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1. Cosmological Results from the RAISIN Survey: Using Type Ia Supernovae in the Near Infrared as a Novel Path to Measure the Dark Energy Equation of State

   https://doi.org/10.3847/1538-4357/ac755b  

   Jones, D. O. ; Mandel, K. S. ; Kirshner, R. P. ; Thorp, S. ; Challis, P. M. ; Avelino, A. ; Brout, D. ; Burns, C. ; Foley, R. J. ; Pan, Y. -C. ; et al ( July 2022 , The Astrophysical Journal)

   Type Ia supernovae (SNe Ia) are more precise standardizable candles when measured in the near-infrared (NIR) than in the optical. With this motivation, from 2012 to 2017 we embarked on the RAISIN program with the Hubble Space Telescope (HST) to obtain rest-frame NIR light curves for a cosmologically distant sample of 37 SNe Ia (0.2 ≲z≲ 0.6) discovered by Pan-STARRS and the Dark Energy Survey. By comparing higher-zHST data with 42 SNe Ia atz< 0.1 observed in the NIR by the Carnegie Supernova Project, we construct a Hubble diagram from NIR observations (with only time of maximum light and some selection cuts from optical photometry) to pursue a unique avenue to constrain the dark energy equation-of-state parameter,w. We analyze the dependence of the full set of Hubble residuals on the SN Ia host galaxy mass and find Hubble residual steps of size ∼0.06-0.1 mag with 1.5σ−2.5σsignificance depending on the method and step location used. Combining our NIR sample with cosmic microwave background constraints, we find 1 +w= −0.17 ± 0.12 (statistical + systematic errors). The largest systematic errors are the redshift-dependent SN selection biases and the properties of the NIR mass step. We also use these data to measureH₀= 75.9 ± 2.2 km s⁻¹Mpc⁻¹from stars with geometric distance calibration in the hosts of eight SNe Ia observed in the NIR versusH₀= 71.2 ± 3.8 km s⁻¹Mpc⁻¹using an inverse distance ladder approach tied to Planck. Using optical data, we find 1 +w= −0.10 ± 0.09, and with optical and NIR data combined, we find 1 +w= −0.06 ± 0.07; these shifts of up to ∼0.11 inwcould point to inconsistency in the optical versus NIR SN models. There will be many opportunities to improve this NIR measurement and better understand systematic uncertainties through larger low-zsamples, new light-curve models, calibration improvements, and eventually by building high-zsamples from the Roman Space Telescope.

    

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2. Examining the Properties of Low-luminosity Hosts of Type Ia Supernovae from ASAS-SN

   https://doi.org/10.3847/1538-4357/acce35  

   Holoien, Thomas W. -S. ; Berger, Vera L. ; Hinkle, Jason T. ; Galbany, L. ; Strom, Allison L. ; Vallely, Patrick J. ; Anderson, Joseph P. ; Boutsia, Konstantina ; French, K. D. ; Kochanek, Christopher S. ; et al ( June 2023 , The Astrophysical Journal)

   We present a spectroscopic analysis of 44 low-luminosity host galaxies of Type Ia supernovae (SNe Ia) detected by the All-Sky Automated Survey for Supernovae (ASAS-SN), using hydrogen, oxygen, and sulfur emission lines to measure metallicities and star formation rates. We find no statistically significant evidence that the star formation activity and metallicities of the galaxies in our sample are inconsistent with galaxies of similar luminosities and masses. We identify two 3σoutlier galaxies that have high metallicities for their stellar masses, but find that their other properties are consistent with general galaxies. The overall consistency between our sample and general galaxy samples further strengthens the evidence from more luminous SN Ia host galaxy samples that SN Ia host galaxies are typical.

    

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3. The ASAS-SN bright supernova catalogue – V. 2018–2020

   https://doi.org/10.1093/mnras/stad355  

   Neumann, K. D. ; Holoien, T. W-S ; Kochanek, C. S. ; Stanek, K. Z. ; Vallely, P. J. ; Shappee, B. J. ; Prieto, J. L. ; Pessi, T. ; Jayasinghe, T. ; Brimacombe, J. ; et al ( February 2023 , Monthly Notices of the Royal Astronomical Society)

   We catalogue the 443 bright supernovae (SNe) discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) in 2018−2020 along with the 519 SNe recovered by ASAS-SN and 516 additional mpeak ≤ 18 mag SNe missed by ASAS-SN. Our statistical analysis focuses primarily on the 984 SNe discovered or recovered in ASAS-SN g-band observations. The complete sample of 2427 ASAS-SN SNe includes earlier V-band samples and unrecovered SNe. For each SN, we identify the host galaxy, its UV to mid-IR photometry, and the SN’s offset from the centre of the host. Updated peak magnitudes, redshifts, spectral classifications, and host galaxy identifications supersede earlier results. With the increase of the limiting magnitude to g ≤ 18 mag, the ASAS-SN sample is nearly complete up to mpeak = 16.7 mag and is 90 per cent complete for mpeak ≤ 17.0 mag. This is an increase from the V-band sample, where it was roughly complete up to mpeak = 16.2 mag and 70 per cent complete for mpeak ≤ 17.0 mag.

    

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4. Late-onset Circumstellar Medium Interactions are Rare: An Unbiased GALEX View of Type Ia Supernovae

   https://doi.org/10.3847/1538-4357/ac3bb4  

   Dubay, Liam O. ; Tucker, Michael A. ; Do, Aaron ; Shappee, Benjamin J. ; Anand, Gagandeep S. ( February 2022 , The Astrophysical Journal)

   Using ultraviolet (UV) light curves, we constrain the circumstellar environments of 1080 Type Ia supernovae (SNe Ia) withinz< 0.5 from archival Galaxy Evolution Explorer (GALEX) observations. All SNe Ia are required to have pre- and post-explosion GALEX observations to ensure adequate subtraction of the host-galaxy flux. Using the late-time GALEX observations, we look for the UV excess expected from any interaction between the SN ejecta and circumstellar material (CSM). Four SNe Ia are detected near maximum light, and we compare the GALEX photometry to archival data. However, we find that none of our targets show convincing evidence of CSM interaction. A recent Hubble Space Telescope (HST) survey estimates that ∼6% of SNe Ia may interact with distant CSM, but statistical inferences are complicated by the small sample size and selection effects. By injecting model light curves into our data and then recovering them, we constrain a broad range of CSM interactions based on the CSM interaction start time and the maximum luminosity. Combining our GALEX nondetections with the HST results, we constrain occurrence of late-onset CSM interaction among SNe Ia with moderate CSM interaction, similar to that observed in PTF11kx, tof_CSM≲ 5.1% between 0 and 500 days after discovery and ≲2.7% between 500 and 1000 days after discovery at 90% confidence. For weaker CSM interactions similar to SN 2015cp, we obtain limits of ≲16% and ≲4.8%, respectively, for the same time ranges.

    

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5. Environmental Dependence of Type Ia Supernovae in Low-redshift Galaxy Clusters

   https://doi.org/10.3847/1538-4357/ad0e0f  

   Larison, Conor ; Jha, Saurabh W. ; Kwok, Lindsey A. ; Camacho-Neves, Yssavo ( January 2024 , The Astrophysical Journal)

   We present an analysis of 102 Type Ia supernovae (SNe Ia) in nearby (z< 0.1), x-ray-selected galaxy clusters. This is the largest such sample to date and is based on archival data primarily from ZTF and ATLAS. We divide our SNe Ia into an inner cluster sample projected withinr₅₀₀of the cluster center and an outer cluster sample projected betweenr₅₀₀and 2r₅₀₀. We compare these to field samples of SNe Ia at similar redshifts in both quiescent and star-forming host galaxies. Based on SALT3 fits to the light curves, we find that the inner cluster SNe Ia have a higher fraction of fast-evolving objects (SALT3x₁< −1) than the outer cluster or field quiescent samples. This implies an intrinsically different population of SNe Ia occurs in inner cluster environments, beyond known correlations based on host galaxy alone. Our cluster samples show a strongly bimodalx₁distribution with a fast-evolving component that dominates the inner cluster objects (≳75%) but is just a small fraction of SNe Ia in field star-forming galaxies (≲10%). We do not see strong evidence for variations in the color (SALT3c) distributions among the samples and find only minor differences in SN Ia standardization parameters and Hubble residuals. We suggest that the age of the stellar population drives the observed distributions, with the oldest populations nearly exclusively producing fast-evolving SNe Ia.

    

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