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

2021 ◽  
Vol 923 (2) ◽  
pp. 267
Author(s):  
Kyle G. Dettman ◽  
Saurabh W. Jha ◽  
Mi Dai ◽  
Ryan J. Foley ◽  
Armin Rest ◽  
...  
Keyword(s):  
High Velocity ◽  
High Redshift ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Significant Difference ◽  
Type Ia ◽  
Show Evidence ◽  
Ia Supernovae

Abstract The ejecta velocities of Type Ia supernovae (SNe Ia), as measured by the Si ii λ6355 line, have been shown to correlate with other supernova properties, including color and standardized luminosity. We investigate these results using the Foundation Supernova Survey, with a spectroscopic data release presented here, and photometry analyzed with the SALT2 light-curve fitter. We find that the Foundation data do not show significant evidence for an offset in color between SNe Ia with high and normal photospheric velocities, with Δc = 0.004 ± 0.015. Our SALT2 analysis does show evidence for redder high-velocity SNe Ia in other samples, including objects from the Carnegie Supernova Project, with a combined sample yielding Δc = 0.018 ± 0.008. When split on velocity, the Foundation SNe Ia also do not show a significant difference in Hubble diagram residual, ΔHR = 0.015 ± 0.049 mag. Intriguingly, we find that SN Ia ejecta velocity information may be gleaned from photometry, particularly in redder optical bands. For high-redshift SNe Ia, these rest-frame red wavelengths will be observed by the Nancy Grace Roman Space Telescope. Our results are in line with previous work that suggests SN Ia host-galaxy stellar mass is correlated with ejecta velocity: high-velocity SNe Ia are found nearly exclusively in high-stellar-mass hosts. However, host-galaxy properties alone do not explain velocity-dependent differences in supernova colors and luminosities across samples. Measuring and understanding the connection between intrinsic explosion properties and supernova environments, across cosmic time, will be important for precision cosmology with SNe Ia.

scholarly journals Understanding type Ia supernovae through their U-band spectra

2018 ◽  
Vol 614 ◽  
pp. A71 ◽  
Author(s):  
J. Nordin ◽  
G. Aldering ◽  
P. Antilogus ◽  
C. Aragon ◽  
S. Bailey ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
High Redshift ◽  
Host Galaxy ◽  
Band Spectrum ◽  
Type Ia Supernovae ◽  
Explosion Process ◽  
Type Ia ◽  
The Difference ◽  
Band Spectra ◽  
Ia Supernovae

Context. Observations of type Ia supernovae (SNe Ia) can be used to derive accurate cosmological distances through empirical standardization techniques. Despite this success neither the progenitors of SNe Ia nor the explosion process are fully understood. The U-band region has been less well observed for nearby SNe, due to technical challenges, but is the most readily accessible band for high-redshift SNe. Aims. Using spectrophotometry from the Nearby Supernova Factory, we study the origin and extent of U-band spectroscopic variations in SNe Ia and explore consequences for their standardization and the potential for providing new insights into the explosion process. Methods. We divide the U-band spectrum into four wavelength regions λ(uNi), λ(uTi), λ(uSi) and λ(uCa). Two of these span the Ca H&K λλ 3934, 3969 complex. We employ spectral synthesis using SYNAPPS to associate the two bluer regions with Ni/Co and Ti. Results. The flux of the uTi feature is an extremely sensitive temperature/luminosity indicator, standardizing the SN peak luminosity to 0.116 ± 0.011 mag root mean square (RMS). A traditional SALT2.4 fit on the same sample yields a 0.135 mag RMS. Standardization using uTi also reduces the difference in corrected magnitude between SNe originating from different host galaxy environments. Early U-band spectra can be used to probe the Ni+Co distribution in the ejecta, thus offering a rare window into the source of light curve power. The uCa flux further improves standardization, yielding a 0.086 ± 0.010 mag RMS without the need to include an additional intrinsic dispersion to reach χ2∕dof ~ 1. This reduction in RMS is partially driven by an improved standardization of Shallow Silicon and 91T-like SNe.

scholarly journals See Change: VLT spectroscopy of a sample of high-redshift Type Ia supernova host galaxies

2020 ◽  
Vol 495 (4) ◽  
pp. 3859-3880 ◽  
Author(s):  
S C Williams ◽  
I M Hook ◽  
B Hayden ◽  
J Nordin ◽  
G Aldering ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Light Curves ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Very Large Telescope ◽  
Type Ia ◽  
Ia Supernovae

ABSTRACT The Supernova Cosmology Project has conducted the ‘See Change’ programme, aimed at discovering and observing high-redshift (1.13 ≤ z ≤ 1.75) Type Ia supernovae (SNe Ia). We used multifilter Hubble Space Telescope (HST) observations of massive galaxy clusters with sufficient cadence to make the observed SN Ia light curves suitable for a cosmological probe of dark energy at z > 0.5. This See Change sample of SNe Ia with multi-colour light curves will be the largest to date at these redshifts. As part of the See Change programme, we obtained ground-based spectroscopy of each discovered transient and/or its host galaxy. Here, we present Very Large Telescope (VLT) spectra of See Change transient host galaxies, deriving their redshifts, and host parameters such as stellar mass and star formation rate. Of the 39 See Change transients/hosts that were observed with the VLT, we successfully determined the redshift for 26, including 15 SNe Ia at z > 0.97. We show that even in passive environments, it is possible to recover secure redshifts for the majority of SN hosts out to z = 1.5. We find that with typical exposure times of 3−4 h on an 8-m-class telescope we can recover ∼75 per cent of SN Ia redshifts in the range of 0.97 < z < 1.5. Furthermore, we show that the combination of HST photometry and VLT spectroscopy is able to provide estimates of host galaxy stellar mass that are sufficiently accurate for use in a mass-step correction in the cosmological analysis.

scholarly journals First cosmology results using type Ia supernovae from the Dark Energy Survey: the effect of host galaxy properties on supernova luminosity

2020 ◽  
Vol 494 (3) ◽  
pp. 4426-4447 ◽  
Author(s):  
M Smith ◽  
M Sullivan ◽  
P Wiseman ◽  
R Kessler ◽  
D Scolnic ◽  
...  
Keyword(s):  
Dark Energy ◽  
Bias Correction ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Photometric Measurements ◽  
Ia Supernovae ◽  
Energy Survey

ABSTRACT We present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type Ia supernovae discovered by the Dark Energy Survey Supernova Program (DES-SN) and used in the first DES-SN cosmological analysis. For the DES-SN sample, when considering a 5D (z, x1, c, α, β) bias correction, we find evidence of a Hubble residual ‘mass step’, where SNe Ia in high-mass galaxies (>1010M⊙) are intrinsically more luminous (after correction) than their low-mass counterparts by $\gamma =0.040\pm 0.019$ mag. This value is larger by 0.031 mag than the value found in the first DES-SN cosmological analysis. This difference is due to a combination of updated photometric measurements and improved star formation histories and is not from host-galaxy misidentification. When using a 1D (redshift-only) bias correction the inferred mass step is larger, with $\gamma =0.066\pm 0.020$ mag. The 1D−5D γ difference for DES-SN is $0.026\pm 0.009$ mag. We show that this difference is due to a strong correlation between host galaxy stellar mass and the x1 component of the 5D distance-bias correction. Including an intrinsic correlation between the observed properties of SNe Ia, stretch and colour, and stellar mass in simulated SN Ia samples, we show that a 5D fit recovers γ with −9 mmag bias compared to a +2 mmag bias for a 1D fit. This difference can explain part of the discrepancy seen in the data. Improvements in modelling correlations between galaxy properties and SN is necessary to ensure unbiased precision estimates of the dark energy equation of state as we enter the era of LSST.

scholarly journals An Efficient Approach to Obtaining Large Numbers of Distant Supernova Host Galaxy Redshifts

2013 ◽  
Vol 30 ◽  
Author(s):  
C. Lidman ◽  
V. Ruhlmann-Kleider ◽  
M. Sullivan ◽  
J. Myzska ◽  
P. Dobbie ◽  
...  
Keyword(s):  
High Redshift ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Wide Field ◽  
Host Galaxies ◽  
Dark Energy Survey ◽  
Large Numbers ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

AbstractWe use the wide-field capabilities of the 2 degree field fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first 3 years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ks per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our sample that hosted photometrically classified Type Ia supernovae (SNe Ia) is z ~ 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the 3-year sample of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4-m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of the sky that will be covered by future high-redshift supernova surveys, such as the Dark Energy Survey.

scholarly journals The Effect of Environment on Type Ia Supernovae in the Dark Energy Survey Three-Year Cosmological Sample

2020 ◽  
Author(s):  
L Kelsey ◽  
M Sullivan ◽  
M Smith ◽  
P Wiseman ◽  
D Brout ◽  
...  
Keyword(s):  
Dark Energy ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Sample Median ◽  
Star Forming ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

Abstract Analyses of type Ia supernovae (SNe Ia) have found puzzling correlations between their standardised luminosities and host galaxy properties: SNe Ia in high-mass, passive hosts appear brighter than those in lower-mass, star-forming hosts. We examine the host galaxies of SNe Ia in the Dark Energy Survey three-year spectroscopically-confirmed cosmological sample, obtaining photometry in a series of ‘local’ apertures centred on the SN, and for the global host galaxy. We study the differences in these host galaxy properties, such as stellar mass and rest-frame U − R colours, and their correlations with SN Ia parameters including Hubble residuals. We find all Hubble residual steps to be >3σ in significance, both for splitting at the traditional environmental property sample median and for the step of maximum significance. For stellar mass, we find a maximal local step of 0.098 ± 0.018 mag; ∼0.03 mag greater than the largest global stellar mass step in our sample (0.070 ± 0.017 mag). When splitting at the sample median, differences between local and global U − R steps are small, both ∼0.08 mag, but are more significant than the global stellar mass step (0.057 ± 0.017 mag). We split the data into sub-samples based on SN Ia light curve parameters: stretch (x1) and colour (c), finding that redder objects (c > 0) have larger Hubble residual steps, for both stellar mass and U − R, for both local and global measurements, of ∼0.14 mag. Additionally, the bluer (star-forming) local environments host a more homogeneous SN Ia sample, with local U − R r.m.s. scatter as low as 0.084 ± 0.017 mag for blue (c < 0) SNe Ia in locally blue U − R environments.

scholarly journals The Host Galaxies of High-Redshift Type Ia Supernovae

2005 ◽  
Vol 192 ◽  
pp. 555-560
Author(s):  
Mark Sullivan ◽  
Richard Ellis ◽  
Keyword(s):  
Cosmological Constant ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Type Systems ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Early Type ◽  
Late Type ◽  
Type Ia ◽  
Ia Supernovae

SummaryWe present new results on the Hubble diagram of distant type Ia supernovae (SNe Ia) segregated according to the type of host galaxy. This makes it possible to check earlier evidence for a cosmological constant by explicitly comparing SNe residing in galaxies likely to contain negligible dust with the larger sample. The cosmological parameters derived from these SNe Ia hosted by presumed dust-free early-type galaxies support earlier claims for a cosmological constant, which we demonstrate at ≃ 5σ significance, and the internal extinction implied is small even for late-type systems (AB < 0.2). Furthermore, the scatter observed in the SNe Ia Hubble diagrams correlates closely with host galaxy morphology. We find this scatter is smallest for SNe Ia occurring in early-type hosts and largest for those in late-type galaxies. Moreover, SNe residing in late-type hosts appear fainter in their light-curve-width-corrected luminosity than those in early-type hosts, as expected if a modest amount of dust extinction is a contributing factor. Thus, our data demonstrate that host galaxy extinction is unlikely to systematically dim distant SNe Ia in a manner that would produce a spurious cosmological constant.

scholarly journals Spectra of High-Redshift Type Ia Supernovae and a Comparison with Their Low-Redshift Counterparts

2005 ◽  
Vol 130 (6) ◽  
pp. 2788-2803 ◽  
Author(s):  
I. M. Hook ◽  
D. A. Howell ◽  
G. Aldering ◽  
R. Amanullah ◽  
M. S. Burns ◽  
...  
Keyword(s):  
High Redshift ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae

scholarly journals Model-independent cosmic acceleration and redshift-dependent intrinsic luminosity in type-Ia supernovae

2019 ◽  
Vol 625 ◽  
pp. A15 ◽  
Author(s):  
I. Tutusaus ◽  
B. Lamine ◽  
A. Blanchard
Keyword(s):  
Spline Interpolation ◽  
High Redshift ◽  
Cosmic Acceleration ◽  
Expansion Rate ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Model Independent ◽  
Ia Supernovae ◽  
The Universe ◽  
Intrinsic Luminosity

Context. The cosmological concordance model (ΛCDM) is the current standard model in cosmology thanks to its ability to reproduce the observations. The first observational evidence for this model appeared roughly 20 years ago from the type-Ia supernovae (SNIa) Hubble diagram from two different groups. However, there has been some debate in the literature concerning the statistical treatment of SNIa, and their stature as proof of cosmic acceleration. Aims. In this paper we relax the standard assumption that SNIa intrinsic luminosity is independent of redshift, and examine whether it may have an impact on our cosmological knowledge and more precisely on the accelerated nature of the expansion of the universe. Methods. To maximise the scope of this study, we do not specify a given cosmological model, but we reconstruct the expansion rate of the universe through a cubic spline interpolation fitting the observations of the different cosmological probes: SNIa, baryon acoustic oscillations (BAO), and the high-redshift information from the cosmic microwave background (CMB). Results. We show that when SNIa intrinsic luminosity is not allowed to vary as a function of redshift, cosmic acceleration is definitely proven in a model-independent approach. However, allowing for redshift dependence, a nonaccelerated reconstruction of the expansion rate is able to fit, at the same level of ΛCDM, the combination of SNIa and BAO data, both treating the BAO standard ruler rd as a free parameter (not entering on the physics governing the BAO), and adding the recently published prior from CMB observations. We further extend the analysis by including the CMB data. In this case we also consider a third way to combine the different probes by explicitly computing rd from the physics of the early universe, and we show that a nonaccelerated reconstruction is able to nicely fit this combination of low- and high-redshift data. We also check that this reconstruction is compatible with the latest measurements of the growth rate of matter perturbations. We finally show that the value of the Hubble constant (H0) predicted by this reconstruction is in tension with model-independent measurements. Conclusions. We present a model-independent reconstruction of a nonaccelerated expansion rate of the universe that is able to fit all the main background cosmological probes nicely. However, the predicted value of H0 is in tension with recent direct measurements. Our analysis points out that a final reliable and consensual value for H0 is critical to definitively prove cosmic acceleration in a model-independent way.

scholarly journals Exploring the shell model of high-velocity features of Type Ia supernovae using tardis

2019 ◽  
Vol 484 (4) ◽  
pp. 4785-4800 ◽  
Author(s):  
Brian W Mulligan ◽  
Kaicheng Zhang ◽  
J Craig Wheeler
Keyword(s):  
Shell Model ◽  
High Velocity ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae
Sign in / Sign up

Export Citation Format

Share Document