Early-time spectroscopic modelling of the transitional Type Ia Supernova 2021rhu with TARDIS

An open question in SN Ia research is where the boundary lies between 'normal' Type Ia supernovae (SNe Ia) that are used in cosmological measurements and those that sit off the Phillips relation. We present the spectroscopic modelling of one such '86G-like' transitional SN Ia, SN 2021rhu, that has recently been employed as a local Hubble Constant calibrator using a tip of the red-giant branch measurement. We detail its modelling from -12 d until maximum brightness using the radiative-transfer spectral-synthesis code tardis. We base our modelling on literature delayed-detonation and deflagration models of Chandrasekhar mass white dwarfs, as well as the double-detonation models of sub-Chandrasekhar mass white dwarfs. We present a new method for 'projecting' abundance profiles to different density profiles for ease of computation. Due to the small velocity extent and low outer densities of the W7 profile, we find it inadequate to reproduce the evolution of SN 2021rhu as it fails to match the high-velocity calcium components. The host extinction of SN 2021rhu is uncertain but we use modelling with and without an extinction correction to set lower and upper limits on the abundances of individual species. Comparing these limits to literature models we conclude that the spectral evolution of SN 2021rhu is also incompatible with double-detonation scenarios, lying more in line with those resulting from the delayed detonation mechanism (although there are some discrepancies, in particular a larger titanium abundance in SN 2021rhu compared to the literature). This suggests that SN 2021rhu is likely a lower luminosity, and hence lower temperature, version of a normal SN Ia.Comment: 25 pages, 22 figures, accepted for publication in MNRA

Protection of apple and pear flowers against fire blight infections using biocontrol organisms applied via bumble bees

During bloom apple and pear are susceptible to fire blight infection which occurs when Erwinia amylovora bacteria colonize the stigma and subsequently reach, due to rain or dew droplets, the flower hypanthium where they penetrate the openings of the nectary or nectarthodes. First the flowers necrotize then the peduncles, the shoots and finally the complete stem. While the disease gradually spreads through the tissues, ooze droplets are formed that contain high concentrations of bacteria. In Belgium the infection risk increases with increasing temperature making the secondary bloom later in the season more vulnerable than the primary bloom in early spring when night temperatures are still low and frost occurs. Similarly, trees that are planted late in the season and flower in summer as well as young fruits and shoots damaged by hail in the summer can become rapidly infected by E. amylovora. This infection is worsened if ooze droplets are present in the orchard. The current strategies for control focus on preventive treatments such as sprayings with plant defense enhancer molecules like fosethyl aluminium (Aliette®) and laminarin (Vacciplant®) as well as with heavy metals including copper and manganese that help to reduce the inoculum in the orchard during the season. To avoid phytotoxicity the Aliette® treatments are done before and/or after bloom making the use of biocontrol organisms (BCOs) during bloom an attractive approach to protect the flowers. Although the antagonistic yeast Aureobasidium pullulans (Blossom ProtectTM) that can block flower colonization by E. amylovora is registered in Belgium, its use is limited today. As flowers gradually open, the BCO should be sprayed at least two to three times during bloom to protect all flowers, which is time consuming and expensive. In the research project that is presented here, we aim at a continuous application of the BCO at the sites of flower infection (i.e. stigma and hypanthium) by bumble bee (Bombus terrestris) vectoring. Besides A. pullulans, also existing BCO strains of Bacillus subtilis and Pantoea agglomerans as well as a new strain of Paenibacillus polymyxa are tested. A search for new candidate BCOs naturally present in apple and pear flower microbiomes is also ongoing. Initial results show that (i) under optimal infection conditions there is a risk of E. amylovora spread by bumble bees after visiting infected flowers (ii) BCOs are acquired to a variable degree by bumble bees, (iii) in 2015 primary bloom flower visitation in the orchard was absent in pear and limited in apple, whereas bumble bees visited secondary flowers of both better and (iv) tested BCOs show potential for fire blight control in the greenhouse.status: publishe

Disentangling the association between kidney function and atrial fibrillation: a bidirectional Mendelian randomization study

Background: The potential bidirectional causal association between kidney function and atrial fibrillation (AF) remains unclear. Methods: We conducted a bidirectional two-sample Mendelian randomization (MR) analysis. From multiple genome-wide association studies (GWAS), we retrieved genetic variants associated with kidney function (estimated glomerular filtration rate based on creatinine (eGFRcreat), blood urea nitrogen (BUN), chronic kidney disease (CKD stage ≥G3): n = 1,045,620, eGFR based on cystatin C: n = 24,063-32,861, urine albumin-tocreatinine ratio (UACR), and microalbuminuria: n = 564,257), and AF (n = 1,030,836). The inverse-variance weighted method was used as our main analysis. Results: MR analyses supported a causal effect of CKD (n = 9 SNPs, odds ratio (OR): 1.10, 95% confidence interval (CI): 1.04–1.17, p-value = 1.97 × 10− 03), and microalbuminuria (n = 5 SNPs, OR: 1.26, 95% CI: 1.10–1.46, pvalue = 1.38 × 10− 03) on AF risk. We also observed a causal effect of AF on eGFRcreat (n = 97 SNPs, OR: 1.00, 95% CI: 1.00–1.00, p-value = 6.78 × 10− 03), CKD (n = 107 SNPs, OR: 1.06, 95% CI: 1.03–1.09, p-value = 2.97 × 10− 04), microalbuminuria (n = 83 SNPs, OR: 1.07, 95% CI: 1.04–1.09, p-value = 2.49 × 10− 08), and a suggestive causal effect on eGFRcys (n = 103 SNPs, OR: 0.99, 95% CI: 0.99–1.00, p-value = 4.61 × 10− 02). Sensitivity analyses, including weighted median estimator, MR-Egger, the MR pleiotropy residual sum and outlier test, and excluding genetic variants associated with possible confounders and/or horizontal mediators (myocardial infarction/coronary artery disease, heart failure) indicated that these findings were robust. Conclusions: Our results supported a bidirectional causal association between kidney function and AF. The shared genetic architecture between kidney dysfunction and AF might represent potential important therapeutic targets to prevent both conditions in the general population

Left ventricular remodelling and prognosis after discharge in new-onset acute heart failure with reduced ejection fraction

Aims: This study aimed to investigate the left ventricular (LV) remodelling and long-term prognosis of patients with new-onset acute heart failure (HF) with reduced ejection fraction who were pharmacologically managed and survived until hospital discharge. We compared patients with ischaemic and non-ischaemic aetiology. Methods and results: This cohort study consisted of 111 patients admitted with new-onset acute HF in the period 2008–2016 [62% non-ischaemic aetiology, 48% supported by inotropes, vasopressors, or short-term mechanical circulatory devices, and left ventricular ejection fraction (LVEF) at discharge 28% (interquartile range 22–34)]. LV dimensions, LVEF, and mitral valve regurgitation were used as markers for LV remodelling during up to 3 years of follow-up. Both patients with non-ischaemic and ischaemic HF had significant improvement in LVEF (P < 0.001 and P = 0.004, respectively) with significant higher improvement in those with non-ischaemic HF (17% vs. 6%, P < 0.001). Patients with non-ischaemic HF had reduction in LV end-diastolic and end-systolic diameters (6 and 10 mm, both P < 0.001), but this was not found in those with ischaemic HF [+3 mm (P = 0.09) and +2 mm (P = 0.07), respectively]. During a median follow-up of 4.6 years, 98 patients (88%) did not reach the composite endpoint of LV assist device implantation, heart transplantation, or all-cause mortality, with no difference between with ischaemic and non-ischaemic HF [hazard ratio 0.69 (95% confidence interval 0.19–2.45)]. Conclusions: Patients with new-onset acute HF with reduced ejection fraction discharged on optimal medical treatment have a good prognosis. We observed a considerable LV remodelling with improvement in LV function and dimensions, starting already at 6 months in patients with non-ischaemic HF but not in their ischaemic counterparts

Left ventricular remodelling and prognosis after discharge in new-onset acute heart failure with reduced ejection fraction

Aims: This study aimed to investigate the left ventricular (LV) remodelling and long-term prognosis of patients with new-onset acute heart failure (HF) with reduced ejection fraction who were pharmacologically managed and survived until hospital discharge. We compared patients with ischaemic and non-ischaemic aetiology. Methods and results: This cohort study consisted of 111 patients admitted with new-onset acute HF in the period 2008–2016 [62% non-ischaemic aetiology, 48% supported by inotropes, vasopressors, or short-term mechanical circulatory devices, and left ventricular ejection fraction (LVEF) at discharge 28% (interquartile range 22–34)]. LV dimensions, LVEF, and mitral valve regurgitation were used as markers for LV remodelling during up to 3 years of follow-up. Both patients with non-ischaemic and ischaemic HF had significant improvement in LVEF (P &lt; 0.001 and P = 0.004, respectively) with significant higher improvement in those with non-ischaemic HF (17% vs. 6%, P &lt; 0.001). Patients with non-ischaemic HF had reduction in LV end-diastolic and end-systolic diameters (6 and 10 mm, both P &lt; 0.001), but this was not found in those with ischaemic HF [+3 mm (P = 0.09) and +2 mm (P = 0.07), respectively]. During a median follow-up of 4.6 years, 98 patients (88%) did not reach the composite endpoint of LV assist device implantation, heart transplantation, or all-cause mortality, with no difference between with ischaemic and non-ischaemic HF [hazard ratio 0.69 (95% confidence interval 0.19–2.45)]. Conclusions: Patients with new-onset acute HF with reduced ejection fraction discharged on optimal medical treatment have a good prognosis. We observed a considerable LV remodelling with improvement in LV function and dimensions, starting already at 6 months in patients with non-ischaemic HF but not in their ischaemic counterparts.</p

Searching for late-time interaction signatures in Type Ia supernovae from the Zwicky Transient Facility

International audienceThe nature of the progenitor systems and explosion mechanisms that give rise to Type Ia supernovae (SNe Ia) are still debated. The interaction signature of circumstellar material (CSM) being swept up by expanding ejecta can constrain the type of system from which it was ejected. Most previous studies have focused on finding CSM ejected shortly before the SN Ia explosion still residing close to the explosion site, resulting in short delay times until the interaction starts. We use a sample of 3627 SNe Ia from the Zwicky Transient Facility discovered between 2018 and 2020 and search for interaction signatures over 100 days after peak brightness. By binning the late-time light curve data to push the detection limit as deep as possible, we identify potential late-time rebrightening in 3 SNe Ia (SN 2018grt, SN 2019dlf, SN 2020tfc). The late-time detections occur between 550 and 1450 d after peak brightness, have mean absolute $r$-band magnitudes of -16.4 to -16.8 mag and last up to a few hundred days, significantly brighter than the late-time CSM interaction discovered in the prototype SN 2015cp. The late-time detections all occur within 0.8 kpc of the host nucleus and are not easily explained by nuclear activity, another transient at a similar sky position, or data quality issues. This suggests environment or specific progenitor characteristics playing a role in producing potential CSM signatures in these SNe Ia. By simulating the ZTF survey we estimate that <0.5 per cent of normal SNe Ia display late-time strong H $\alpha$-dominated CSM interaction. This is equivalent to an absolute rate of $8_{-4}^{+20}$ to $54_{-26}^{+91}$ Gpc$^{-3}$ yr$^{-1}$ assuming a constant SN Ia rate of $2.4\times10^{-5}$ Mpc$^{-3}$ yr$^{-1}$ for $z \leq 0.1$. Weaker interaction signatures, more similar to the strength seen in SN 2015cp, could be more common but are difficult to constrain with our survey depth

SN 2016ije: An SN 2002es-like Type Ia Supernova Exploded in a Metal-poor and Low-surface Brightness Galaxy

We have conducted photometric and spectroscopic observations of the peculiar Type Ia supernova (SN Ia) 2016ije that was discovered through the Tsinghua-NAOC Transient Survey. This peculiar object exploded in the outskirts of a metal-poor, low-surface brightness galaxy (i.e., M _g = −14.5 mag). Our photometric analysis reveals that SN 2016ije is subluminous ( ${M}_{B,\max }$ = −17.65 ± 0.06 mag) but exhibits relatively broad light curves (Δ m _15 ( B ) = 1.35 ± 0.14 mag), similar to the behavior of SN 2002es. Our analysis of the bolometric light curve indicates that only 0.14 ± 0.04 M _⊙ of ^56 Ni was synthesized in the explosion of SN 2016ije, which suggests a less energetic thermonuclear explosion when compared to normal SNe Ia, and this left a considerable amount of unburned materials in the ejecta. Spectroscopically, SN 2016ije resembles other SN 2002es-like SNe Ia, except that the ejecta velocity inferred from its carbon absorption line (∼4500 km s ^−1 ) is much lower than that from silicon lines (∼8300 km s ^−1 ) at around the maximum light. Additionally, most of the absorption lines are broader than other 02es-like SNe Ia. These peculiarities suggest the presence of significant unburned carbon in the inner region and a wide line-forming region along the line of sight. These characteristics suggest that SN 2016ije might originate from the violent merger of a white dwarf binary system, when viewed near an orientation along the iron-group-element cavity caused by the companion star

SN 2016ije: An SN 2002es-like Type Ia Supernova Exploded in a Metal-poor and Low-surface Brightness Galaxy

We have conducted photometric and spectroscopic observations of the peculiar Type Ia supernova (SN Ia) 2016ije that was discovered through the Tsinghua-NAOC Transient Survey. This peculiar object exploded in the outskirts of a metal-poor, low-surface brightness galaxy (i.e., $M_{g}$ = $-$14.5 mag). Our photometric analysis reveals that SN 2016ije is subluminous ($M_{B,\rm{max}}$ = $-$17.65$\pm$0.06 mag) but exhibits relatively broad light curves (${\Delta}m_{15}(B)$ = 1.35$\pm$0.14 mag), similar to the behavior of SN 2002es. Our analysis of the bolometric light curve indicates that only 0.14$\pm$0.04 $M_{\odot}$ of $^{56}$Ni was synthesized in the explosion of SN 2016ije, which suggests a less energetic thermonuclear explosion when compared to normal SNe Ia, and this left a considerable amount of unburned materials in the ejecta. Spectroscopically, SN 2016ije resembles other SN 2002es-like SNe Ia, except that the ejecta velocity inferred from its carbon absorption line ($\sim$ 4500 km s$^{-1}$) is much lower than that from silicon lines ($\sim$ 8300 km s$^{-1}$) at around the maximum light. Additionally, most of the absorption lines are broader than other 02es-like SNe Ia. These peculiarities suggest the presence of significant unburned carbon in the inner region and a wide line-forming region along the line of sight. These characteristics suggest that SN 2016ije might originate from the violent merger of a white dwarf binary system, when viewed near an orientation along the iron-group-element cavity caused by the companion star.Comment: 25 pages, 13 figure

A Systematic Study of Ia-CSM Supernovae from the ZTF Bright Transient Survey

International audienceAmong the supernovae (SNe) that show strong interaction with the circumstellar medium, there is a rare subclass of Type Ia supernovae, SNe Ia-CSM, that show strong narrow hydrogen emission lines much like SNe IIn but on top of a diluted over-luminous Type Ia spectrum. In the only previous systematic study of this class (Silverman et al. 2013), 16 objects were identified, 8 historic and 8 from the Palomar Transient Factory (PTF). Now using the successor survey to PTF, the Zwicky Transient Facility (ZTF), we have classified 12 additional objects of this type through the systematic Bright Transient Survey (BTS). In this study, we present and analyze the optical and mid-IR light curves, optical spectra, and host galaxy properties of this sample. Consistent with previous studies, we find the objects to have slowly evolving light curves compared to normal SNe Ia with peak absolute magnitudes between -19.1 and -21, spectra having weak H$\beta$, large Balmer decrements of ~7 and strong Ca NIR emission. Out of 10 SNe from our sample observed by NEOWISE, 9 have $3\sigma$ detections, along with some showing a clear reduction in red-wing of H$\alpha$, indicative of newly formed dust. We do not find our SN Ia-CSM sample to have a significantly different distribution of equivalent width of He I $\lambda5876$ than SNe IIn as observed in Silverman et al. 2013. The hosts tend to be late-type galaxies with recent star formation. We also derive a rate estimate of 29$^{+27}_{-21}$ Gpc$^{-3}$ yr$^{-1}$ for SNe Ia-CSM which is ~0.02--0.2 % of the SN Ia rate. This work nearly doubles the sample of well-studied Ia-CSM objects in Silverman et al. 2013, increasing the total number to 28