Highlights • Discrepancies exist between EMR and self-report. • This may increase as vaccines become available in more non-traditional settings. • Discrepancies exist by vaccine, particularly ...positive predictive value. • Minorities had higher disconcordance compared to whites. • Some discrepancies were found by education, income and employment.
The detailed nature of type Ia supernovae (SNe Ia) remains uncertain, and as survey statistics increase, the question of astrophysical systematic uncertainties arises, notably that of the evolution ...of SN Ia populations. We study the dependence on redshift of the SN Ia
SALT2.4
light-curve stretch, which is a purely intrinsic SN property, to probe its potential redshift drift. The SN stretch has been shown to be strongly correlated with the SN environment, notably with stellar age tracers. We modeled the underlying stretch distribution as a function of redshift, using the evolution of the fraction of young and old SNe Ia as predicted using the SNfactory dataset, and assuming a constant underlying stretch distribution for each age population consisting of Gaussian mixtures. We tested our prediction against published samples that were cut to have marginal magnitude selection effects, so that any observed change is indeed astrophysical and not observational in origin. In this first study, there are indications that the underlying SN Ia stretch distribution evolves as a function of redshift, and that the age drifting model is a better description of the data than any time-constant model, including the sample-based asymmetric distributions that are often used to correct Malmquist bias at a significance higher than 5
σ
. The favored underlying stretch model is a bimodal one, composed of a high-stretch mode shared by both young and old environments, and a low-stretch mode that is exclusive to old environments. The precise effect of the redshift evolution of the intrinsic properties of a SN Ia population on cosmology remains to be studied. The astrophysical drift of the SN stretch distribution does affect current Malmquist bias corrections, however, and thereby the distances that are derived based on SN that are affected by observational selection effects. We highlight that this bias will increase with surveys covering increasingly larger redshift ranges, which is particularly important for the Large Synoptic Survey Telescope.
Context. Both multi-messenger astronomy and new high-throughput wide-field surveys require flexible tools for the selection and analysis of astrophysical transients. Aims. Here we introduce the alert ...management, photometry, and evaluation of light curves (AMPEL) system, an analysis framework designed for high-throughput surveys and suited for streamed data. AMPEL combines the functionality of an alert broker with a generic framework capable of hosting user-contributed code; it encourages provenance and keeps track of the varying information states that a transient displays. The latter concept includes information gathered over time and data policies such as access or calibration levels. Methods. We describe a novel ongoing real-time multi-messenger analysis using AMPEL to combine IceCube neutrino data with the alert streams of the Zwicky Transient Facility (ZTF). We also reprocess the first four months of ZTF public alerts, and compare the yields of more than 200 different transient selection functions to quantify efficiencies for selecting Type Ia supernovae that were reported to the Transient Name Server (TNS). Results. We highlight three channels suitable for (1) the collection of a complete sample of extragalactic transients, (2) immediate follow-up of nearby transients, and (3) follow-up campaigns targeting young, extragalactic transients. We confirm ZTF completeness in that all TNS supernovae positioned on active CCD regions were detected. Conclusions. AMPEL can assist in filtering transients in real time, running alert reaction simulations, the reprocessing of full datasets as well as in the final scientific analysis of transient data. This is made possible by a novel way of capturing transient information through sequences of evolving states, and interfaces that allow new code to be natively applied to a full stream of alerts. This text also introduces a method by which users can design their own channels for inclusion in the AMPEL live instance that parses the ZTF stream and the real-time submission of high-quality extragalactic supernova candidates to the TNS.
Early-time observations of Type Ia supernovae (SNe Ia) are essential to constrain the properties of their progenitors. In this paper, we present high-quality light curves of 127 SNe Ia discovered by ...the Zwicky Transient Facility (ZTF) in 2018. We describe our method to perform forced point-spread function photometry, which can be applied to other types of extragalactic transients. With a planned cadence of six observations per night (three g + three r), all of the 127 SNe Ia are detected in both g and r bands more than 10 days (in the rest frame) prior to the epoch of g-band maximum light. The redshifts of these objects range from z = 0.0181 to 0.165; the median redshift is 0.074. Among the 127 SNe, 50 are detected at least 14 days prior to maximum light (in the rest frame), with a subset of nine objects being detected more than 17 days before g-band peak. This is the largest sample of young SNe Ia collected to date; it can be used to study the shape and color evolution of the rising light curves in unprecedented detail. We discuss six peculiar events in this sample: one 02cx-like event ZTF18abclfee (SN 2018crl), one Ia-CSM SN ZTF18aaykjei (SN 2018cxk), and four objects with possible super-Chandrasekhar mass progenitors: ZTF18abhpgje (SN 2018eul), ZTF18abdpvnd (SN 2018dvf), ZTF18aawpcel (SN 2018cir), and ZTF18abddmrf (SN 2018dsx).
Current time domain facilities are discovering hundreds of new galactic and extra-galactic transients every week. Classifying the ever-increasing number of transients is challenging, yet crucial to ...furthering our understanding of their nature, discovering new classes, and ensuring sample purity, for instance, for Supernova Ia cosmology. The Zwicky Transient Facility is one example of such a survey. In addition, it has a dedicated very-low resolution spectrograph, the SEDMachine, operating on the Palomar 60-inch telescope. This spectrograph’s primary aim is object classification. In practice most, if not all, transients of interest brighter than ∼19 mag are typed. This corresponds to approximately 10–15 targets a night. In this paper, we present a fully automated pipeline for the SEDMachine. This pipeline has been designed to be fast, robust, stable and extremely flexible. pysedm enables the fully automated spectral extraction of a targeted point source object in less than five minutes after the end of the exposure. The spectral color calibration is accurate at the few percent level. In the 19 weeks since pysedm entered production in early August of 2018, we have classified, among other objects, about 400 Type Ia supernovae and 140 Type II supernovae. We conclude that low resolution, fully automated spectrographs such as the “SEDMachine with pysedm” installed on 2-m class telescopes within the southern hemisphere could allow us to automatically and simultaneously type and obtain a redshift for most (if not all) bright transients detected by LSST within z < 0.2, notably potentially all Type Ia Supernovae. In comparison with the current SEDM design, this would require higher spectral resolution (R ≳ 1000) and slightly improved throughput. With this perspective in mind, pysedm is designed to easily be adaptable to any IFU-like spectrograph.
We present spectroscopic observations of the host galaxies of 82 low-redshift Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory. We determine star formation rates, ...gas-phase/stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age/mass/metallicity are found: fainter, faster declining events tend to be hosted by older/massive/metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher mass/metallicity galaxies also appear brighter after stretch/colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy-targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low-mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with an SN delay-time distribution proportional to t
−1. Finally, we found no significant difference in the mass–metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.
Background
The use of prophylactic abdominal drainage following pancreaticoduodenectomy (PD) is controversial as its therapeutic value is uncertain. However, the diagnosis of postoperative pancreatic ...fistula (POPF), the main cause of PD‐associated morbidity, is often based on drain pancreatic amylase (DPA) levels. The aim of this study was to assess the predictive value of DPA, plasma pancreatic amylase (PPA) and serum C‐reactive protein (CRP) for diagnosing POPF after PD.
Methods
Patients undergoing PD with prophylactic drainage between 2008 and 2012 were studied prospectively. DPA, PPA and CRP levels were obtained daily. Differences between groups with clinically relevant POPF (International Study Group on Pancreatic Fistula (ISGPF) grade B/C) and without clinically relevant POPF (no POPF or ISGPF grade A) were evaluated. Receiver operating characteristic (ROC) analyses were performed to determine the value of DPA, PPA and CRP in prediction of POPF. Risk profiles for clinically relevant POPF were constructed and related to the intraoperative pancreatic risk assessment.
Results
Fifty‐nine (18·7 per cent) of 315 patients developed clinically relevant POPF. DPA, PPA and CRP levels on postoperative day (POD) 1–3 differed significantly between the study groups. In predicting POPF, the DPA level on POD 1 (cut‐off at 1322 units/l; odds ratio (OR) 24·61, 95 per cent confidence interval 11·55 to 52·42) and POD 2 (cut‐off at 314 units/l; OR 35·45, 14·07 to 89·33) was superior to that of PPA on POD 1 (cut‐off at 177 units/l; OR 13·67, 6·46 to 28·94) and POD 2 (cut‐off at 98 units/l; OR 16·97, 8·33 to 34·59). When DPA was combined with CRP (cut‐off on POD 3 at 202 mg/l; OR 16·98, 8·43 to 34·21), 90·3 per cent of postoperative courses could be predicted correctly (OR 44·14, 16·89 to 115·38).
Conclusion
The combination of serum CRP and DPA adequately predicted the development of clinically relevant pancreatic fistula following PD.
Serum C‐reactive protein and drain amylase are useful
Context. A new class of super-luminous transients has recently been identified. These objects reach absolute luminosities of Mu < −21, lack hydrogen in their spectra, and are exclusively ...discovered by non-targeted surveys because they are associated with very faint galaxies. Aims. We aim to contribute to a better understanding of these objects by studying SN 2006oz, a newly-recognized member of this class. Methods. We present multi-color light curves of SN 2006oz from the SDSS-II SN Survey that cover its rise time, as well as an optical spectrum that shows that the explosion occurred at z ~ 0.376. We fitted black-body functions to estimate the temperature and radius evolution of the photosphere and used the parametrized code SYNOW to model the spectrum. We constructed a bolometric light curve and compared it with explosion models. In addition, we conducted a deep search for the host galaxy with the 10 m GTC telescope. Results. The very early light curves show a dip in the g- and r-bands and a possible initial cooling phase in the u-band before rising to maximum light. The bolometric light curve shows a precursor plateau with a duration of 6–10 days in the rest-frame. A lower limit of Mu < − 21.5 can be placed on the absolute peak luminosity of the SN, while the rise time is constrained to be at least 29 days. During our observations, the emitting sphere doubled its radius to ~2 × 1015 cm, while the temperature remained hot at ~15 000 K. As for other similar SNe, the spectrum is best modeled with elements including O ii and Mg ii, while we tentatively suggest that Fe iii might be present. The host galaxy is detected in gri with 25.74 ± 0.19, 24.43 ± 0.06, and 24.14 ± 0.12, respectively. It is a faint dwarf galaxy with Mg = −16.9. Conclusions. We suggest that the precursor plateau might be related to a recombination wave in a circumstellar medium (CSM) and discuss whether this is a common property of all similar explosions. The subsequent rise can be equally well described by input from a magnetar or by ejecta-CSM interaction, but the models are not well constrained owing to the lack of post-maximum observations, and CSM interaction has difficulties accounting for the precursor plateau self-consistently. Radioactive decay is less likely to be the mechanism that powers the luminosity. The host is a moderately young and star-forming, but not a starburst, galaxy.
Abstract
We show how spectra of Type Ia supernovae (SNe Ia) at maximum light can be used to improve cosmological distance estimates. In a companion article, we used manifold learning to build a ...three-dimensional parameterization of the intrinsic diversity of SNe Ia at maximum light that we call the “Twins Embedding.” In this article, we discuss how the Twins Embedding can be used to improve the standardization of SNe Ia. With a single spectrophotometrically calibrated spectrum near maximum light, we can standardize our sample of SNe Ia with an rms of 0.101 ± 0.007 mag, which corresponds to 0.084 ± 0.009 mag if peculiar velocity contributions are removed and to 0.073 ± 0.008 mag if a larger reference sample were obtained. Our techniques can standardize the full range of SNe Ia, including those typically labeled as peculiar and often rejected from other analyses. We find that traditional light-curve width + color standardization such as SALT2 is not sufficient. The Twins Embedding identifies a subset of SNe Ia, including, but not limited to, 91T-like SNe Ia whose SALT2 distance estimates are biased by 0.229 ± 0.045 mag. Standardization using the Twins Embedding also significantly decreases host-galaxy correlations. We recover a host mass step of 0.040 ± 0.020 mag compared to 0.092 ± 0.026 mag for SALT2 standardization on the same sample of SNe Ia. These biases in traditional standardization methods could significantly impact future cosmology analyses if not properly taken into account.
As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization of Type Ia supernovae (SN Ia) for cosmology, we have statistically classified a large ...sample of nearby SNe Ia into those that are located in predominantly younger or older environments. This classification is based on the specific star formation rate measured within a projected distance of 1 kpc from each SN location (LsSFR). This is an important refinement compared to using the local star formation rate directly, as it provides a normalization for relative numbers of available SN progenitors and is more robust against extinction by dust. We find that the SNe Ia in predominantly younger environments are Δ
Y
= 0.163 ± 0.029 mag (5.7
σ
) fainter than those in predominantly older environments after conventional light-curve standardization. This is the strongest standardized SN Ia brightness systematic connected to the host-galaxy environment measured to date. The well-established step in standardized brightnesses between SNe Ia in hosts with lower or higher total stellar masses is smaller, at Δ
M
= 0.119 ± 0.032 mag (4.5
σ
), for the same set of SNe Ia. When fit simultaneously, the environment-age offset remains very significant, with Δ
Y
= 0.129 ± 0.032 mag (4.0
σ
), while the global stellar mass step is reduced to Δ
M
= 0.064 ± 0.029 mag (2.2
σ
). Thus, approximately 70% of the variance from the stellar mass step is due to an underlying dependence on environment-based progenitor age. Also, we verify that using the local star formation rate alone is not as powerful as LsSFR at sorting SNe Ia into brighter and fainter subsets. Standardization that only uses the SNe Ia in younger environments reduces the total dispersion from 0.142 ± 0.008 mag to 0.120 ± 0.010 mag. We show that as environment-ages evolve with redshift, a strong bias, especially on the measurement of the derivative of the dark energy equation of state, can develop. Fortunately, data that measure and correct for this effect using our local specific star formation rate indicator, are likely to be available for many next-generation SN Ia cosmology experiments.
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