| 1. |
- Camacho-Neves, Yssavo, et al.
(författare)
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Over 500 Days in the Life of the Photosphere of the Type Iax Supernova SN 2014dt
- 2023
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 951:1
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Tidskriftsartikel (refereegranskat)abstract
- Type Iax supernovae (SNe Iax) are the largest known class of peculiar white dwarf SNe, distinct from normal Type Ia supernovae (SNe Ia). The unique properties of SNe Iax, especially their strong photospheric lines out to extremely late times, allow us to model their optical spectra and derive the physical parameters of the long-lasting photosphere. We present an extensive spectral timeseries, including 21 new spectra, of SN Iax 2014dt from +11 to +562 days after maximum light. We are able to reproduce the entire timeseries with a self-consistent, nearly unaltered deflagration explosion model from Fink et al. using TARDIS, an open source radiative-transfer code. We find that the photospheric velocity of SN 2014dt slows its evolution between +64 and +148 days, which closely overlaps the phase when we see SN 2014dt diverge from the normal spectral evolution of SNe Ia (+90 to +150 days). The photospheric velocity at these epochs, ∼400–1000 km s−1, may demarcate a boundary within the ejecta below which the physics of SNe Iax and normal SNe Ia differ. Our results suggest that SN 2014dt is consistent with a weak deflagration explosion model that leaves behind a bound remnant and drives an optically thick, quasi-steady-state wind creating the photospheric lines at late times. The data also suggest that this wind may weaken at epochs past +450 days, perhaps indicating a radioactive power source that has decayed away.
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| 2. |
- Dimitriadis, Georgios, et al.
(författare)
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SN 2021zny : an early flux excess combined with late-time oxygen emission suggests a double white dwarf merger event
- 2023
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 521:1, s. 1162-1183
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Tidskriftsartikel (refereegranskat)abstract
- We present a photometric and spectroscopic analysis of the ultraluminous and slowly evolving 03fg-like Type Ia SN 2021zny. Our observational campaign starts from similar to 5.3 h after explosion (making SN 2021zny one of the earliest observed members of its class), with dense multiwavelength coverage from a variety of ground-and space-based telescopes, and is concluded with a nebular spectrum similar to 10 months after peak brightness. SN 2021zny displayed several characteristics of its class, such as the peak brightness (M-B = -19.95 mag), the slow decline (delta m(15)(B) = 0.62 mag), the blue early-time colours, the low ejecta velocities, and the presence of significant unburned material above the photosphere. However, a fluxexcess for the first similar to 1.5 d after explosion is observed in four photometric bands, making SN 2021zny the third 03fg-like event with this distinct behaviour, while its + 313 d spectrum shows prominent [OI] lines, a very unusual characteristic of thermonuclear SNe. The early flux excess can be explained as the outcome of the interaction of the ejecta with similar to 0 . 04 M-? of H/He-poor circumstellar material at a distance of similar to 10(12) cm, while the low ionization state of the late-time spectrum re veals lo w abundances of stable iron-peak elements. All our observations are in accordance with a progenitor system of two carbon/oxygen white dwarfs that undergo a merger event, with the disrupted white dwarf ejecting carbon-rich circumstellar material prior to the primary white dwarf detonation.
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| 3. |
- Galbany, L., et al.
(författare)
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An updated measurement of the Hubble constant from near-infrared observations of Type Ia supernovae
- 2023
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 679
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the Hubble constant (H0) using type Ia supernovae (SNe Ia) in the near-infrared (NIR) from the recently updated sample of SNe Ia in nearby galaxies with distances measured via Cepheid period-luminosity relations by the SH0ES project. We collected public near-infrared photometry of up to 19 calibrator SNe Ia and 57 SNe Ia in the Hubble flow (z > 0.01), and directly measured their peak magnitudes in the J- and H-band by Gaussian processes and spline interpolation. Calibrator peak magnitudes together with Cepheid-based distances were used to estimate the average absolute magnitude in each band, while Hubble-flow SNe were used to constrain the zero-point intercept of the magnitude–redshift relation. Our baseline result of H0 is 72.3 ± 1.4 (stat) ±1.4 (syst) km s−1 Mpc−1 in the J-band and 72.3 ± 1.3 (stat) ±1.4 (syst) km s−1 Mpc−1 in the H-band, where the systematic uncertainties include the standard deviation of up to 21 variations of the analysis, the 0.7% distance scale systematic from SH0ES Cepheid anchors, a photometric zero-point systematic, and a cosmic variance systematic. Our final measurement represents a measurement with a precision of 2.8% in both bands. Among all the analysis variants, the largest change in H0 comes from limiting the sample to those SNe from the CSP and CfA programs; they are noteworthy because they are the best calibrated, yielding H0 ∼ 75 km s−1 Mpc−1 in both bands. We explore applying stretch and reddening corrections to standardize SN Ia NIR peak magnitudes, and we demonstrate that they are still useful to reduce the absolute magnitude scatter and, which improves its standardization, at least up to the H-band. Based on our results, in order to improve the precision of the H0 measurement with SNe Ia in the NIR in the future, we would need to increase the number of calibrator SNe Ia, to be able to extend the Hubble–Lemaître diagram to higher redshift, and to include standardization procedures to help reduce the NIR intrinsic scatter.
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| 4. |
- Goobar, Ariel, 1962-, et al.
(författare)
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Uncovering a population of gravitational lens galaxies with magnified standard candle SN Zwicky
- 2023
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Ingår i: Nature Astronomy. - 2397-3366. ; 7:9, s. 1098-1107
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Tidskriftsartikel (refereegranskat)abstract
- Detecting gravitationally lensed supernovae is among the biggest challenges in astronomy. It involves a combination of two very rare phenomena: catching the transient signal of a stellar explosion in a distant galaxy and observing it through a nearly perfectly aligned foreground galaxy that deflects light towards the observer. Here we describe how high-cadence optical observations with the Zwicky Transient Facility, with its unparalleled large field of view, led to the detection of a multiply imaged type Ia supernova, SN Zwicky, also known as SN 2022qmx. Magnified nearly 25-fold, the system was found thanks to the standard candle nature of type Ia supernovae. High-spatial-resolution imaging with the Keck telescope resolved four images of the supernova with very small angular separation, corresponding to an Einstein radius of only θE = 0.167″ and almost identical arrival times. The small θE and faintness of the lensing galaxy are very unusual, highlighting the importance of supernovae to fully characterize the properties of galaxy-scale gravitational lenses, including the impact of galaxy substructures.
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| 5. |
- Kool, Erik C., et al.
(författare)
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A radio-detected type Ia supernova with helium-rich circumstellar material
- 2023
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 617:7961, s. 477-482
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Tidskriftsartikel (refereegranskat)abstract
- Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf stars destabilized by mass accretion from a companion star1, but the nature of their progenitors remains poorly understood. A way to discriminate between progenitor systems is through radio observations; a non-degenerate companion star is expected to lose material through winds2 or binary interaction3 before explosion, and the supernova ejecta crashing into this nearby circumstellar material should result in radio synchrotron emission. However, despite extensive efforts, no type Ia supernova (SN Ia) has ever been detected at radio wavelengths, which suggests a clean environment and a companion star that is itself a degenerate white dwarf star4,5. Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich circumstellar material, as demonstrated by its spectral features, infrared emission and, for the first time in a SN Ia to our knowledge, a radio counterpart. On the basis of our modelling, we conclude that the circumstellar material probably originates from a single-degenerate binary system in which a white dwarf accretes material from a helium donor star, an often proposed formation channel for SNe Ia (refs. 6,7). We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems.
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| 6. |
- Liu, Chang, et al.
(författare)
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SN 2022joj : A Peculiar Type Ia Supernova Possibly Driven by an Asymmetric Helium-shell Double Detonation
- 2023
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 958:2
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Tidskriftsartikel (refereegranskat)abstract
- We present observations of SN 2022joj, a peculiar Type Ia supernova discovered by the Zwicky Transient Facility. SN 2022joj exhibits an unusually red g ZTF - r ZTF color at early times and a rapid blueward evolution afterward. Around maximum brightness, SN 2022joj shows a high luminosity ( MgZTF,max similar or equal to-19.7 mag), a blue broadband color (g ZTF - r ZTF similar or equal to -0.2 mag), and shallow Si ii absorption lines, consistent with those of overluminous, SN 1991T-like events. The maximum-light spectrum also shows prominent absorption around 4200 angstrom, which resembles the Ti ii features in subluminous, SN 1991bg-like events. Despite the blue optical-band colors, SN 2022joj exhibits extremely red ultraviolet minus optical colors at maximum luminosity (u - v similar or equal to 0.6 mag and uvw1 - v similar or equal to 2.5 mag), suggesting a suppression of flux at similar to 2500-4000 angstrom. Strong C ii lines are also detected at peak. We show that these unusual spectroscopic properties are broadly consistent with the helium-shell double detonation of a sub-Chandrasekhar mass (M similar or equal to 1 M circle dot) carbon/oxygen white dwarf from a relatively massive helium shell (M s similar or equal to 0.04-0.1 M circle dot), if observed along a line of sight roughly opposite to where the shell initially detonates. None of the existing models could quantitatively explain all the peculiarities observed in SN 2022joj. The low flux ratio of [Ni ii] lambda 7378 to [Fe ii] lambda 7155 emission in the late-time nebular spectra indicates a low yield of stable Ni isotopes, favoring a sub-Chandrasekhar mass progenitor. The significant blueshift measured in the [Fe ii] lambda 7155 line is also consistent with an asymmetric chemical distribution in the ejecta, as is predicted in double-detonation models.
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| 7. |
- Pierel, J. D. R., et al.
(författare)
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LensWatch. I. Resolved HST Observations and Constraints on the Strongly Lensed Type Ia Supernova 2022qmx (SN Zwicky)
- 2023
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 948:2
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Tidskriftsartikel (refereegranskat)abstract
- Supernovae (SNe) that have been multiply imaged by gravitational lensing are rare and powerful probes for cosmology. Each detection is an opportunity to develop the critical tools and methodologies needed as the sample of lensed SNe increases by orders of magnitude with the upcoming Vera C. Rubin Observatory and Nancy Grace Roman Space Telescope. The latest such discovery is of the quadruply imaged Type Ia SN 2022qmx (aka, SN Zwicky) at z = 0.3544. SN Zwicky was discovered by the Zwicky Transient Facility in spatially unresolved data. Here we present follow-up Hubble Space Telescope observations of SN Zwicky, the first from the multicycle LensWatch (www.lenswatch.org) program. We measure photometry for each of the four images of SN Zwicky, which are resolved in three WFC3/UVIS filters (F475W, F625W, and F814W) but unresolved with WFC3/IR F160W, and present an analysis of the lensing system using a variety of independent lens modeling methods. We find consistency between lens-model-predicted time delays (less than or similar to 1 day), and delays estimated with the single epoch of Hubble Space Telescope colors (less than or similar to 3.5 days), including the uncertainty from chromatic microlensing (similar to 1-1.5 days). Our lens models converge to an Einstein radius of theta(E) = 0.168 (+0.009)(-0.005) the smallest yet seen in a lensed SN system. The standard candle nature of SN Zwicky provides magnification estimates independent of the lens modeling that are brighter than predicted by similar to 1.7 (-0.6) (+0.8) mag and similar to 0.9 (-0.6) (+0.8) mag for two of the four images, suggesting significant microlensing and/or additional substructure beyond the flexibility of our image-position mass models.
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| 8. |
- Shahbandeh, Melissa, et al.
(författare)
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JWST observations of dust reservoirs in type IIP supernovae 2004et and 2017eaw
- 2023
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Ingår i: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 523:4, s. 6048-6060
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Tidskriftsartikel (refereegranskat)abstract
- Supernova (SN) explosions have been sought for decades as a possible source of dust in the Universe, providing the seeds of galaxies, stars, and planetary systems. SN 1987A offers one of the most promising examples of significant SN dust formation, but until the James Webb Space Telescope (JWST), instruments have traditionally lacked the sensitivity at both late times (>1 yr post-explosion) and longer wavelengths (i.e. >10 μm) to detect analogous dust reservoirs. Here we present JWST/MIRI observations of two historic Type IIP SNe, 2004et and SN 2017eaw, at nearly 18 and 5 yr post-explosion, respectively. We fit the spectral energy distributions as functions of dust mass and temperature, from which we are able to constrain the dust geometry, origin, and heating mechanism. We place a 90 per cent confidence lower limit on the dust masses for SNe 2004et and 2017eaw of >0.014 and >4 × 10−4 M⊙, respectively. More dust may exist at even colder temperatures or may be obscured by high optical depths. We conclude dust formation in the ejecta to be the most plausible and consistent scenario. The observed dust is radiatively heated to ∼100–150 K by ongoing shock interaction with the circumstellar medium. Regardless of the best fit or heating mechanism adopted, the inferred dust mass for SN 2004et is the second highest (next to SN 1987A) mid-infrared inferred dust mass in extragalactic SNe thus far, promoting the prospect of SNe as potential significant sources of dust in the Universe.
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| 9. |
- Sharma, Yashvi, et al.
(författare)
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A Systematic Study of Ia-CSM Supernovae from the ZTF Bright Transient Survey
- 2023
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 948:1
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Tidskriftsartikel (refereegranskat)abstract
- Among the supernovae (SNe) that show strong interaction with a circumstellar medium (CSM), there is a rare subclass of Type Ia supernovae, SNe Ia-CSM, which show strong narrow hydrogen emission lines much like SNe IIn but on top of a diluted Type Ia spectrum. The only previous systematic study of this class identified 16 SNe Ia-CSM, eight historic and eight from the Palomar Transient Factory (PTF). Now using the successor survey to PTF, the Zwicky Transient Facility (ZTF), we have classified 12 additional SNe Ia-CSM through the systematic Bright Transient Survey (BTS). Consistent with previous studies, we find these SNe to have slowly evolving optical light curves with peak absolute magnitudes between -19.1 and -21, spectra having weak H ss and large Balmer ldecrements of similar to 7. Out of the 10 SNe from our sample observed by NEOWISE, nine have 3 sigma detections, with some SNe showing a reduction in the red wing of Ha, indicative of newly formed dust. We do not find our SN Ia-CSM sample to have a significantly different distribution of equivalent widths of He I.5876 than SNe IIn as observed in Silverman et al. The hosts tend to be late-type galaxies with recent star formation. We derive a rate estimate of 29+(27)(21) Gpc(-3) yr(-1) for SNe Ia-CSM, which is similar to 0.02%-0.2% of the SN Ia rate. We also identify six ambiguous SNe IIn/Ia-CSM in the BTS sample and including them gives an upper limit rate of 0.07%-0.8%. This work nearly doubles the sample of well-studied Ia-CSM objects in Silverman et al., increasing the total number to 28.
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