The Foundation Supernova Survey: Photospheric Velocity Correlations in Type Ia Supernovae

Dettman, Kyle G.; Jha, Saurabh W.; Dai, Mi; Foley, Ryan J.; Rest, Armin; Scolnic, Daniel M.; Siebert, Matthew R.; Chambers, K. C.; Coulter, D. A.; Huber, M. E.; Johnson, E.; Jones, D. O.; Kilpatrick, C. D.; Kirshner, R. P.; Pan, Y. -C.; Riess, A. G.; Schultz, A. S. B.

doi:10.48550/arxiv.2102.06524

Cited by 4 publications

(5 citation statements)

References 42 publications

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“…Clearly the values here are very consistent with C11 intrinsic scatter model values reported from past surveys, while the the consistency with G10 scatter model based analyses is at the level of < 2𝜎. Finally, we show the comparison with a determination of 𝛽 from 69 low redshift SN Ia (Dettman et al 2021) from the Foundation Supernova Survey (Foley et al 2018). ).…”

Section: Consistency Of 𝛽 Constraints With Previously Reported Valuessupporting

confidence: 89%

“…The constraints are 𝛽 = 3.4(3.6) ± 0.3 (0.4). The shaded vertical rectangles show the 1 − 𝜎 constraint on 𝛽 from the PanSTARRS spectroscopic sample(Scolnic et al 2018) for the G10 model of intrinsic scatter (red) and the C11 model (blue) and for 69 low redshift SN Ia from the Foundation Supernova Survey (yellow)(Dettman et al 2021). The hatched red region shows the probability of the 𝛽 value being at least as large as the value expected if the colour dependent extinction was solely due to ISM host dust of the same nature as the Milky Way.…”

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confidence: 99%

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Two c's in a pod: Cosmology independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair

Biswas,

Goobar,

Dhawan

et al. 2021

Preprint

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Using Zwicky Transient Facility (ZTF) observations, we identify a pair of "sibling" Type Ia supernovae (SNe Ia), i.e., hosted by the same galaxy at 𝑧 = 0.0541. They exploded within 200 days from each other at a separation of 0.6 corresponding to a projected distance of only 0.6 kpc. Performing SALT2 light curve fits to the 𝑔𝑟𝑖 ZTF photometry, we show that for these equally distant 'standardizable candles", there is a difference of 2 magnitudes in their rest frame 𝐵-band peaks, and the fainter SN has a significantly red SALT2 colour 𝑐 = 0.57 ± 0.04, while the stretch values 𝑥 1 of the two SNe are similar, suggesting that the fainter SN is attenuated by dust in the interstellar medium of the host galaxy. We use these measurements to infer the SALT2 colour standardization parameter, 𝛽 = 3.5±0.3, independent of the underlying cosmology and Malmquist bias. Assuming the colour excess is entirely due to dust, the result differs by 2𝜎 from the average Milky-Way total-to-selective extinction ratio, but is in good agreement with the colour-brightness corrections empirically derived from the most recent SN Ia Hubble-Lemaitre diagram fits. Thus we suggest that SN "siblings", which will increasingly be discovered in the coming years, can be used to probe the validity of the colour and lightcurve shape corrections using in SN Ia cosmology while avoiding important systematic effects in their inference from global multi-parameter fits to inhomogeneous data-sets, and also help constrain the role of interstellar dust in SN Ia cosmology.

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Section: Consistency Of 𝛽 Constraints With Previously Reported Valuessupporting

confidence: 89%

mentioning

confidence: 99%

Two c's in a pod: Cosmology independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair

Biswas,

Goobar,

Dhawan

et al. 2021

Preprint

View full text Add to dashboard Cite

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“…Incorporation of spectroscopic indicators of intrinsic colour (e.g. ejecta velocity, Foley & Kasen 2011;Mandel et al 2014;Dettman et al 2021) may provide additional insight. We are working to carefully merge the present SED model with that of M20 extending through NIR 𝐻-band, and also to extend it to the ultraviolet.…”

Section: The Bmentioning

confidence: 99%

Testing the Consistency of Dust Laws in SN Ia Host Galaxies: A BayeSN Examination of Foundation DR1

Thorp,

Mandel,

Jones

et al. 2021

Preprint

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We apply B SN, our new hierarchical Bayesian model for the SEDs of Type Ia supernovae (SNe Ia), to analyse the 𝑔𝑟𝑖𝑧 light curves of 157 nearby SNe Ia (0.015 < 𝑧 < 0.08) from the public Foundation DR1 dataset. We train a new version of B SN, continuous from 0.35-0.95 μm, which we use to model the properties of SNe Ia in the rest-frame 𝑧-band, study the properties of dust in their host galaxies, and construct a Hubble diagram of SN Ia distances determined from full 𝑔𝑟𝑖𝑧 light curves. Our 𝑔𝑟𝑖𝑧 Hubble diagram has a low total RMS of 0.13 mag using B SN, compared to 0.16 mag using SALT2. Additionally, we test the consistency of the dust law 𝑅 𝑉 between low-and high-mass host galaxies by using our model to fit the full time-and wavelength-dependent SEDs of SNe Ia up to moderate reddening (peak apparent 𝐵 − 𝑉 0.3). Splitting the population at the median host mass, we find 𝑅 𝑉 = 2.84 ± 0.31 in low-mass hosts, and 𝑅 𝑉 = 2.58 ± 0.23 in high-mass hosts, both consistent with the global value of 𝑅 𝑉 = 2.61 ± 0.21 that we estimate for the full sample. For all choices of mass split we consider, 𝑅 𝑉 is consistent across the step within 1.2𝜎. Modelling population distributions of dust laws in low-and high-mass hosts, we find that both subsamples are highly consistent with the full sample's population mean 𝜇(𝑅 𝑉 ) = 2.70 ± 0.25 with a 95% upper bound on the population 𝜎(𝑅 𝑉 ) < 0.61. The 𝑅 𝑉 population means are consistent within 1.2𝜎. We find that simultaneous fitting of host-mass-dependent dust properties within our hierarchical model does not account for the conventional mass step.

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“…The iz band coverage of Foundation is particularly critical to creating a SALT3 model that is trained to redder wavelengths than enabled by the JLA data alone. We include spectra for 114 Foundation SNe from the Dettman et al (2021) data release.…”

Section: The Foundation Supernova Surveymentioning

confidence: 99%

SALT3: An Improved Type Ia Supernova Model for Measuring Cosmic Distances

Kenworthy,

Jones,

Dai

et al. 2021

Preprint

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A spectral-energy distribution (SED) model for Type Ia supernovae (SNe Ia) is a critical tool for measuring precise and accurate distances across a large redshift range and constraining cosmological parameters. We present an improved model framework, SALT3, which has several advantages over current models including the leading SALT2 model (SALT2.4). While SALT3 has a similar philosophy, it differs from SALT2 by having improved estimation of uncertainties, better separation of color and light-curve stretch, and a publicly available training code. We present the application of our training method on a cross-calibrated compilation of 1083 SNe with 1207 spectra. Our compilation is 2.5× larger than the SALT2 training sample and has greatly reduced calibration uncertainties. The resulting trained SALT3.K21 model has an extended wavelength range 2000-11000 Å (1800 Å redder) and reduced uncertainties compared to SALT2, enabling accurate use of low-z I and iz photometric bands. Including these previously discarded bands, SALT3.K21 reduces the Hubble scatter of the low-z Foundation and CfA3 samples by 15% and 10%, respectively. To check for potential systematic uncertainties we compare distances of low (0.01 < z < 0.2) and high (0.4 < z < 0.6) redshift SNe in the training compilation, finding an insignificant 2 ± 14 mmag shift between SALT2.4 and SALT3.K21. While the SALT3.K21 model was trained on optical data, our method can be used to build a model for rest-frame NIR samples from the Roman Space Telescope. Our open-source training code, public training data, model, and documentation are available at https://saltshaker.readthedocs.io/en/latest/, and the model is integrated into the sncosmo and SNANA software packages.

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The Foundation Supernova Survey: Photospheric Velocity Correlations in Type Ia Supernovae

Cited by 4 publications

References 42 publications

Two c's in a pod: Cosmology independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair

Two c's in a pod: Cosmology independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair

Testing the Consistency of Dust Laws in SN Ia Host Galaxies: A BayeSN Examination of Foundation DR1

SALT3: An Improved Type Ia Supernova Model for Measuring Cosmic Distances

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