We measure the current expansion rate of the Universe, Hubble's constant \(H_0\), by calibrating the absolute magnitudes of supernovae to distances measured by Baryon Acoustic Oscillations. This ...`inverse distance ladder' technique provides an alternative to calibrating supernovae using nearby absolute distance measurements, replacing the calibration with a high-redshift anchor. We use the recent release of 1829 supernovae from the Dark Energy Survey spanning \(0.01\lt z \lt1.13\) anchored to the recent Baryon Acoustic Oscillation measurements from DESI spanning \(0.30 \lt z_{\mathrm{eff}} \lt 2.33\). To trace cosmology to \(z=0\), we use the third-, fourth- and fifth-order cosmographic models, which, by design, are agnostic about the energy content and expansion history of the universe. With the inclusion of the higher-redshift DESI-BAO data, the third-order model is a poor fit to both data sets, with the fourth-order model being preferred by the Akaike Information Criterion. Using the fourth-order cosmographic model, we find \(H_0=67.19^{+0.66}_{-0.64}\mathrm{~km} \mathrm{~s}^{-1} \mathrm{~Mpc}^{-1}\), in agreement with the value found by Planck without the need to assume Flat-\(\Lambda\)CDM. However the best-fitting expansion history differs from that of Planck, providing continued motivation to investigate these tensions.
We present \(griz\) photometric light curves for the full 5 years of the Dark Energy Survey Supernova program (DES-SN), obtained with both forced Point Spread Function (PSF) photometry on Difference ...Images (DIFFIMG) performed during survey operations, and Scene Modelling Photometry (SMP) on search images processed after the survey. This release contains \(31,636\) DIFFIMG and \(19,706\) high-quality SMP light curves, the latter of which contains \(1635\) photometrically-classified supernovae that pass cosmology quality cuts. This sample spans the largest redshift (\(z\)) range ever covered by a single SN survey (\(0.1<z<1.13\)) and is the largest single sample from a single instrument of SNe ever used for cosmological constraints. We describe in detail the improvements made to obtain the final DES-SN photometry and provide a comparison to what was used in the DES-SN3YR spectroscopically-confirmed SN Ia sample. We also include a comparative analysis of the performance of the SMP photometry with respect to the real-time DIFFIMG forced photometry and find that SMP photometry is more precise, more accurate, and less sensitive to the host-galaxy surface brightness anomaly. The public release of the light curves and ancillary data can be found at https://github.com/des-science/DES-SN5YR. Finally, we discuss implications for future transient surveys, such as the forthcoming Vera Rubin Observatory Legacy Survey of Space and Time (LSST).
InP-Based Type-II Quantum-Well Lasers and LEDs Sprengel, S.; Grasse, C.; Wiecha, P. ...
IEEE journal of selected topics in quantum electronics,
07/2013, Volume:
19, Issue:
4
Journal Article
Peer reviewed
Type-II InP-based light sources provide a promising concept for mid-infrared lasers. These have recently made huge progress, as the first electrically and optically pumped lasers could be ...demonstrated beyond the wavelength limit for type-I InP-based lasers (~2.3 μm). In this paper, we introduce the material system and device concepts, and report the latest achievements, such as electrically pumped lasing operation up to a wavelength of 2.6 μm in pulsed mode, continuous-wave resonant-cavity light-emitting diode operation up to a wavelength of 3.3 μm at 20-80 °C and photoluminescence even up to 3.9 μm.
We report the Australia Telescope Compact Array (ATCA) and ROSAT detection of supernova remnant (SNR) J0529−6653 in the Large Magellanic Cloud (LMC) which is positioned in the projected vicinity of ...the known radio pulsar PSR B0529−66. In the radio continuum frequencies, this LMC object follows a typical SNR structure of a shell morphology with brightened regions in the south-west. It exhibits an almost circular shape of D= 33 × 31 pc (1-pc uncertainty in each direction) and radio spectral index of α=−0.68 ± 0.03 - typical for mid-age SNRs. We also report detection of polarized regions with a peak value of ∼17 ± 7 per cent at 6 cm. An investigation of ROSAT images produced from merged Position Sensitive Proportional Counter (PSPC) data reveals the presence of extended X-ray emission coincident with the radio emission of the SNR. In X-rays, the brightest part is in the north-east. We discuss various scenarios with regard to the SNR-pulsar association with emphasis on the large age difference, lack of a pulsar trail and no prominent point-like radio or X-ray source.
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Current and future Type Ia Supernova (SN Ia) surveys will need to adopt new approaches to classifying SNe and obtaining their redshifts without spectra if they wish to reach their full potential. We ...present here a novel approach that uses only photometry to identify SNe Ia in the 5-year Dark Energy Survey (DES) dataset using the SUPERNNOVA classifier. Our approach, which does not rely on any information from the SN host-galaxy, recovers SNe Ia that might otherwise be lost due to a lack of an identifiable host. We select 2,298 high-quality SNe Ia from the DES 5-year dataset. More than 700 of these have no spectroscopic host redshift and are potentially new SNIa compared to the DES-SN5YR cosmology analysis. To analyse these SNe Ia, we derive their redshifts and properties using only their light-curves with a modified version of the SALT2 light-curve fitter. Compared to other DES SN Ia samples with spectroscopic redshifts, our new sample has in average higher redshift, bluer and broader light-curves, and fainter host-galaxies. Future surveys such as LSST will also face an additional challenge, the scarcity of spectroscopic resources for follow-up. When applying our novel method to DES data, we reduce the need for follow-up by a factor of four and three for host-galaxy and live SN respectively compared to earlier approaches. Our novel method thus leads to better optimisation of spectroscopic resources for follow-up.
The Large Magellanic Cloud (LMC) is an ideal target for the study of an unbiased and complete sample of supernova remnants (SNR). This paper presents new X-ray and radio data of the LMC SNR candidate ...DEM L205, obtained by XMM-Newton and ATCA, along with archival optical and infrared observations. The authors use data at various wavelengths to study this object and its complex neighbourhood, in particular in the context of the star formation activity around the source. Supernova remnant features are detected at all observed wavelengths, soft and extended X-ray emission is observed, arising from a thermal plasma with a temperature kT between 0.2 kiloelectron-Volts (keV) and 0.3 keV. The authors definitely confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants known in the LMC. The numerous massive stars and the recent outburst in star formation around the source strongly suggest that a core-collapse supernova is the progenitor of this remnant.
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Context. The Large Magellanic Cloud (LMC) is an ideal target for the study of an unbiased and complete sample of supernova remnants (SNRs). We started an X-ray survey of the LMC with XMM-Newton, ...which, in combination with observations at other wavelengths, will allow us to discover and study remnants that are either even fainter or more evolved (or both) than previously known. Aims. We present new X-ray and radio data of the LMC SNR candidate DEM L205, obtained by XMM-Newton and ATCA, along with archival optical and infrared observations. Methods. We use data at various wavelengths to study this object and its complex neighbourhood, in particular in the context of the star formation activity, past and present, around the source. We analyse the X-ray spectrum to derive some remnant’s properties, such as age and explosion energy. Results. Supernova remnant features are detected at all observed wavelengths : soft and extended X-ray emission is observed, arising from a thermal plasma with a temperature kT between 0.2 keV and 0.3 keV. Optical line emission is characterised by an enhanced S ii-to-Hα ratio and a shell-like morphology, correlating with the X-ray emission. The source is not or only tentatively detected at near-infrared wavelengths (shorter than 10 μm), but there is a detection of arc-like emission at mid and far-infrared wavelengths (24 and 70 μm) that can be unambiguously associated with the remnant. We suggest that thermal emission from dust heated by stellar radiation and shock waves is the main contributor to the infrared emission. Finally, an extended and faint non-thermal radio emission correlates with the remnant at other wavelengths and we find a radio spectral index between −0.7 and −0.9, within the range for SNRs. The size of the remnant is ~79 × 64 pc and we estimate a dynamical age of about 35 000 years. Conclusions. We definitely confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants known in the LMC. The numerous massive stars and the recent outburst in star formation around the source strongly suggest that a core-collapse supernova is the progenitor of this remnant.
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