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

A kilometer-scale asteroid inside Venus's orbit

Near-Earth asteroid population models predict the existence of asteroids located inside the orbit of Venus. However, despite searches up to the end of 2019, none have been found. Here we report the discovery by the Zwicky Transient Facility of the first known asteroid located inside of Venus' orbit, 2020 AV₂, possessing an aphelion distance of 0.65 au and ∼2 km in size. While it is possible that 2020 AV₂ is the largest of its kind, we find that its discovery is surprising in the context of population models where the expected count is close to zero. If this discovery is not a statistical fluke, then 2020 AV₂ may come from a yet undiscovered source population of asteroids interior to Venus, and currently favored asteroid population models may need to be adjusted

A kilometer-scale asteroid inside Venus's orbit

Near-Earth asteroid population models predict the existence of asteroids located inside the orbit of Venus. However, despite searches up to the end of 2019, none have been found. Here we report the discovery by the Zwicky Transient Facility of the first known asteroid located inside of Venus' orbit, 2020 AV₂, possessing an aphelion distance of 0.65 au and ∼2 km in size. While it is possible that 2020 AV₂ is the largest of its kind, we find that its discovery is surprising in the context of population models where the expected count is close to zero. If this discovery is not a statistical fluke, then 2020 AV₂ may come from a yet undiscovered source population of asteroids interior to Venus, and currently favored asteroid population models may need to be adjusted

The tidal disruption event AT2021ehb: evidence of relativistic disk reflection, and rapid evolution of the disk-corona system

High Energy Astrophysic

Deliver us from Evil: The Effects of Mortality Salience and Reminders of 9/11 on Support for President George W. Bush

According to terror management theory, heightened concerns about mortality should intensify the appeal of charismatic leaders. To assess this idea, we investigated how thoughts about death and the 9/11 terrorist attacks influence Americans’ attitudes toward current U.S. President George W. Bush. Study 1 found that reminding people of their own mortality (mortality salience) increased support for Bush and his counterterrorism policies. Study 2 demonstrated that subliminal exposure to 9/11-related stimuli brought death-related thoughts closer to consciousness. Study 3 showed that reminders of both mortality and 9/11 increased support for Bush. In Study 4, mortality salience led participants to become more favorable toward Bush and voting for him in the upcoming election but less favorable toward Presidential candidate John Kerry and voting for him. Discussion focused on the role of terror management processes in allegiance to charismatic leaders and political decision making.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Religious Diversity and Conceptual Schemes: Critically Appraising Internalist Pluralism

Is a philosophical theory needed to ‘underwrite’ attitudes of toleration and respect in a multicultural and religiously diverse world? Many philosophers of religion have thought so, including Victoria Harrison. This article interrogates Harrison’s theory of internalist pluralism, which, though offering a welcome alternative to other theories, such as John Hick’s ‘pluralistic hypothesis’, nevertheless faces problems. Questioning the coherence of the theory’s account of how the existence of objects of worship can avoid being fully conceptual-scheme dependent, and raising doubts about its pretensions to promote interreligious harmony, I also critically discuss the common philosophical tendency to work with under-described and insufficiently analysed examples. What philosophy ought to be able to offer in relation to religious diversity, I propose, is attentiveness to nuances and particularities, thereby aiding religious understanding without the need for a general theory

Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy

We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD2 taken with Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3), Spitzer Space Telescope/Infrared Array Camera (Spitzer/IRAC), and the GROWTH telescope network, visible spectroscopy from Keck/Low-Resolution Imaging Spectrometer (LRIS), and archival Zwicky Transient Facility observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD2 has a radius between 0.2 and 1.8 km assuming a 0.08 albedo and a coma dominated by ∼100 μm-scale dust ejected at ∼1 m s−1 speeds with a ∼1′ jet pointing in the southwest direction. LD2 experienced a total dust mass loss of ∼108 kg at a loss rate of ∼6 kg s−1 with Afρ/cross section varying between ∼85 cm/125 km2 and ∼200 cm/310 km2 from 2019 April 9 to 2019 November 8. If the increase in Afρ/cross section remained constant, it implies LD2's activity began ∼2018 November when within 4.8 au of the Sun, implying the onset of H2O sublimation. We measure CO/CO2 gas production of ≲1027 mol s−1/≲1026 mol s−1 from our 4.5 μm Spitzer observations; g–r = 0.59 ± 0.03, r–i = 0.18 ± 0.05, and i–z = 0.01 ± 0.07 from GROWTH observations; and H2O gas production of ≲80 kg s−1 scaling from our estimated C2 production of ${Q}_{{C}_{2}}\lesssim 7.5\times {10}^{24}$ mol s−1 from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD2 is similar to Jupiter-family comets having close encounters with Jupiter within ∼0.5 Hill radius in the last ∼3 y and within 0.8 Hill radius in ∼9 y. Additionally, 78.8% of our orbital clones are ejected from the solar system within 1 × 106 yr, having a dynamical half-life of 3.4 × 105 yr

Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF

We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of Hr = 14.63 ± 0.02, Gr = 0.21 ± 0.02 from our secular phase-curve observations. In addition, we were able to constrain Gault's rotation period using time-series photometric lightcurves taken over 17 hr on multiple days in 2020 August, September, and October. The photometric lightcurves have a repeating ≲0.05 mag feature suggesting that (6478) Gault has a rotation period of ∼2.5 hr and may have a semispherical or top-like shape, much like the near-Earth asteroids Ryugu and Bennu. The rotation period of ∼2.5 hr is near the expected critical rotation period for an asteroid with the physical properties of (6478) Gault, suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spin-up by the Yarkovsky–O'Keefe–Radzievskii–Paddack effect