10 research outputs found
The VANDELS Survey: New constraints on the high-mass X-ray binary populations in normal star-forming galaxies at 3 < z < 5.5
Get PDFWe use VANDELS spectroscopic data overlapping with the ≃7 Ms Chandra Deep Field South survey to extend studies of high-mass X-ray binary systems (HMXBs) in 301 normal star-forming galaxies in the redshift range 3 6 may be ≳0.25 dex higher than previously estimated
The NIRVANDELS Survey: A robust detection of α-enhancement in star-forming galaxies at z ≃3.4
Get PDFWe present results from the NIRVANDELS survey on the gas-phase metallicity (Zg, tracing O/H) and stellar metallicity (Z∗, tracing Fe/H) of 33 star-forming galaxies at redshifts 2.95 3, finding (O/Fe) = 2.54 ± 0.38 × (O/Fe)⊙, with no clear dependence on M∗
The VANDELS ESO public spectroscopic survey. Observations and first data release
No full textThis paper describes the observations and the first data release (DR1) of the ESO public spectroscopic survey “VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields”. The main targets of VANDELS are star-forming galaxies at redshift 2:4 < z < 5:5, an epoch when the Universe had not yet reached 20% of its current age, and massive passive galaxies in the range 1 < z < 2:5. By adopting a strategy of ultra-long exposure times, ranging from a minimum of 20 h to a maximum of 80 h per source, VANDELS is specifically designed to be the deepest-ever spectroscopic survey of the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy covering the wavelength range 4800–10 000 Å with a sufficiently high signal-to-noise ratio to investigate the astrophysics of high-redshift galaxy evolution via detailed absorption line studies of well-defined samples of high-redshift galaxies. VANDELS-DR1 is the release of all medium-resolution spectroscopic data obtained during the first season of observations, on a 0.2 square degree area centered around the CANDELS-CDFS (Chandra deep-field south) and CANDELS-UDS (ultra-deep survey) areas. It includes data for all galaxies for which the total (or half of the total) scheduled integration time was completed. The DR1 contains 879 individual objects, approximately half in each of the two fields, that have a measured redshift, with the highest reliable redshifts reaching zspec ~ 6. In DR1 we include fully wavelengthcalibrated and flux-calibrated 1D spectra, the associated error spectrum and sky spectrum, and the associated wavelength-calibrated 2D spectra. We also provide a catalog with the essential galaxy parameters, including spectroscopic redshifts and redshift quality flags measured by the collaboration.We present the survey layout and observations, the data reduction and redshift measurement procedure, and the general properties of the VANDELS-DR1 sample. In particular, we discuss the spectroscopic redshift distribution and the accuracy of the photometric redshifts for each individual target category, and we provide some examples of data products for the various target types and the different quality flags. All VANDELS-DR1 data are publicly available and can be retrieved from the ESO archive. Two further data releases are foreseen in the next two years, and a final data release is currently scheduled for June 2020, which will include an improved rereduction of the entire spectroscopic data set
The VANDELS survey: a strong correlation between Ly alpha equivalent width and stellar metallicity at 3 <= z <= 5
No full textWe present the results of a new study investigating the relationship between observed Ly α equivalent width (Wλ(Ly α)) and the metallicity of the ionizing stellar population (Z★) for a sample of 768 star-forming galaxies at 3 ≤ z ≤ 5 drawn from the VANDELS survey. Dividing our sample into quartiles of rest-frame Wλ(Ly α) across the range −58 Å ≾ Wλ(Ly α) ≾ 110 Å, we determine Z★ from full spectral fitting of composite far-ultraviolet spectra and find a clear anticorrelation between Wλ(Ly α) and Z★. Our results indicate that Z★ decreases by a factor ≳ 3 between the lowest Wλ(Ly α) quartile (≺Wλ(Ly α)≻ = −18 Å) and the highest Wλ(Ly α) quartile (≺Wλ(Ly α)≻ = 24 Å). Similarly, galaxies typically defined as Lyman alpha emitters (LAEs; Wλ(Ly α) > 20 Å) are, on average, metal poor with respect to the non-LAE galaxy population (Wλ(Ly α) ≤ 20 Å) with Z★non-LAE ≳ 2 × Z★LAE. Finally, based on the best-fitting stellar models, we estimate that the increasing strength of the stellar ionizing spectrum towards lower Z★ is responsible for ≈15−25 per cent of the observed variation in Wλ(Ly α) across our sample, with the remaining contribution (≈75−85 per cent) being due to a decrease in the H I/dust covering fractions in low- Z★ galaxies
An investigation of interleukin-1 in graft versus host disease following allogeneic bone marrow transplantation
Get PDFAvailable from British Library Document Supply Centre- DSC:DXN055334 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
