstract: We describe the execution and data reduction of the European Southern Observatory Large Programme "Quasars and their absorption lines: a legacy survey of the high-redshift universe with VLT/XSHOOTER" (hereafter `XQ-100'). XQ-100 has produced and made publicly available an homogeneous and high-quality sample of echelle spectra of 100 QSOs at redshifts z~3.5-4.5 observed with full spectral coverage from 315 to 2500 nm at a resolving power ranging from R~4000 to 7000, depending on wavelength. The median signal-to-noise ratios are 33, 25 and 43, as measured at rest-frame wavelengths 1700, 3000 and 3600 Angstrom, respectively. This paper provides future users of XQ-100 data with the basic statistics of the survey, along with details of target selection, data acquisition and data reduction. The paper accompanies the public release of all data products, including 100 reduced spectra. XQ-100 is the largest spectroscopic survey to date of high-redshift QSOs with simultaneous rest-frame UV/optical coverage, and as such enables a wide range of extragalactic research, from cosmology and galaxy evolution to AGN astrophysics.
77 citations
International Centre for Theoretical Physics1, University of Washington2, International School for Advanced Studies3, INAF4, University of Victoria5, University of Chile6, Space Telescope Science Institute7, University of Copenhagen8, Ohio State University9, Max Planck Society10, University of Nottingham11
TL;DR: In this article, the Lyman α flux power spectrum measurements of the XQ-100 sample of quasar spectra obtained in the context of the European Southern Observatory Large Programme ‘Quasars and their absorption lines: a legacy survey of the high redshift universe with VLT/XSHOOTER’ were presented.
Abstract: We present the Lyman α flux power spectrum measurements of the XQ-100 sample of quasar spectra obtained in the context of the European Southern Observatory Large Programme ‘Quasars and their absorption lines: a legacy survey of the high redshift universe with VLT/XSHOOTER’. Using 100 quasar spectra with medium resolution and signal-to-noise ratio, we measure the power spectrum over a range of redshifts z = 3–4.2 and over a range of scales k = 0.003–0.06 km−1 s. The results agree well with the measurements of the one-dimensional power spectrum found in the literature. The data analysis used in this paper is based on the Fourier transform and has been tested on synthetic data. Systematic and statistical uncertainties of our measurements are estimated, with a total error (statistical and systematic) comparable to the one of the BOSS data in the overlapping range of scales, and smaller by more than 50 per cent for higher redshift bins (z > 3.6) and small scales (k > 0.01 km−1 s). The XQ-100 data set has the unique feature of having signal-to-noise ratios and resolution intermediate between the two data sets that are typically used to perform cosmological studies, i.e. BOSS and high-resolution spectra (e.g. UVES/VLT or HIRES). More importantly, the measured flux power spectra span the high-redshift regime that is usually more constraining for structure formation models.
75 citations
TL;DR: In this article, the authors present a sample of 38 intervening Damped Lyman $\alpha$ (DLA) systems identified towards 100 $z>3.5$ quasars, observed during the XQ-100 survey.
Abstract: We present a sample of 38 intervening Damped Lyman $\alpha$ (DLA) systems identified towards 100 $z>3.5$ quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final combined sample consists of 742 DLAs over a redshift range approximately $1.6 < z_{\rm abs} < 5.0$. We develop a novel technique for computing $\Omega_{\rm HI}^{\rm DLA}$ as a continuous function of redshift, and we thoroughly assess and quantify the sources of error therein, including fitting errors and incomplete sampling of the high column density end of the column density distribution function. There is a statistically significant redshift evolution in $\Omega_{\rm HI}^{\rm DLA}$ ($\geq 3 \sigma$) from $z \sim 2$ to $z \sim$ 5. In order to make a complete assessment of the redshift evolution of $\Omega_{\rm HI}$, we combine our high redshift DLA sample with absorption surveys at intermediate redshift and 21cm emission line surveys of the local universe. Although $\Omega_{\rm HI}^{\rm DLA}$, and hence its redshift evolution, remains uncertain in the intermediate redshift regime ($0.1 < z_{\rm abs} < 1.6$), we find that the combination of high redshift data with 21cm surveys of the local universe all yield a statistically significant evolution in $\Omega_{\rm HI}$ from $z \sim 0$ to $z \sim 5$ ($\geq 3 \sigma$). Despite its statistical significance, the magnitude of the evolution is small: a linear regression fit between $\Omega_{\rm HI}$ and $z$ yields a typical slope of $\sim$0.17$\times 10^{-3}$, corresponding to a factor of $\sim$ 4 decrease in $\Omega_{\rm HI}$ between $z=5$ and $z=0$.
73 citations
Arizona State University1, Space Telescope Science Institute2, University of Texas at Austin3, Johns Hopkins University4, University of Copenhagen5, Pennsylvania State University6, University of Bologna7, European Southern Observatory8, University of Virginia9, Goddard Space Flight Center10, Stockholm University11
TL;DR: In this paper, the authors presented an unambiguous and first simultaneous detection of both the Lyman-Alpha emission and Lyman break from a z = 7.512 +/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS).
Abstract: Galaxies at high redshifts provide a valuable tool to study cosmic dawn, and therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of both the Lyman-Alpha emission and the Lyman break from a z = 7.512 +/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS). These spectra, taken with G102 grism on Hubble SpaceTelescope (HST), show a significant emission line detection (6 Sigma) in two observational position angles (PA), with Lyman-Alpha line flux of 1.06 +/- 0.19 x 10(exp -17) erg s(exp -1) cm(exp -2). The line flux is nearly a factor of four higher than in the archival MOSFIRE spectroscopic observations. This is consistent with other recent observations implying that ground-based near-infrared spectroscopy underestimates total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on ground-based Lyman-Alpha measurements. A 4-Alpha detection of the NV line in one PA also suggests a weak Active Galactic Nucleus (AGN), and if confirmed would make this source the highest-redshift AGN yet found.These observations from the Hubble Space Telescope thus clearly demonstrate the sensitivity of the FIGS survey, and the capability of grism spectroscopy to study the epoch of reionization.
61 citations
University of California, Berkeley1, Space Telescope Science Institute2, University of Copenhagen3, University of Illinois at Urbana–Champaign4, University of South Carolina5, University of California, Los Angeles6, California Institute of Technology7, Johns Hopkins University8, University of California, Santa Barbara9, University of California, Davis10, Rutgers University11, Las Cumbres Observatory Global Telescope Network12, New York University13, American Museum of Natural History14, University of Arizona15, University of Texas at Austin16, Stockholm University17
TL;DR: In this article, the HST light curve of supernova Refsdal has a shape consistent with the distinctive, slowly rising light curves of SN 1987A-like SNe, and they find strong evidence for a broad Hα P-Cygni profile and Na I D absorption in the hST grism spectrum at the redshift (z = 1.49) of the spiral host galaxy.
Abstract: We have acquired Hubble Space Telescope (HST) and Very Large Telescope near-infrared spectra and images of supernova (SN) Refsdal after its discovery as an Einstein cross in fall 2014. The HST light curve of SN Refsdal has a shape consistent with the distinctive, slowly rising light curves of SN 1987A-like SNe, and we find strong evidence for a broad Hα P-Cygni profile and Na I D absorption in the HST grism spectrum at the redshift (z = 1.49) of the spiral host galaxy. SNe IIn, largely powered by circumstellar interaction, could provide a good match to the light curve of SN Refsdal, but the spectrum of a SN IIn would not show broad and strong Hα and Na I D absorption. From the grism spectrum, we measure an Hα expansion velocity consistent with those of SN 1987A-like SNe at a similar phase. The luminosity, evolution, and Gaussian profile of the Hα emission of the WFC3 and X-shooter spectra, separated by ~2.5 months in the rest frame, provide additional evidence that supports the SN 1987A-like classification. In comparison with other examples of SN 1987A-like SNe, photometry of SN Refsdal favors bluer B − V and V − R colors and one of the largest luminosities for the assumed range of potential magnifications. The evolution of the light curve at late times will provide additional evidence about the potential existence of any substantial circumstellar material. Using MOSFIRE and X-shooter spectra, we estimate a subsolar host-galaxy metallicity (8.3 ± 0.1 dex and <8.4 dex, respectively) near the explosion site.
52 citations
TL;DR: In this paper, the authors presented an unambiguous and first simultaneous detection of both the Lyman-alpha emission and the Lipschitz break from a z = 7.512+/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS), using spectra taken with G102 grism on the Hubble Space Telescope (HST).
Abstract: Galaxies at high redshifts provide a valuable tool to study cosmic dawn, and therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of both the Lyman-alpha emission and the Lyman break from a z = 7.512+/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS). These spectra, taken with G102 grism on Hubble Space Telescope (HST), show a significant emission line detection (6 sigma) in multiple observational position angles (PA), with total integrated Ly{\alpha} line flux of 1.06+/- 0.12 e10-17erg s-1cm-2. The line flux is nearly a factor of four higher than the previous MOSFIRE spectroscopic observations of faint Ly{\alpha} emission at {\lambda} = 1.0347{\mu}m, yielding z = 7.5078+/- 0.0004. This is consistent with other recent observations implying that ground-based near-infrared spectroscopy underestimates total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on ground-based Lyman-{\alpha} measurements. A 4-{\sigma} detection of the NV line in one PA also suggests a weak Active Galactic Nucleus (AGN), potentially making this source the highest-redshift AGN yet found. Thus, this observation from the Hubble Space Telescope clearly demonstrates the sensitivity of the FIGS survey, and the capability of grism spectroscopy to study the epoch of reionization.
46 citations
International School for Advanced Studies1, INAF2, University of California, Santa Cruz3, University of Victoria4, University of Chile5, Space Telescope Science Institute6, University of Copenhagen7, Ohio State University8, University of California, Riverside9, University of Florida10, University of Arizona11, Max Planck Society12
TL;DR: DARK cosmology centre, PRIN INAF, NSF [AST-1109447], NSERC, DNRF, FONDECYT [1140838], NSF AAPF fellowship under NSF Grant [AST]-1302093, Danish Council for Independent Research [DFF 4002-00275], UCSC, [PFB-06 CATA]
Abstract: DARK cosmology centre; PRIN INAF; NSF [AST-1109447]; NSERC; DNRF; FONDECYT [1140838]; NSF AAPF fellowship under NSF Grant [AST-1302093]; Danish Council for Independent Research [DFF 4002-00275]; UCSC; [PFB-06 CATA]
43 citations
TL;DR: In this paper, the authors acknowledge the receipt of an NSERC Discovery Grant which supported this research, and JXP is supported by NSF grant AST-1109447 and SL has been supported by FONDECYT grant number 1140838 and partially by PFB-06 CATA.
Abstract: SLE acknowledges the receipt of an NSERC Discovery Grant which supported this research. JXP is supported by NSF grant AST-1109447. SL has been supported by FONDECYT grant number 1140838 and partially by PFB-06 CATA. KDD is supported by an NSF AAPF fellowship awarded under NSF grant AST-1302093.
INAF1, University of Cambridge2, Spanish National Research Council3, University of Bern4, University of Copenhagen5, Federal University of Rio Grande do Norte6, Leibniz Institute for Astrophysics Potsdam7, University of Göttingen8, Uppsala University9, Nicolaus Copernicus University in Toruń10, Heriot-Watt University11, Durham University12, Instituto Mauá de Tecnologia13, Heidelberg University14
TL;DR: The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics as discussed by the authors.
Abstract: The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.
INAF1, University of Cambridge2, Spanish National Research Council3, University of Bern4, University of Copenhagen5, Federal University of Rio Grande do Norte6, Leibniz Institute for Astrophysics Potsdam7, University of Göttingen8, Uppsala University9, Nicolaus Copernicus University in Toruń10, Heriot-Watt University11, Durham University12, Instituto Mauá de Tecnologia13, Heidelberg University14
TL;DR: The first generation of E-ELT instruments will include an optical-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics as discussed by the authors.
Abstract: The first generation of E-ELT instruments will include an optical-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.
TL;DR: The first detection of molecular emission from a galaxy selected to be near a projected background quasar using the Atacama Large Millimeter/submillimeter Array (ALMA) was reported in this article.
Abstract: We present the first detection of molecular emission from a galaxy selected to be near a projected background quasar using the Atacama Large Millimeter/submillimeter Array (ALMA). The ALMA detection of CO(1$-$0) emission from the $z=0.101$ galaxy toward quasar PKS 0439-433 is coincident with its stellar disk and yields a molecular gas mass of $M_{\\rm mol} \\approx 4.2 \\times 10^9 M_\\odot$ (for a Galactic CO-to-H$_2$ conversion factor), larger than the upper limit on its atomic gas mass. We resolve the CO velocity field, obtaining a rotational velocity of $134 \\pm 11$ km s$^{-1}$, and a resultant dynamical mass of $\\geq 4 \\times 10^{10} M_\\odot$. Despite its high metallicity and large molecular mass, the $z=0.101$ galaxy has a low star formation rate, implying a large gas consumption timescale, larger than that typical of late-type galaxies. Most of the molecular gas is hence likely to be in a diffuse extended phase, rather than in dense molecular clouds. By combining the results of emission and absorption studies, we find that the strongest molecular absorption component toward the quasar cannot arise from the molecular disk, but is likely to arise from diffuse gas in the galaxy's circumgalactic medium. Our results emphasize the potential of combining molecular and stellar emission line studies with optical absorption line studies to achieve a more complete picture of the gas within and surrounding high-redshift galaxies.
TL;DR: The first detection of CO(1$-$0) emission from a galaxy selected to be near a projected background quasar using the Atacama Large Millimeter/submillimeter Array (ALMA) was reported in this paper.
Abstract: We present the first detection of molecular emission from a galaxy selected to be near a projected background quasar using the Atacama Large Millimeter/submillimeter Array (ALMA). The ALMA detection of CO(1$-$0) emission from the $z=0.101$ galaxy toward quasar PKS 0439-433 is coincident with its stellar disk and yields a molecular gas mass of $M_{\rm mol} \approx 4.2 \times 10^9 M_\odot$ (for a Galactic CO-to-H$_2$ conversion factor), larger than the upper limit on its atomic gas mass. We resolve the CO velocity field, obtaining a rotational velocity of $134 \pm 11$ km s$^{-1}$, and a resultant dynamical mass of $\geq 4 \times 10^{10} M_\odot$. Despite its high metallicity and large molecular mass, the $z=0.101$ galaxy has a low star formation rate, implying a large gas consumption timescale, larger than that typical of late-type galaxies. Most of the molecular gas is hence likely to be in a diffuse extended phase, rather than in dense molecular clouds. By combining the results of emission and absorption studies, we find that the strongest molecular absorption component toward the quasar cannot arise from the molecular disk, but is likely to arise from diffuse gas in the galaxy's circumgalactic medium. Our results emphasize the potential of combining molecular and stellar emission line studies with optical absorption line studies to achieve a more complete picture of the gas within and surrounding high-redshift galaxies.
TL;DR: In this article, the authors present a strong lensing system, composed of four multiple images of a source at z = 2.387, created by two lens galaxies, G1 and G2, belonging to the galaxy cluster MACS J1115.
Abstract: We present a strong lensing system, composed of four multiple images of a source at z = 2.387, created by two lens galaxies, G1 and G2, belonging to the galaxy cluster MACS J1115.9+0129 at z = 0.353. We use observations taken as part of the Cluster Lensing and Supernova survey with Hubble, and its spectroscopic follow-up programme at the Very Large Telescope, to estimate the total mass distributions of the two galaxies and the cluster through strong gravitational lensing models. We find that the total projected mass values within the half-light radii, R-e, of the two lens galaxies are M-T,M-G1(< R-e,R- G1) = (3.6 +/- A 0.4) x 10(10) M-aS (TM) and M-T,M-G2(< R-e,R- G2) = (4.2 +/- A 1.6) x 10(10) M-aS (TM). The effective velocity dispersion values of G1 and G2 are (122 +/- A 7) km s(-1) and (137 +/- A 27) km s(-1), respectively. We remark that these values are relatively low when compared to those of a parts per thousand 200-300 km s(-1), typical of lens galaxies found in the field by previous surveys. By fitting the spectral energy distributions of G1 and G2, we measure projected luminous over total mass fractions within R-e of 0.11 +/- A 0.03, for G1, and 0.73 +/- A 0.32, for G2. The fact that the less massive galaxy, G1, is dark matter-dominated in its inner regions raises the question of whether the dark matter fraction in the core of early-type galaxies depends on their mass. Further investigating strong lensing systems will help us understand the influence that dark matter has on the structure and evolution of the inner regions of galaxies.
TL;DR: In this paper, the authors present VLT/X-Shooter and MUSE spectroscopy of an F814W =28.60+/-0.20 (F_lambda=lambda^beta), consistent with a dust-free and young ~<20 Myr galaxy.
Abstract: We present VLT/X-Shooter and MUSE spectroscopy of an faint F814W=28.60+/-0.33 (Muv=-17.0), low mass (~ 10 ratio. We detect CIV1548,1550 resonant doublet in emission, each component with FWHM ~< 45 km/s, and redshifted by +51(+/-10)km/s relative to the systemic redshift. We interpret this as nebular emission tracing an expanding optically-thin interstellar medium. Both CIV1548,1550 and HeII1640 suggest the presence of hot and massive stars (with a possible faint AGN). The ultraviolet slope is remarkably blue, beta =-2.95 +/- 0.20 (F_lambda=lambda^beta), consistent with a dust-free and young ~<20 Myr galaxy. Line ratios suggest an oxygen abundance 12+log(O/H)<7.8. We are witnessing an early episode of star-formation in which a relatively low NHI and negligible dust attenuation might favor a leakage of ionizing radiation. This galaxy currently represents a unique low-luminosity reference object for future studies of the reionization epoch with JWST.
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TL;DR: In this article, the authors present VLT/X-Shooter and MUSE spectroscopy of an intrinsically faint F814W=28.82+/-0.33 (Muv=-16.8), low mass ( 10 ratio) galaxy.
Abstract: We present VLT/X-Shooter and MUSE spectroscopy of an intrinsically faint F814W=28.82+/-0.33 (Muv=-16.8), low mass ( 10 ratio. We detect CIV1548-1550 resonant doublet in emission, each component with FWHM <~ 45 km/s, and redshifted by +51(+/-10) km/s relative to the systemic redshift. We interpret this as nebular emission tracing an expanding optically-thin interstellar medium. Both CIV1548-1550 and HeII1640 suggest the presence of hot and massive stars (with a possible faint AGN). The ultraviolet slope is remarkably blue, \beta =-2.95 (+/-0.20) (F_\lambda=\lambda^\beta), consistent with a dust-free and young <~20 Myr galaxy. We are witnessing an early episode of star-formation in which a relatively low N_HI and negligible dust attenuation might favor a leakage of ionizing radiation. This galaxy currently represents a unique low-luminosity reference object for future studies of the reionization epoch with JWST and ELT.
01 Mar 2016
TL;DR: In this paper, the authors derived a prediction for an absorber galaxy mass that depends on the DLA metallicity, and they found that metal-rich DLAs and their host galaxies follow the same redshift-dependent scaling relation between stellar mass and metheicity as luminosity-selected galaxies.
Abstract: Strong absorption lines in quasar spectra primarily probe low-mass galaxies and detecting these in emission has previously been difficult. Dedicated surveys for the host galaxies of damped Lyman-α (DLA) systems have often resulted in non-detections and upper limits. Targeting the most metal-rich absorbers has proven to be a viable method, because these galaxies are brighter. By combining DLA metallicities and deriving host galaxy stellar masses, we find that metal-rich DLAs (with >10% solar metallicity) and their host galaxies follow the same redshift-dependent scaling relation between stellar mass and metallicity as luminosity-selected galaxies. We derive a prediction for an absorber galaxy mass that depends on the DLA metallicity.