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Träfflista för sökning "WFRF:(Caruana J.) "

Sökning: WFRF:(Caruana J.)

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2.
  • Amati, L., et al. (författare)
  • The THESEUS space mission concept : science case, design and expected performances
  • 2018
  • Ingår i: Advances in Space Research. - : ELSEVIER SCI LTD. - 0273-1177 .- 1879-1948. ; 62:1, s. 191-244
  • Tidskriftsartikel (refereegranskat)abstract
    • THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1 sr) with 0.5-1 arcmin localization, an energy band extending from several MeV down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift similar to 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late '20s/early '30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).
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3.
  • Hashimoto, T., et al. (författare)
  • The MUSE Hubble Ultra Deep Field Survey X. Ly alpha equivalent widths at 2.9 < z < 6.6
  • 2017
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 608
  • Tidskriftsartikel (refereegranskat)abstract
    • We present rest-frame Ly alpha equivalent widths (EW0) of 417 Ly alpha emitters (LAEs) detected with Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) at 2.9 < z < 6.6 in the Hubble Ultra Deep Field. Based on the deep MUSE spectroscopy and ancillary Hubble Space Telescope (HST) photometry data, we carefully measured EW0 values taking into account extended Ly alpha emission and UV continuum slopes (beta). Our LAEs reach unprecedented depths, both in Ly alpha luminosities and UV absolute magnitudes, from log (L-Ly alpha/erg s(-1)) similar to 41.0 to 43.0 and from M-UV similar to -16 to -21 (0.01-1.0 L-z=3(*)). The EW0 values span the range of similar to 5 to 240 angstrom or larger, and their distribution can be well fitted by an exponential law N = N-0 exp(-EW0/w(0)). Owing to the high dynamic range in M-UV, we find that the scale factor, w(0), depends on M-UV in the sense that including fainter M-UV objects increases w(0), i.e., the Ando effect. The results indicate that selection functions affect the EW0 scale factor. Taking these effects into account, we find that our w(0) values are consistent with those in the literature within 1 sigma uncertainties at 2.9 < z < 6.6 at a given threshold of M-UV and LLy alpha. Interestingly, we find 12 objects with EW0> 200 angstrom above 1 sigma uncertainties. Two of these 12 LAEs show signatures of merger or AGN activity: the weak Civ lambda 1549 emission line. For the remaining 10 very large EW0 LAEs, we find that the EW0 values can be reproduced by young stellar ages (< 100 Myr) and low metallicities (less than or similar to 0.02 Z(circle dot)). Otherwise, at least part of the Ly alpha emission in these LAEs needs to arise from anisotropic radiative transfer effects, fluorescence by hidden AGN or quasi-stellar object activity, or gravitational cooling.
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4.
  • Sluman, Maayke A., et al. (författare)
  • Education as important predictor for successful employment in adults with congenital heart disease worldwide
  • 2019
  • Ingår i: Congenital Heart Disease. - 1747-079X .- 1747-0803. ; 14:3, s. 362-371
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundConflicting results have been reported regarding employment status and work ability in adults with congenital heart disease (CHD). Since this is an important determinant for quality of life, we assessed this in a large international adult CHD cohort.MethodsData from 4028 adults with CHD (53% women) from 15 different countries were collected by a uniform survey in the cross-sectional APPROACH International Study. Predictors for employment and work limitations were studied using general linear mixed models.ResultsMedian age was 32 years (IQR 25-42) and 94% of patients had at least a high school degree. Overall employment rate was 69%, but varied substantially among countries. Higher education (OR 1.99-3.69) and having a partner (OR 1.72) were associated with more employment; female sex (OR 0.66, worse NYHA functional class (OR 0.67-0.13), and a history of congestive heart failure (OR 0.74) were associated with less employment. Limitations at work were reported in 34% and were associated with female sex (OR 1.36), increasing age (OR 1.03 per year), more severe CHD (OR 1.31-2.10), and a history of congestive heart failure (OR 1.57) or mental disorders (OR 2.26). Only a university degree was associated with fewer limitations at work (OR 0.62).ConclusionsThere are genuine differences in the impact of CHD on employment status in different countries. Although the majority of adult CHD patients are employed, limitations at work are common. Education appears to be the main predictor for successful employment and should therefore be encouraged in patients with CHD.
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5.
  • Verhamme, A., et al. (författare)
  • Recovering the systemic redshift of galaxies from their Lyman alpha line profile
  • 2018
  • Ingår i: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 478:1, s. L60-L65
  • Tidskriftsartikel (refereegranskat)abstract
    • The Lyman alpha (Ly alpha) line of Hydrogen is a prominent feature in the spectra of star-forming galaxies, usually redshifted by a few hundreds of km s(-1) compared to the systemic redshift. This large offset hampers follow-up surveys, galaxy pair statistics, and correlations with quasar absorption lines when only Ly alpha is available. We propose diagnostics that can be used to recover the systemic redshift directly from the properties of the Ly alpha line profile. We use spectroscopic observations of Ly alpha emitters for which a precise measurement of the systemic redshift is available. Our sample contains 13 sources detected between z approximate to 3 and z approximate to 6 as part of various multi-unit spectroscopic explorer guaranteed time observations. We also include a compilation of spectroscopic Ly alpha data from the literature spanning a wide redshift range (z approximate to 0-8). First, restricting our analysis to double-peaked Ly alpha spectra, we find a tight correlation between the velocity offset of the red peak with respect to the systemic redshift, V-peak(red), and the separation of the peaks. Secondly, we find a correlation between V-peak(red) and the full width at half-maximum of the Ly alpha line. Fitting formulas to estimate systemic redshifts of galaxies with an accuracy of <= 100 km s(-1), when only the Ly alpha emission line is available, are given for the two methods.
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6.
  • Drake, A. B., et al. (författare)
  • The MUSE Hubble Ultra Deep Field Survey VI. The faint-end of the Lyα luminosity function at 2.91
  • 2017
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 608
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the deepest study to date of the Ly alpha luminosity function in a blank field using blind integral field spectroscopy from MUSE. We constructed a sample of 604 Ly alpha emitters (LAEs) across the redshift range 2.91 < z < 6.64 using automatic detection software in the Hubble Ultra Deep Lield. The deep data cubes allowed us to calculate accurate total Ly alpha fluxes capturing low surface-brightness extended Ly alpha emission now known to be a generic property of high-redshift star-forming galaxies. We simulated realistic extended LAEs to fully characterise the selection function of our samples, and performed flux-recovery experiments to test and correct for bias in our determination of total Ly alpha fluxes. We find that an accurate completeness correction accounting for extended emission reveals a very steep faint-end slope of the luminosity function, alpha, down to luminosities of log(10) L erg s(-1) < 41.5, applying both the 1/V-max and maximum likelihood estimators. Splitting the sample into three broad redshift bins, we see the faint-end slope increasing from -2.03(-0.07)(+1.42) at z approximate to 3.44 to -2.86(-infinity)(+0.76) Z approximate to 76 at z approximate to 5.48, however no strong evolution is seen between the 68% confidence regions in L*-alpha parameter space. Using the Ly alpha line flux as a proxy for star formation activity, and integrating the observed luminosity functions, we find that LAEs' contribution to the cosmic star formation rate density rises with redshift until it is comparable to that from continuum-selected samples by z approximate to 6. This implies that LAEs may contribute more to the star-formation activity of the early Universe than previously thought, as any additional intergalactic medium (IGM) correction would act to further boost the Ly alpha luminosities. Linally, assuming fiducial values for the escape of Ly alpha and LyC radiation, and the dumpiness of the IGM, we integrated the maximum likelihood luminosity function at 5.00 < z < 6.64 and find we require only a small extrapolation beyond the data (<1 dex in luminosity) for LAEs alone to maintain an ionised IGM at z approximate to 6.
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7.
  • Ko, Jong Mi, et al. (författare)
  • Physical Activity-Related Drivers of Perceived Health Status in Adults With Congenital Heart Disease
  • 2018
  • Ingår i: American Journal of Cardiology. - : Elsevier. - 0002-9149 .- 1879-1913. ; 122:8, s. 1437-1442
  • Tidskriftsartikel (refereegranskat)abstract
    • Data on the differential impact of physical activity on perceived health status (PHS) in a large adult congenital heart disease (ACHD) patient population are lacking. We conducted a cross-sectional assessment of 4,028 ACHD patients recruited from 24 ACHD-specialized centers in 15 countries across 5 continents to examine the association between physical activity and PHS in a large international cohort of ACHD patients. A linear analog scale of the EuroQol-5D 3 level version and the 12-item Short Form Health Survey-version 2 were used to assess self-reported health status and the Health-Behavior Scale-Congenital Heart Disease was used as a subjective measurement of physical activity type, participation, and level. Correlation analyses and Wilcoxon Rank Sum tests examined bivariate relations between sample characteristics and PHS scores. Then, multivariable models were constructed to understand the impact of physical activity on PHS. Only 30% of our sample achieved recommended physical activity levels. Physically active patients reported better PHS than sedentary patients; however, the amount of physical activity was not associated with PHS. Further statistical analyses demonstrated that specifically sport participation regardless of physical activity level was a predictor of PHS. In conclusion, the majority of ACHD patients across the world are physically inactive. Sport participation appears to be the primary physical activity-related driver of PHS. By promoting sport-related exercise ACHD specialists thus may improve PHS in ACHD patients.
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8.
  • Urrutia, T., et al. (författare)
  • The MUSE-Wide Survey : survey description and first data release
  • 2019
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 624
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the MUSE-Wide survey, a blind, 3D spectroscopic survey in the CANDELS/GOODS-S and CANDELS/COSMOS regions. The final survey will cover 100 x 1 arcmin(2) MUSE fields. Each MUSE-Wide pointing has a depth of one hour and hence targets more extreme and more luminous objects over ten times the area of the MUSE-Deep fields. The legacy value of MUSE-Wide lies in providing spectroscopy of everything without photometric pre-selection. We describe the data reduction, post-processing and PSF characterization of the first 44 CANDELS /GOODS-S MUSE-Wide pointings released with this publication. Using a 3D matched filtering approach we detect 1602 emission line sources, including 479 Lyman-alpha (Ly alpha) emitting galaxies with redshifts 2.9 less than or similar to z less than or similar to 6.3. We cross-matched the emission line sources to existing photometric catalogs, finding almost complete agreement in redshifts (photometric and spectroscopic) and stellar masses for our low redshift (z < 1.5) emitters. At high redshift, we only find similar to 55% matches to photometric catalogs. We encounter a higher outlier rate and a systematic offset of Delta z similar or equal to 0.2 when comparing our MUSE redshifts with photometric redshifts from the literature. Cross-matching the emission line sources with X-ray catalogs from the Chandra Deep Field South, we find 127 matches, mostly in agreement with the literature redshifts, including ten objects with no prior spectroscopic identification. Stacking X-ray images centered on our Ly alpha emitters yields no signal; the Ly alpha population is not dominated by even low luminosity AGN. Other cross-matches of our emission-line catalog to radio and submillimeter data, yielded far lower numbers of matches, most of which already were covered by the X-ray catalog. A total of 9205 photometrically selected objects from the CANDELS survey lie in the MUSE-Wide footprint, of which we provide optimally extracted 1D spectra. We are able to determine the spectroscopic redshift of 98% of 772 photometrically selected galaxies brighter than 24th F775W magnitude. All the data in the first data release - datacubes, catalogs, extracted spectra, maps - are available on the MUSE-Wide data release webpage.
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10.
  • Spiers, H, et al. (författare)
  • Self propagating high temperature synthesis of magnesium zinc ferrites (MgxZn1-xFe2O3): thermal imaging and time resolved X-ray diffraction experiments
  • 2004
  • Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry. - 1364-5501. ; 14:7, s. 1104-1111
  • Tidskriftsartikel (refereegranskat)abstract
    • Spinel ferrites of the form MgxZn1-xFe2O4 ( x = 0. 0.25, 0.50, 0.75, 1.00) were prepared by self-propagating high-temperature synthesis (SHS) from reactions of iron(III), zinc and magnesium oxides, iron powder and sodium perchlorate. The driving force for the reactions is the oxidation of iron powder. Reactions were carried out in the presence of an external magnetic field of 0.2 or 1.1 T. Reaction velocity and temperatures were obtained by thermal imaging camera. The transformation of reactants to products was studied by time resolved X-ray diffraction using Rietveld refinement for determination of phase percentages. Reactions typically reached temperatures in excess of 1150 degreesC with a timescale of complete conversion of reactant to products of 20 s. All materials were characterised by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDXA), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Mossbauer spectroscopy and vibrating sample magnetometry (VSM).
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