Type Ia Supernova Luminosity Research Articles

Unveiling the Hubble constant through galaxy cluster gas mass fractions

In this work, we obtain Hubble constant (H0) estimates by using two galaxy cluster gas mass fraction measurement samples, Type Ia supernovae luminosity distances, and the validity of the cosmic distance duality relation. Notably, the angular diameter distance (ADD) to each galaxy cluster in the samples is determined by combining its gas mass fraction measurement with galaxy clustering observations, more precisely, the Ωb/Ωm ratio. Such a combination results in a H0 estimate that is independent of a specific cosmological framework. In one of the samples, the gas fraction measurements were calculated in spherical shells at radii near r2500 (44 data points), while in the other (103 data points) the measurements were calculated within r500. We find H0=72.7−5.6+6.3 km/s/Mpc at 68% CL for the joint analysis of these data sets. We also investigate the impact on the H0 determination by exploring the precision and number of gas mass fraction data by performing a data Monte Carlo simulation. Our simulations show that future measurements could achieve a precision of up to 5% for H0.

[O ii] as an effective indicator of the dependence between the standardized luminosities of Type Ia supernovae and the properties of their host galaxies

[O <scp>ii</scp>] as an effective indicator of the dependence between the standardized luminosities of Type Ia supernovae and the properties of their host galaxies

Tracing back the birth environments of Type Ia supernova progenitor stars: a pilot study based on 44 early-type host galaxies

ABSTRACT The environmental dependence of Type Ia supernova (SN Ia) luminosities is well established, and efforts are being made to find its origin. Previous studies typically use the currently observed status of the host galaxy. However, given the delay time between the birth of the progenitor star and the SN Ia explosion, the currently observed status may differ from the birth environment of the SN Ia progenitor star. In this paper, employing the chemical evolution and accurately determined stellar population properties of 44 early-type host galaxies, we, for the first time, estimate the SN Ia progenitor star birth environment, specifically [Fe/H]Birth and [α/Fe]Birth. We show that [α/Fe]Birth has a $30.4^{\text{+10.6}}_{-10.1}{{\ \rm per\ cent}}$ wider range than the currently observed [α/Fe]Current, while the range of [Fe/H]Birth is not statistically different ($17.9^{\text{+26.0}}_{-27.1}{{\ \rm per\ cent}}$) to that of [Fe/H]Current. The birth and current environments of [Fe/H] and [α/Fe] are sampled from different populations (p-values of the Kolmogorov–Smirnov test &amp;lt;0.01). We find that light-curve fit parameters are insensitive to [Fe/H]Birth (&amp;lt;0.9σ for the non-zero slope), while a linear trend is observed with Hubble residuals (HRs) at the 2.4σ significance level. With [α/Fe]Birth, no linear trends (&amp;lt;1.1σ) are observed. Interestingly, we find that [α/Fe]Birth clearly splits the SN Ia sample into two groups: SN Ia exploded in [α/Fe]Birth-rich or [α/Fe]Birth-poor environments. SNe Ia exploded in different [α/Fe]Birth groups have different weighted-means of light-curve shape parameters: 0.81 ± 0.33 (2.5σ). They are thought to be drawn from different populations (p-value = 0.01). Regarding SN Ia colour and HRs, there is no difference (&amp;lt;1.0σ) in the weighted-means and distribution (p-value &amp;gt; 0.27) of each [α/Fe]Birth group.

Progenitor-age dependence of type Ia supernova luminosity and its cosmological implication

Progenitor-age dependence of type Ia supernova luminosity and its cosmological implication

Examining the validity of the minimal varying speed of light model through cosmological observations: Relaxing the null curvature constraint

We revisit a consistency test for the speed of light variability, using the latest cosmological observations. This exercise can serve as a new diagnostics for the standard cosmological model and distinguish between the minimal varying speed of light in the Friedmann-Lemaître-Robertson-Walker universe. We deploy Gaussian processes to reconstruct cosmic distances and ages in the redshift range 0<z<2 utilizing the Pantheon compilation of type-Ia supernova luminosity distances (SN), cosmic chronometers from differential galaxy ages (CC), and measurements of both radial and transverse modes of baryon acoustic oscillations (r-BAO and a-BAO) respectively. Such a test has the advantage of being independent of any non-zero cosmic curvature assumption – which can be degenerated with some variable speed of light models – as well as any dark energy model. We also examine the impact of cosmological priors on our analysis, such as the Hubble constant, supernova absolute magnitude, and the sound horizon scale. We find null evidence for the speed of light variability hypothesis for most choices of priors and data-set combinations. However, mild deviations are seen at ∼2σ confidence level for redshifts z<1 with some specific prior choices when r-BAO data is employed, and at z>1 with a particular reconstruction kernel when a-BAO data are included. Still, we ascribe no statistical significance to this result bearing in mind the degeneracy between the associated priors for combined analysis, and incompleteness of the a-BAO data set at higher z.

Reconsidering photometric estimation of local star formation environment and its correlation with Type Ia supernova luminosity

ABSTRACT Recent studies on the environmental dependence of Type Ia supernova (SN Ia) luminosity focus on the local environment where the SN exploded, considering that this is more directly linked to the SN progenitors. However, there is a debate about the local environmental, specifically local star formation rate (SFR), dependence of the SN Ia luminosity. A recent study claims that the dependence is insignificant (0.051 ± 0.020 mag; 2.6σ), based on the local SFR measurement by fitting local ugrizy photometry data. However, we find that this photometric local SFR measurement is inaccurate. We argue this based on the theoretical background of SFR measurement and the methodology used to make that claim with their local ugrizy photometry data, especially due to a limited range of extinction parameters used when fitting the data. Therefore, we reanalyse the same host galaxies with the same fitting code, but with more physically motivated extinction treatments and global ugriz photometry of host galaxies. We estimate global stellar mass and SFR. Then, local star formation environments are inferred by using the method which showed that SNe Ia in globally passive galaxies have locally passive environments, while those in globally star-forming low-mass galaxies have locally star-forming environments. We find that there is significant local environmental dependence of SN Ia luminosities: SNe Ia in locally star-forming environments are 0.072 ± 0.021 mag (3.4σ) fainter than those in locally passive environments, even though SN Ia luminosities have been further corrected by the BEAMS with Bias Corrections method that reduces the size of the dependence.

Leveraging SN Ia spectroscopic similarity to improve the measurement of H 0

Recent studies suggest spectroscopic differences explain a fraction of the variation in Type Ia supernova (SN Ia) luminosities after light-curve/color standardization. In this work, (i) we empirically characterize the variations of standardized SN Ia luminosities, and (ii) we use a spectroscopically inferred parameter, SIP, to improve the precision of SNe Ia along the distance ladder and the determination of the Hubble constant (H 0). First, we show that the Pantheon+ covariance model modestly overestimates the uncertainty of standardized magnitudes by ∼ 7%, in the parameter space used by the SH0ES Team to measure H 0; accounting for this alone yields H 0 = 73.01 ± 0.92 km s-1 Mpc-1. Furthermore, accounting for spectroscopic similarity between SNe Ia on the distance ladder reduces their relative scatter to ∼ 0.12 mag per object (compared to ∼ 0.14 mag previously). Combining these two findings in the model of SN covariance, we find an overall 14% reduction (to ± 0.85 km s-1 Mpc-1) of the uncertainty in the Hubble constant and a modest increase in its value. Including a budget for systematic uncertainties itemized by Riess et al. (2022a), we report an updated local Hubble constant with ∼ 1.2% uncertainty, H 0 = 73.29 ± 0.90 km s-1 Mpc-1. We conclude that spectroscopic differences among photometrically standardized SNe Ia do not explain the “Hubble tension”. Rather, accounting for such differences increases its significance, as the discrepancy against ΛCDM calibrated by the Planck 2018 measurement rises to 5.7σ.

Carbon Stars as Standard Candles: An Empirical Test for the Reddening, Metallicity, and Age Sensitivity of the J-region Asymptotic Giant Branch (JAGB) Method

The J-region Asymptotic Giant Branch (JAGB) method is a standard candle based on the intrinsic luminosities of carbon stars in the near-infrared. We directly constrain the impact of metallicity, age, and reddening on the JAGB method. We assess how the mode, skew, and spread of the JAGB star LF change throughout diverse stellar environments in M31's NE disk from 13 < d < 18 kpc using data from the Panchromatic Hubble Andromeda Treasury (PHAT). As expected, the mode is found to be fainter in higher-reddening regions. To cross-check this result, we also measure a fiducial J-band ground-based JAGB distance using data from the UKIRT/WFCam in M31's outermost disk (18 < d < 40 kpc) where internal reddening is minimal. We find that this J-band distance modulus agrees well with the F110W distance moduli measured in the lowest-reddening regions of the PHAT data, demonstrating the JAGB method is most accurate if measured in the low-reddening outer disks of galaxies. On the other hand, the mode of the JAGB star LF appears empirically to show no dependence on age or metallicity within the range −0.18 < [M/H] < −0.26 dex. In conclusion, the JAGB method proves to be a robust standard candle capable of calibrating the luminosities of Type Ia supernovae and therefore providing a high-accuracy, high-precision measurement of the Hubble constant.

Detection Possibility of Continuous Gravitational Waves from Rotating Magnetized Neutron Stars

In recent decades, several neutron stars (NSs), particularly pulsars, with masses of M > 2 M ⊙ have been observed. On the other hand, the existence of massive white dwarfs, even violating the Chandrasekhar mass limit, was inferred from the peak luminosities of Type Ia supernovae. Hence, there is a generic question of the origin of massive compact objects. Here we explore the existence of massive, magnetized, rotating NSs with the soft and steep equations of state by solving axisymmetric stationary stellar equilibria in general relativity. For our purposes, we consider the Einstein equation solver for stellar structure XNS code. Such rotating NSs with magnetic fields and rotation axes misaligned, and hence a nonzero obliquity angle, can emit continuous gravitational waves (GWs), which can be detected by upcoming detectors, e.g., the Einstein Telescope, etc. We discuss the decay of the magnetic field, angular velocity, and obliquity angle with time due to angular momentum extraction by GWs and dipole radiation, which determine the timescales related to the GW emission. Further, in the Alfvén timescale, a differentially rotating, massive proto-NS rapidly settles into a uniformly rotating, less massive NS due to magnetic braking and viscosity. These explorations suggest that detecting massive NSs is challenging and sets a timescale for detection. We calculate the signal-to-noise ratio of GW emission, which confirms that any detector cannot detect them immediately, but that they are detectable by the Einstein Telescope and Cosmic Explorer over months of integration time, leading to direct detection of NSs.

Further evidence that galaxy age drives observed Type Ia supernova luminosity differences

ABSTRACT Type Ia supernovae (SNe Ia) are explosions of white dwarf stars that facilitate exquisite measurements of cosmological expansion history, but improvements in accuracy and precision are hindered by observational biases. Of particular concern is the apparent difference in the corrected brightnesses of SNe Ia in different host galaxy environments. SNe Ia in more massive, passive, older environments appear brighter after having been standardized by their light-curve properties. The luminosity difference commonly takes the form of a step function. Recent works imply that environmental characteristics that trace the age of the stellar population in the vicinity of SNe show the largest steps. Here, we use simulations of SN Ia populations to test the impact of using different tracers and investigate promising new models of the step. We test models with a total-to-selective dust extinction ratio RV that changes between young and old SN Ia host galaxies, as well as an intrinsic luminosity difference between SNe from young and old progenitors. The data are well replicated by a model driven by a galaxy-age varying RV and no intrinsic SN luminosity difference, and we find that specific star formation rate measured locally to the SN is a relatively pure tracer of this galaxy-age difference. We cannot rule out an intrinsic difference causing part of the observed step and show that if luminosity differences are caused by multiple drivers then no single environmental measurement is able to accurately trace them. We encourage the use of multiple tracers in luminosity corrections to negate this issue.

Gravitational orbits in the expanding Universe revisited

Modified Newtonian equations for gravitational orbits in the expanding Universe indicate that local gravitationally bounded systems like galaxies and planetary systems are unaffected by the expansion of the Universe. This result is derived for the space expansion described by the standard FLRW metric. In this paper, the modified Newtonian equations are derived for the space expansion described by the conformal cosmology (CC) metric. In this metric, the comoving and proper times are different similarly as the comoving and proper distances. As shown by Vavryčuk (Front. Phys. 2022), this metric is advantageous, because it properly predicts the cosmic time dilation, and fits the Type Ia supernova luminosity observations with no need to introduce dark energy. Surprisingly, the solution of the equations for gravitational orbits based on the CC metric behaves quite differently than that based on the FLRW metric. In contrast to the common opinion that local systems resist the space expansion, they expand according to the Hubble flow in the CC metric. The evolution of the local systems with cosmic time is exemplified on numerical modelling of spiral galaxies. The size of the spiral galaxies grows consistently with observations and a typical spiral pattern is well reproduced. The theory predicts flat rotation curves without an assumption of dark matter surrounding the galaxy. The theory resolves challenges to the ΛCDM model such as the problem of faint satellite galaxies, baryonic Tully-Fisher relation or the radial acceleration relation. Furthermore, puzzles in the solar system are successfully explained such as the Faint young Sun paradox or the Moon’s and Titan’s orbit anomalies.

The impact of weak lensing on Type Ia supernovae luminosity distances

ABSTRACT When Type Ia supernovae are used to infer cosmological parameters, their luminosities are compared to those from a homogeneous cosmology. In this note, we propose a test to examine to what degree SN Ia have been observed on lines of sight where the average matter density is not representative of the homogeneous background. We apply our test to the Pantheon SN Ia compilation, and find two redshift bins which indicate a moderate bias to over-density at ∼2σ. We modify the Tripp estimator to explicitly de-lens SN Ia magnitudes, and show that this reduces scatter of Hubble diagram residuals. Using our revised Tripp estimator, the effect on cosmological parameters from Pantheon in ΛCDM is however small with a change in mean value from Ωm = 0.317 ± 0.027 (baseline) to Ωm = 0.312 ± 0.025 (de-lensed). For the Flat wCDM case, it is Ωm = 0.332 ± 0.049 and w = −1.16 ± 0.16 (baseline) versus Ωm = 0.316 ± 0.048 and w = −1.12 ± 0.15 (de-lensed). We note that the effect of lensing on cosmological parameters may be larger for future high-z surveys.

Evidence for strong progenitor age dependence of type Ia supernova luminosity standardization process

ABSTRACT Supernova (SN) cosmology is based on the assumption that the width–luminosity relation (WLR) and the colour–luminosity relation (CLR) in the type Ia SN luminosity standardization would not show absolute magnitude differences with progenitor age. Unlike this expectation, recent age datings of stellar populations in host galaxies have shown significant correlations between progenitor age and Hubble residual (HR). Here, we show that this correlation originates from a strong progenitor age dependence of the zero-points of the WLR and the CLR, in the sense that SNe from younger progenitors are fainter each at given light-curve parameters x1 and c. This 4.6σ result is reminiscent of Baade’s discovery of the zero-point variation of the Cepheid period–luminosity relation with age, and, as such, causes a serious systematic bias with redshift in SN cosmology. Other host properties show substantially smaller and insignificant offsets in the WLR and CLR for the same data set. We illustrate that the differences between the high-$z$ and low-$z$ SNe in the WLR and CLR, and in HR after the standardization, are fully comparable to those between the correspondingly young and old SNe at intermediate redshift, indicating that the observed dimming of SNe with redshift may well be an artefact of overcorrection in the luminosity standardization. When this systematic bias with redshift is properly taken into account, there is little evidence left for an accelerating universe, in discordance with other probes, urging the follow-up investigations with larger samples at different redshift bins.

A galaxy-driven model of type Ia supernova luminosity variations

ABSTRACT Type Ia supernovae (SNe Ia) are used as standardizable candles to measure cosmological distances, but differences remain in their corrected luminosities which display a magnitude step as a function of host galaxy properties such as stellar mass and rest-frame U−R colour. Identifying the cause of these steps is key to cosmological analyses and provides insight into SN physics. Here we investigate the effects of SN progenitor ages on their light-curve properties using a galaxy-based forward model that we compare to the Dark Energy Survey 5-yr SN Ia sample. We trace SN Ia progenitors through time and draw their light-curve width parameters from a bimodal distribution according to their age. We find that an intrinsic luminosity difference between SNe of different ages cannot explain the observed trend between step size and SN colour. The data split by stellar mass are better reproduced by following recent work implementing a step in total-to-selective dust extinction ratio (RV) between low- and high-mass hosts, although an additional intrinsic luminosity step is still required to explain the data split by host galaxy U−R. Modelling the RV step as a function of galaxy age provides a better match overall. Additional age versus luminosity steps marginally improve the match to the data, although most of the step is absorbed by the width versus luminosity coefficient α. Furthermore, we find no evidence that α varies with SN age.

Effect of evolving physical constants on type Ia supernova luminosity

ABSTRACT Type Ia supernovae, SNeIa, are used as standard candles in cosmology to determine the distances of the galaxies harbouring them. We show that the luminosity of an SNIa depends on its distance from us when physical constants (the speed of light c, the gravitational constant G, and the Planck constant h) are permitted to evolve. It is because the Chandrasekhar mass of the white dwarf that explodes to create SNIa depends on the values of the constants at the epoch the SNIa is formed. We show that the SNeIa luminosities could be about four times higher in the past than they are now. Thus, the luminosity distance estimation of the earliest SNeIa could be off by up to a factor of 2. Cosmological parameters, determined with this correction applied to the redshift versus distance modulus data base (Pantheon SNeIa), are not very different from those from the standard ΛCDM model without this correction, except for the dark-energy density and the curvature energy density; the latter increases at the cost of the former. Variations of the constants are given by $\dot{G}/G = \ 3.90 \ ( { \pm 0.04} ) \times {10^{ - 10}}\ {\rm y{r^{ - 1}}}$and $\dot{c}/c = \dot{h}/h\ = \ 1.30\ ( { \pm 0.01} ) \times {10^{ - 10}}\ {\rm y{r^{ - 1}}}$ at present. These variations are valid only when $G,\ c,\ $and$\ h$ are permitted to vary concurrently rather than individually.

A non-parametric test of variability of Type Ia supernovae luminosity and CDDR

The first observational evidence for cosmic acceleration appeared from Type Ia supernovae (SNe Type Ia) Hubble diagram from two different groups. However, the empirical treatment of SNe Type Ia and their ability to show cosmic acceleration have been the subject of some debate in the literature. In this work we probe the assumption of redshift-independent absolute magnitude (MB) of SNe along with its correlation with spatial curvature (Ωk0) and cosmic distance duality relation (CDDR) parameter (η(z)). This work is divided into two parts. Firstly, we check the validity of CDDR which relates the luminosity distance (dL) and angular diameter distance (dA) via redshift. We use the Pantheon SNe Ia dataset combined with the H(z) measurements derived from the cosmic chronometers. Further, four different redshift-dependent parametrizations of the distance duality parameter (η(z)) are used. The CDDR is fairly consistent for almost every parametrization within a 2σ confidence level in both flat and a non-flat universe. In the second part, we assume the validity of CDDR and emphasize on the variability of M_B and its correlation with Ωk0. We choose four different redshift-dependent parametrizations of MB. The results indicate no evolution of MB within 2σ confidence level. For all parametrizations, the best fit value of Ωk0 indicates a flat universe at 2σ confidence level. However a mild inclination towards a non flat universe is also observed. We have also examined the dependence of the results on the choice of different priors for H0.

The ZTF-BTS Type Ia supernovae luminosity function is consistent with a single progenitor channel for the explosions

ABSTRACT We construct the Type Ia supernovae (SNe Ia) luminosity function (LF) using the Zwicky Transient Facility Bright Transient Survey (BTS) catalogue. While this magnitude-limited survey has an unprecedented number of objects, it suffers from large distance uncertainties and lacks an estimation of host extinction. We bypass these issues by calculating the intrinsic luminosities from the shape parameters of the light curve’s g and r bands, with the luminosities calibrated from the well observed SNe Ia sample of the Carnegie Supernova Project, allowing us to construct, for the first time, the intrinsic LF of SNe Ia. We then use a novel tight relation between the colour stretch and the synthesized 56Ni mass, MNi56, to determine the MNi56 distribution of SNe Ia. We find that the LFs are unimodal, with their peaks in line with previous results, but have a much lower rate of dim events and luminous events. We show that the features on top of the unimodal LF-derived distributions are all compatible with statistical noise, consistent with a single progenitor channel for the explosions. We further derive, for the first time, the SNe Ia distribution of host galaxy extinction, and find a mean selective extinction of E(B − V) ≈ 0.1 and a non-negligible fraction with large, $\gt 1\, \text{mag}$, extinction in the optical bands. The high extinction is typical for luminous SNe, supporting their young population origin.

Rapid transition of Geff at zt≃0.01 as a possible solution of the Hubble and growth tensions

The mismatch in the value of the Hubble constant from low- and high-redshift observations may be recast as a discrepancy between the low- and high-redshift determinations of the luminosity of Type Ia supernovae, the latter featuring an absolute magnitude which is $\approx 0.2$~mag lower. Here, we propose that a rapid transition in the value of the relative effective gravitational constant $\mu_G\equiv\frac{G_{\rm eff}}{G_N}$ at $z_t\simeq 0.01$ could explain the lower luminosity (higher magnitude) of local supernovae, thus solving the $H_0$ crisis. A model that features $\mu_G = 1$ for $z \lesssim 0.01$ but $\mu_G \simeq 0.9$ for $z \gtrsim 0.01$ is trivially consistent with local gravitational constraints but would raise the Chandrasekhar mass and so decrease the absolute magnitude of Type Ia supernovae at $z \gtrsim 0.01$ by the required value of $\approx 0.2$~mag. Such a rapid transition of the effective gravitational constant would not only resolve the Hubble tension but it would also help resolve the growth tension as it would reduce the growth of density perturbations without affecting the Planck/$\Lambda$CDM background expansion.

On the relationship between Type Ia supernova luminosity and host-galaxy properties

ABSTRACT A string of recent studies has debated the exact form and physical origin of an evolutionary trend between the peak luminosity of Type Ia supernovae (SNe Ia) and the properties of the galaxies that host them. We shed new light on the discussion by presenting an analysis of ∼200 low-redshift SNe Ia in which we measure the separation of Hubble residuals (HR; as probes of luminosity) between two host-galaxy morphological types. We show that this separation can test the predictions made by recently proposed models, using an independently and empirically determined distribution of each morphological type in host-property space. Our results are partially consistent with the new HR–age slope, but we find significant scatter in the predictions from different galaxy catalogues. The inconsistency in age illuminates an issue in the current debate that was not obvious in the long-discussed mass models: HR–host-property models are strongly dependent on the methods employed to determine galaxy properties. While our results demonstrate the difficulty in constructing a universal model for age as a proxy for host environment, our results indeed identify evolutionary trends between mass, age, morphology, and HR values, encouraging (or requiring, if such trends are to be accounted for in cosmological studies) further investigation.

Gravitational Wave in f(R) Gravity: Possible Signature of Sub- and Super-Chandrasekhar Limiting-mass White Dwarfs

Abstract After the prediction of many sub- and super-Chandrasekhar (at least a dozen for the latter) limiting-mass white dwarfs (WDs), hence apparently a peculiar class of WDs, from the observations of luminosity of Type Ia supernovae, researchers have proposed various models to explain these two classes of WD separately. We earlier showed that these two peculiar classes of WD, along with the regular WD, can be explained by a single form of the f(R) gravity, whose effect is significant only in the high-density regime, and it almost vanishes in the low-density regime. However, since there is no direct detection of such a WD, it is difficult to single out one specific theory from the zoo of modified theories of gravity. We discuss the possibility of direct detection of such a WD in gravitational wave (GW) astronomy. It is well known that in f(R) gravity more than two polarization modes are present. We estimate the amplitudes of all the relevant modes for the peculiar and the regular WD. We further discuss the possibility of their detections through future-based GW detectors, such as LISA, ALIA, DECIGO, BBO, or the Einstein Telescope, and thereby put constraints on or rule out various modified theories of gravity. This exploration links the theory with possible observations through GW in f(R) gravity.