The Ultra-Violet Optical Telescope on the Swift spacecraft has observed hundreds of supernovae, covering all major types and most subtypes. Here we introduce the Swift Optical/Ultraviolet Supernova ...Archive (SOUSA), which will contain all of the supernova images and photometry. We describe the observation and reduction procedures and how they impact the final data. We show photometry from well-observed examples of most supernova classes, whose absolute magnitudes and colors may be used to infer supernova types in the absence of a spectrum. A full understanding of the variety within classes and a robust photometric separation of the groups requires a larger sample, which will be provided by the final archive. The data from the existing Swift supernovae are also useful for planning future observations with Swift as well as future UV observatories.
Swift intensive accretion disk reverberation mapping of four AGN yielded light curves sampled ∼200-350 times in 0.3-10 keV X-ray and six UV/optical bands. Uniform reduction and cross-correlation ...analysis of these data sets yields three main results: (1) The X-ray/UV correlations are much weaker than those within the UV/optical, posing severe problems for the lamp-post reprocessing model in which variations in a central X-ray corona drive and power those in the surrounding accretion disk. (2) The UV/optical interband lags are generally consistent with as predicted by the centrally illuminated thin accretion disk model. While the average interband lags are somewhat larger than predicted, these results alone are not inconsistent with the thin disk model given the large systematic uncertainties involved. (3) The one exception is the U band lags, which are on average a factor of ∼2.2 larger than predicted from the surrounding band data and fits. This excess appears to be due to diffuse continuum emission from the broad-line region (BLR). The precise mixing of disk and BLR components cannot be determined from these data alone. The lags in different AGN appear to scale with mass or luminosity. We also find that there are systematic differences between the uncertainties derived by JAVELIN versus more standard lag measurement techniques, with JAVELIN reporting smaller uncertainties by a factor of 2.5 on average. In order to be conservative only standard techniques were used in the analyses reported herein.
We present the photometric calibration of the Swift Ultraviolet/Optical Telescope (UVOT) which includes: optimum photometric and background apertures, effective area curves, colour transformations, ...conversion factors for count rates to flux and the photometric zero-points (which are accurate to better than 4 per cent) for each of the seven UVOT broad-band filters. The calibration was performed with observations of standard stars and standard star fields that represent a wide range of spectral star types. The calibration results include the position-dependent uniformity, and instrument response over the 1600–8000 Å operational range. Because the UVOT is a photon-counting instrument, we also discuss the effect of coincidence loss on the calibration results. We provide practical guidelines for using the calibration in UVOT data analysis. The results presented here supersede previous calibration results.
ABSTRACT
The broad-band spectral energy distribution (SED) of active galactic nuclei (AGNs) is investigated for a well-selected sample composed of 23 Seyfert 1 galaxies observed simultaneously in the ...optical/ultraviolet (UV) and X-ray bands with the Neil Gehrels Swift Observatory. The optical to UV continuum spectra are modelled, for the first time, with emission from an accretion disc with a generalized radial temperature profile, in order to account for the intrinsic spectra which are found to be generally redder than the model prediction of the standard Shakura–Sunyaev disc (SSD, Fν ∝ ν+1/3). The power-law indices of the radial temperature profile (Teff(R) ∝ R−p, R is the radius of the accretion disc) are inferred to be p = 0.5–0.75 (a median of 0.63), deviating from the canonical p = 0.75 for the SSD model as widely adopted in previous studies. A marginal correlation of a flatter radial temperature profile (a smaller p-value) with increasing the Eddington ratio is suggested. Such a model produces generally a lower peak of accretion disc emission and thus a smaller bolometric luminosity in some of the AGN, particularly those with high Eddington ratios, than that based on the SSD model by a factor of several. The broad-band SED, the bolometric correction factors, and their dependence on some of the AGN parameters are revisited. We suggest that such non-standard SSD discs may operate in AGN and are at least partly responsible for the reddened optical/UV spectra as observed. One possible explanation for these flattened temperature profiles is the mass-loss process in form of disc winds/outflows.
The Ultraviolet/Optical Telescope (UVOT) is one of three instruments onboard the Swift observatory. The photometric calibration has been published, and this paper follows up with details on other ...aspects of the calibration including a measurement of the point spread function with an assessment of the orbital variation and the effect on photometry. A correction for large-scale variations in sensitivity over the field of view is described, as well as a model of the coincidence loss which is used to assess the coincidence correction in extended regions. We have provided a correction for the detector distortion and measured the resulting internal astrometric accuracy of the UVOT, also giving the absolute accuracy with respect to the International Celestial Reference System. We have compiled statistics on the background count rates, and discuss the sources of the background, including instrumental scattered light. In each case, we describe any impact on UVOT measurements, whether any correction is applied in the standard pipeline data processing or whether further steps are recommended.
ABSTRACT
We present the rest-frame ultraviolet (UV) galaxy luminosity function (LF) and luminosity density (LD) measurements in the far-UV (1500 Å) wavelength, in the redshift range $z$ = 0.6–1.2. ...The UV LF is derived using XMM-Newton Optical Monitor (XMM-OM), UV (1600–4000 Å) observations of the Chandra Deep Field South, over an area of 396 arcmin2. Using the deep UV imaging of the CDFS, we identified >2500 galaxies in our sample with UVW1AB ≤ 24.5 mag. This sample, along with various other catalogues containing redshift information, is used to calculate the binned representation of the galaxy UV LF in the two redshift bins 0.6 ≤ $z$ < 0.8 and 0.8 ≤ $z$ < 1.2, having a wide range of 1500 Å rest-frame UV magnitudes (ΔM1500 ≃ 3), reaching ≃ 1–1.5 magnitudes fainter than previous studies at similar redshifts. The binned LF is described well by the Schechter function form. Using maximum-likelihood, the Schechter function is fitted to the unbinned data to obtain the best-fitting values of the the UV galaxy LF parameters. We find that characteristic magnitude M* brightens by 0.8 mag from $z$ = 0.7 to $z$ = 1, implying an increase in the star formation activity between these redshifts, as reported by past studies. Our estimate of the faint-end slope $-1.10^{+0.19}_{-0.18}$ is on the shallower side compared with previous studies at $z$ = 0.7, whereas a value of $-1.56^{+0.19}_{-0.18}$ estimated for $z$ = 1.0, agrees with previous results given the uncertainties.
ABSTRACT We derive the ultraviolet (UV) luminosity function (LF) of star-forming galaxies in the redshift range z = 0.6–1.2, in the rest-frame far-UV (1500 Å) wavelength. For this work, we are in ...particular interested in the bright end of the UV LF in this redshift range. Data from the XMM–Newton Optical Monitor (XMM-OM), near-UV (2410–3565 Å) observations over 1.5 deg2 of the Cosmic evolution survey (COSMOS) field are employed for this purpose. We compile a source list of 879 sources with UVW1AB in the range ∼21–24 mag from the wide-area UVW1 image of the COSMOS field in the two bins 0.6 ≤ z ≤ 0.8 and 0.8 ≤ z ≤ 1.2. The M1500 for these sources lies in the interval − 19.10, −22.50. We use the maximum likelihood to fit a Schechter function model to the unbinned data to estimate the parameters (faint-end slope, characteristic magnitude, and normalization) of the Schechter function. We find the shape of the LF to be consistent with the Schechter model, and the parameters are in fair agreement with other studies conducted using direct measurements of the 1500 Å flux. We see a brightening of the characteristic magnitude as we move from lower (0.7) to higher (1.0) redshift. The measures for luminosity density are within the error margins of past studies. We examine the brightest sources in our sample for the active galactic nucleus contribution. These sources are characterized by their spectral energy distributions, integrated infrared (IR) luminosities, and morphologies. We also explore their overlap with the brightest IR galaxies in a similar redshift range.
As of 2019, quadrivalent influenza vaccine (QIV) has replaced trivalent influenza vaccine (TIV) in the national immunization program in The Netherlands. Target groups are individuals of 60+ years of ...age and those with chronic diseases. The objective was to estimate the incremental break-even price of QIV over TIV at a threshold of €20 000 per quality-adjusted life-year (QALY).
An age-structured compartmental dynamic model was adapted for The Netherlands to assess health outcomes and associated costs of vaccinating all individuals at higher risk for influenza with QIV instead of TIV over the seasons 2010 to 2018. Influenza incidence rates were derived from a global database. Other parameters (probabilities, QALYs and costs) were extracted from the literature and applied according to Dutch guidelines. A threshold of €20 000 per QALY was applied to estimate the incremental break-even prices of QIV versus TIV. Sensitivity analyses were performed to test the robustness of the model outcomes.
Retrospectively, vaccination with QIV instead of TIV could have prevented on average 9500 symptomatic influenza cases, 2130 outpatient visits, 84 hospitalizations, and 38 deaths per year over the seasons 2010 to 2018. This translates into 385 QALYs and 398 life-years potentially gained. On average, totals of €431 527 direct and €2 388 810 indirect costs could have been saved each year.
Using QIV over TIV during the influenza seasons 2010 to 2018 would have been cost-effective at an incremental price of maximally €3.81 (95% confidence interval, €3.26-4.31). Sensitivity analysis showed consistent findings on the incremental break-even price in the same range.
We present the calibration of the Swift Ultraviolet and Optical Telescope (UVOT ) grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands, ...respectively. The UV grism covers the range λ1700–5000 Å with a spectral resolution (λ/Δλ) of 75 at λ2600 Å for source magnitudes of u=10–16 mag, while the visible grism covers the range λ2850–6600 Å with a spectral resolution of 100 at λ4000 Å for source magnitudes of b=12–17 mag. This calibration extends over all detector positions, for all modes used during operations. The wavelength accuracy (1σ) is 9 Å in the UV grism clocked mode, 17 Å in the UV grism nominal mode and 22 Å in the visible grism. The range below λ2740 Å in the UV grism and λ5200 Å in the visible grism never suffers from overlapping by higher spectral orders. The flux calibration of the grisms includes a correction we developed for coincidence loss in the detector. The error in the coincidence loss correction is less than 20 per cent. The position of the spectrum on the detector only affects the effective area (sensitivity) by a few per cent in the nominal modes, but varies substantially in the clocked modes. The error in the effective area is from 9 per cent in the UV grism clocked mode to 15 per cent in the visible grism clocked mode.
Abstract
The XMM-Newton Serendipitous Ultraviolet Source Survey (XMM-SUSS) is a catalogue of ultraviolet (UV) sources detected serendipitously by the Optical Monitor (XMM-OM) on board the XMM-Newton ...observatory. The catalogue contains UV-detected sources collected from 2417 XMM-OM observations in one to six broad-band UV and optical filters, made between 2000 February 24 and 2007 March 29. The primary contents of the catalogue are source positions, magnitudes and fluxes in one to six passbands, and these are accompanied by profile diagnostics and variability statistics. XMM-SUSS is populated by 753 578 UV source detections above a 3σ signal-to-noise ratio threshold limit which relate to 624 049 unique objects. Taking account of substantial overlaps between observations, the net sky area covered is 29-54 deg2, depending on UV filter. The magnitude distributions peak at m
AB = 20.2, 20.9 and 21.2 in UVW2 (λeff = 2120 Å), UVM2 (λeff = 2310 Å) and UVW1 (λeff = 2910 Å), respectively. More than 10 per cent of the sources have been visited more than once using the same filter during XMM-Newton operation, and >20 per cent of sources are observed more than once per filter during an individual visit. Consequently, the scope for science based on temporal source variability on time-scales of hours to years is broad. By comparison with other astrophysical catalogues we test the accuracy of the source measurements and define the nature of the serendipitous UV XMM-OM source sample. The distributions of source colours in the UV and optical filters are shown together with the expected loci of stars and galaxies, and indicate that sources which are detected in multiple UV bands are predominantly star-forming galaxies and stars of type G or earlier.
PDF
