arXiv subjects

Shulei Cao

Publications and source records attributed to Shulei Cao.

28 records · Page 2Linked to original sources

arXiv2022

Standardizing reverberation-measured C IV time-lag quasars, and using them with standardized Mg II quasars to constrain cosmological parameters

We use 38 C IV quasar (QSO) reverberation-mapped (RM) observations, which span eight orders of magnitude in luminosity and the redshift range $0.001064 \leq z \leq 3.368$, to simultaneously constrain cosmological-model and QSO radius-luminosity ($R-L$) relation parameters in six cosmological models, using an improved technique that more correctly accounts for the asymmetric errors bars of the time-lag measurements. We find that $R-L$ relation parameters are independent of the cosmological models used in the analysis and so the $R-L$ relation can be used to standardize the C IV QSOs. The C IV QSO cosmological constraints are consistent with those from Mg II QSOs, allowing us to derive joint C IV + Mg II QSO cosmological constraints which are consistent with currently accelerated cosmological expansion, as well as consistent with cosmological constraints derived using better-established baryon acoustic oscillation (BAO) and Hubble parameter [$H(z)$] measurements. When jointly analyzed with $H(z)$ + BAO data, current C IV + Mg II QSO data mildly tighten current $H(z)$ + BAO data cosmological constraints.

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arXiv2022

Gamma-ray burst data strongly favor the three-parameter fundamental plane (Dainotti) correlation relation over the two-parameter one

Gamma-ray bursts (GRBs), observed to redshift $z=9.4$, are potential probes of the largely unexplored $z\sim 2.7-9.4$ part of the early Universe. Thus, finding relevant relations among GRB physical properties is crucial. We find that the Platinum GRB data compilation, with 50 long GRBs (with relatively flat plateaus and no flares) in the redshift range $0.553 \leq z \leq 5.0$, and the LGRB95 data compilation, with 95 long GRBs in $0.297 \leq z \leq 9.4$, as well as the 145 GRB combination of the two, strongly favor the three-dimensional (3D) fundamental plane (Dainotti) correlation relation (between the peak prompt lumininosity, the luminosity at the end of the plateau emission, and its rest frame duration) over the two-dimensional one (between the luminosity at the end of the plateau emission and its duration). The 3D Dainotti correlations in the three data sets are standardizable. We find that while LGRB95 data have $\sim50$% larger intrinsic scatter parameter values than the better-quality Platinum data, they provide somewhat tighter constraints on cosmological-model and GRB-correlation parameters, perhaps solely due to the larger number of data points, 95 versus 50. This suggests that when compiling GRB data for the purpose of constraining cosmological parameters, given the quality of current GRB data, intrinsic scatter parameter reduction must be balanced against reduced sample size.

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arXiv2022

Using lower-redshift, non-CMB, data to constrain the Hubble constant and other cosmological parameters

We use updated Hubble parameter and baryon acoustic oscillation data, as well as other lower-redshift Type Ia supernova, Mg II reverberation-measured quasar, quasar angular size, H II starburst galaxy, and Amati-correlated gamma-ray burst data, to jointly constrain cosmological parameters in six cosmological models. The joint analysis provides model-independent determinations of the Hubble constant, $H_0=69.7\pm1.2$ $\rm{km \ s^{-1} \ Mpc^{-1}}$, and the current non-relativistic matter density parameter, $Ω_{m0}=0.295\pm0.017$. These error bars are factors of 2.2 and 2.3 larger than the corresponding error bars in the flat $Λ$CDM model from Planck TT,TE,EE+lowE+lensing cosmic microwave background anisotropy data. Based on the deviance information criterion (DIC), the flat $Λ$CDM model is most favored but mild dark energy dynamics and a little spatial curvature are not ruled out.

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arXiv2022

Standardizing Platinum Dainotti-correlated gamma-ray bursts, and using them with standardized Amati-correlated gamma-ray bursts to constrain cosmological model parameters

We show that the Platinum gamma-ray burst (GRB) data compilation, probing the redshift range $0.553 \leq z \leq 5.0$, obeys a cosmological-model-independent three-parameter fundamental plane (Dainotti) correlation and so is standardizable. While they probe the largely unexplored $z \sim 2.3-5$ part of cosmological redshift space, the GRB cosmological parameter constraints are consistent with, but less precise than, those from a combination of baryon acoustic oscillation (BAO) and Hubble parameter [$H(z)$] data. In order to increase the precision of GRB-only cosmological constraints, we exclude common GRBs from the larger Amati-correlated A118 data set composed of 118 GRBs and jointly analyze the remaining 101 Amati-correlated GRBs with the 50 Platinum GRBs. This joint 151 GRB data set probes the largely unexplored $z \sim 2.3-8.2$ region; the resulting GRB-only cosmological constraints are more restrictive, and consistent with, but less precise than, those from $H(z)$ + BAO data.

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arXiv2021

Standardizing Dainotti-correlated gamma-ray bursts, and using them with standardized Amati-correlated gamma-ray bursts to constrain cosmological model parameters

We show that each of the three Dainotti-correlated gamma-ray burst (GRB) data sets recently compiled by Wang et al. and Hu et al., that together probe the redshift range $0.35 \leq z \leq 5.91$, obey cosmological-model-independent Dainotti correlation relations and so are standardizable. We use these GRB data in conjunction with the best currently-available Amati-correlated GRB data, that probe $0.3399 \leq z \leq 8.2$, to constrain cosmological model parameters. The resulting cosmological constraints are weak, providing lower limits on the non-relativistic matter density parameter, mildly favoring non-zero spatial curvature, and largely consistent with currently accelerated cosmological expansion as well as with constraints determined from better-established data.

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arXiv2021

Cosmological constraints from HII starburst galaxy, quasar angular size, and other measurements

We compare the constraints from two (2019 and 2021) compilations of HII starburst galaxy (HIIG) data and test the model-independence of quasar angular size (QSO) data using six spatially flat and non-flat cosmological models. We find that the new 2021 compilation of HIIG data generally provides tighter constraints and prefers lower values of cosmological parameters than those from the 2019 HIIG data. QSO data by themselves give relatively model-independent constraints on the characteristic linear size, $l_{\rm m}$, of the QSOs within the sample. We also use Hubble parameter ($H(z)$), baryon acoustic oscillation (BAO), Pantheon Type Ia supernova (SN Ia) apparent magnitude (SN-Pantheon), and DES-3yr binned SN Ia apparent magnitude (SN-DES) measurements to perform joint analyses with HIIG and QSO angular size data, since their constraints are not mutually inconsistent within the six cosmological models we study. A joint analysis of $H(z)$, BAO, SN-Pantheon, SN-DES, QSO, and the newest compilation of HIIG data provides almost model-independent summary estimates of the Hubble constant, $H_0=69.7\pm1.2\ \rm{km \ s^{-1} \ Mpc^{-1}}$, the non-relativistic matter density parameter, $Ω_{\rm m_0}=0.293\pm0.021$, and $l_{\rm m}=10.93\pm0.25$ pc.

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arXiv2021

Using Pantheon and DES supernova, baryon acoustic oscillation, and Hubble parameter data to constrain the Hubble constant, dark energy dynamics, and spatial curvature

We use Pantheon Type Ia supernova (SN Ia) apparent magnitude, DES-3yr binned SN Ia apparent magnitude, Hubble parameter, and baryon acoustic oscillation measurements to constrain six spatially flat and non-flat cosmological models. These sets of data provide mutually consistent cosmological constraints in the six cosmological models we study. A joint analysis of these data sets provides model-independent estimates of the Hubble constant, $H_0=68.8\pm1.8\ \rm{km \ s^{-1} \ Mpc^{-1}}$, and the non-relativistic matter density parameter, $Ω_{\rm m_0}=0.294\pm0.020$. Although the joint constraints prefer mild dark energy dynamics and a little spatial curvature, they do not rule out dark energy being a cosmological constant and flat spatial hypersurfaces. We also add quasar angular size and H II starburst galaxy measurements to the combined data set and find more restrictive constraints.

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arXiv2021

Cosmological Constraints on the Coupling Model from Observational Hubble Parameter and Baryon Acoustic Oscillation Measurements

In the paper, we consider two models in which dark energy is coupled with either dust matter or dark matter, and discuss the conditions that allow more time for structure formation to take place at high redshifts. These models are expected to have a larger age of the universe than that of $Λ$CDM [universe consists of cold dark matter (CDM) and dark energy (a cosmological constant, $Λ$)], so it can explain the formation of high redshift gravitationally bound systems which the $Λ$CDM model cannot interpret. We use the observational Hubble parameter data (OHD) and Hubble parameter obtained from cosmic chronometers method ($H(z)$) in combination with baryon acoustic oscillation (BAO) data to constrain these models. With the best-fitting parameters, we discuss how the age, the deceleration parameter, and the energy density parameters evolve in the new universes, and compare them with that of $Λ$CDM.

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arXiv2020

Cosmological constraints from higher-redshift gamma-ray burst, HII starburst galaxy, and quasar (and other) data

We use higher-redshift gamma-ray burst (GRB), HII starburst galaxy (HIIG), and quasar angular size (QSO-AS) measurements to constrain six spatially flat and non-flat cosmological models. These three sets of cosmological constraints are mutually consistent. Cosmological constraints from a joint analysis of these data sets are largely consistent with currently-accelerating cosmological expansion as well as with cosmological constraints derived from a combined analysis of Hubble parameter ($H(z)$) and baryon acoustic oscillation (BAO, with Planck-determined baryonic matter density) measurements. A joint analysis of the $H(z)$ + BAO + QSO-AS + HIIG + GRB data provides fairly model-independent determinations of the non-relativistic matter density parameter $Ω_{\rm m_0}=0.313\pm0.013$ and the Hubble constant $H_0=69.3\pm1.2\ \rm{km \ s^{-1} \ Mpc^{-1}}$. These data are consistent with the dark energy being a cosmological constant and with spatial hypersurfaces being flat, but they do not rule out mild dark energy dynamics or a little spatial curvature. We also investigate the effect of including quasar flux measurements in the mix and find no novel conclusions.

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arXiv2020

Cosmological constraints from HII starburst galaxy apparent magnitude and other cosmological measurements

We use HII starburst galaxy apparent magnitude measurements to constrain cosmological parameters in six cosmological models. A joint analysis of HII galaxy, quasar angular size, baryon acoustic oscillations peak length scale, and Hubble parameter measurements result in relatively model-independent and restrictive estimates of the current values of the non-relativistic matter density parameter $Ω_{\rm m_0}$ and the Hubble constant $H_0$. These estimates favor a 2.0$σ$ to 3.4$σ$ (depending on cosmological model) lower $H_0$ than what is measured from the local expansion rate. The combined data are consistent with dark energy being a cosmological constant and with flat spatial hypersurfaces, but do not strongly rule out mild dark energy dynamics or slightly non-flat spatial geometries.

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