Peak Luminosity Relation Research Articles

A Systematic Study on the Rise Time–Peak Luminosity Relation for Bright Optical Transients Powered by Wind Shock Breakout

Abstract A number of astrophysical transients originating from stellar explosions are powered by the collision of the ejected material with the circumstellar medium, which efficiently produces thermal radiation via shock dissipation. We investigate how such interaction-powered transients are distributed in the peak bolometric luminosity versus the rise time phase space. Taking advantage of less time-consuming one-dimensional simulations with spherical symmetry, we calculated more than 500 models with different circumstellar mass and radius, ejecta mass and energy, and chemical compositions. The peak bolometric luminosity, the total radiated energy, and the rise time of the interaction-powered emission are measured for each simulated light curve. We consider how these characteristic quantities are determined as a function of the model parameters and discuss possible implications for the observed populations of (potential) interaction-powered transients, such as Type IIn supernovae and fast blue optical transients.

Constraints on w0 and wa of dark energy from high-redshift gamma-ray bursts

Abstract We extend the Hubble diagram up to z= 5.6 using 63 gamma-ray bursts (GRBs) via peak energy–peak luminosity relation (so-called Yonetoku relation), and obtain constraints on cosmological parameters including dynamical dark energy parametrized by P/ρ≡w(z) =w0+wa×z/(1 +z). It is found that the current GRB data are consistent with the concordance model (Ωm= 0.28, ΩΛ= 0.72, w0=-1, wa= 0) within 2σ level. Although constraints from GRBs themselves are not so strong, they can improve the conventional constraints from type Ia supernovae because GRBs have much higher redshifts. Further, we estimate the constraints on the dark energy parameters expected by future observations with Gamma-ray Large Area Space Telescope and Swift by Monte Carlo simulation. Constraints would improve substantially with another 150 GRBs.

Gamma-ray bursts in 1.8 < z < 5.6 suggest that the time variation of the dark energy is small

Abstract We calibrated the peak energy–peak luminosity relation of gamma-ray bursts (GRBs; the so-called Yonetoku relation) using 33 events with redshift z < 1.62 without assuming any cosmological models. The luminosity distances to GRBs are estimated from those of large numbers of Type Ia supernovae with z < 1.755. This calibrated Yonetoku relation can be used as a new cosmic distance ladder towards higher redshifts. We determined the luminosity distances of 30 GRBs in 1.8 < z < 5.6 using the calibrated relation, and plotted the likelihood contour in the (Ωm, ΩΛ) plane. We obtained (Ωm, ΩΛ) = (0.37+0.14−0.11, 0.63+0.11−0.14) for a flat universe. Because our method is free from the circularity problem, we can say that our universe in 1.8 < z < 5.6 is compatible with the so-called concordance cosmological model derived for z < 1.8. This suggests that the time variation of the dark energy is small or zero up to z∼ 6.

Correlations between Lag, Luminosity, and Duration in Gamma-Ray Burst Pulses

We derive a new peak lag versus peak luminosity relation in gamma-ray burst (GRB) pulses. We demonstrate conclusively that GRB spectral lags are pulse rather than burst properties and show how the lag versus luminosity relation determined from CCF measurements of burst properties is essentially just a rough measure of this newly derived relation for individual pulses. We further show that most GRB pulses have correlated properties: short-lag pulses have shorter durations, are more luminous, and are harder within a burst than long-lag pulses. We also uncover a new pulse duration versus pulse peak luminosity relation, and indicate that long-lag pulses often precede short-lag pulses. Although most pulse behaviors are supportive of internal shocks (including long-lag pulses), we identify some pulse shapes that could result from external shocks.

Possible observational evidence for the -2 angular distribution of the opening half-angle of gamma-ray burst jets

We propose a method to estimate the jet opening half-angle of gamma-ray bursts (GRBs) using the spectral peak energy (Ep)-peak luminosity relation (the so-called Yonetoku relation) as well as the Ep-collimation-corrected gamma-ray energy relation (the so-called Ghirlanda relation). For bursts with known jet break times and redshifts, we have compared the derived jet opening half-angle with that measured and found that the differences are within a factor of 2. We apply the method to 689 long GRBs. We have found that the distribution function of the derived jet opening half-angle obeys f(θj) ∝θ−2.2±0.2j, although a lognormal fit is also possible. θ−2 distribution is compatible with the structured jet model. From the distribution function we have found that the beaming correction for the rate of GRBs is ∼340, which means ∼10−5 yr−1 galaxy−1 or only one in 102 Type Ib/c supernovae. We have also found the evolution of the distribution function as a function of the redshift.

Gamma‐Ray Burst Formation Rate Inferred from the Spectral Peak Energy–Peak Luminosity Relation

We investigate the GRB formation rate based on the relation between the spectral peak energy ($E_{p}$) and the isotropic luminosity. The $E_{p}$--luminosity relation covers the energy range of 50 -- 2000 keV and the luminosity range of $10^{50}$--$10^{54} erg/s, respectively. We find that the relation is considerably tighter than similar relations suggested previously. Using $E_{p}$--luminosity relation, we estimate the luminosity and the redshift of 684 GRBs with the unknown distances and derive the GRB formation rate as a function of the redshift. For $0 \le z \le 2$, the GRB formation rate is well correlated with the star formation rate while it increases monotonously from $z\sim 2$ out to $z \sim 12$. This behavior is consistent with the results of previous works using the lag--luminosity relation or the variability--luminosity relation.