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Article: Measuring dark energy with the Eiso–Ep correlation of gamma-ray bursts using model-independent methods

TitleMeasuring dark energy with the Eiso–Ep correlation of gamma-ray bursts using model-independent methods
Authors
KeywordsCosmological parameters
Dark energy
Gamma rays: general
Issue Date2016
PublisherEDP Sciences. The Journal's web site is located at http://www.aanda.org
Citation
Astronomy & Astrophysics, 2016, v. 585, p. article no. A68 How to Cite?
AbstractWe use two model-independent methods to standardize long gamma-ray bursts (GRBs) using the Eiso − Ep correlation (log Eiso = a + blog Ep), where Eiso is the isotropic-equivalent gamma-ray energy and Ep is the spectral peak energy. We update 42 long GRBs and attempt to constrain the cosmological parameters. The full sample contains 151 long GRBs with redshifts from 0.0331 to 8.2. The first method is the simultaneous fitting method. We take the extrinsic scatter σext into account and assign it to the parameter Eiso. The best-fitting values are a = 49.15 ± 0.26, b = 1.42 ± 0.11, σext = 0.34 ± 0.03 and Ωm = 0.79 in the flat ΛCDM model. The constraint on Ωm is 0.55 < Ωm< 1 at the 1σ confidence level. If reduced χ2 method is used, the best-fit results are a = 48.96 ± 0.18, b = 1.52 ± 0.08, and Ωm = 0.50 ± 0.12. The second method uses type Ia supernovae (SNe Ia) to calibrate the Eiso − Ep correlation. We calibrate 90 high-redshift GRBs in the redshift range from 1.44 to 8.1. The cosmological constraints from these 90 GRBs are Ωm = 0.23+0.06-0.04 for flat ΛCDM and Ωm = 0.18 ± 0.11 and ΩΛ = 0.46 ± 0.51 for non-flat ΛCDM. For the combination of GRB and SNe Ia sample, we obtain Ωm = 0.271 ± 0.019 and h = 0.701 ± 0.002 for the flat ΛCDM and the non-flat ΛCDM, and the results are Ωm = 0.225 ± 0.044, ΩΛ = 0.640 ± 0.082, and h = 0.698 ± 0.004. These results from calibrated GRBs are consistent with that of SNe Ia. Meanwhile, the combined data can improve cosmological constraints significantly, compared to SNe Ia alone. Our results show that the Eiso − Ep correlation is promising to probe the high-redshift Universe.
Persistent Identifierhttp://hdl.handle.net/10722/222482
ISSN
2014 Impact Factor: 4.378
2015 SCImago Journal Rankings: 2.446

 

DC FieldValueLanguage
dc.contributor.authorWang, JS-
dc.contributor.authorWang, F-
dc.contributor.authorCheng, KS-
dc.contributor.authorDai, ZG-
dc.date.accessioned2016-01-18T07:41:09Z-
dc.date.available2016-01-18T07:41:09Z-
dc.date.issued2016-
dc.identifier.citationAstronomy & Astrophysics, 2016, v. 585, p. article no. A68-
dc.identifier.issn0004-6361-
dc.identifier.urihttp://hdl.handle.net/10722/222482-
dc.description.abstractWe use two model-independent methods to standardize long gamma-ray bursts (GRBs) using the Eiso − Ep correlation (log Eiso = a + blog Ep), where Eiso is the isotropic-equivalent gamma-ray energy and Ep is the spectral peak energy. We update 42 long GRBs and attempt to constrain the cosmological parameters. The full sample contains 151 long GRBs with redshifts from 0.0331 to 8.2. The first method is the simultaneous fitting method. We take the extrinsic scatter σext into account and assign it to the parameter Eiso. The best-fitting values are a = 49.15 ± 0.26, b = 1.42 ± 0.11, σext = 0.34 ± 0.03 and Ωm = 0.79 in the flat ΛCDM model. The constraint on Ωm is 0.55 < Ωm< 1 at the 1σ confidence level. If reduced χ2 method is used, the best-fit results are a = 48.96 ± 0.18, b = 1.52 ± 0.08, and Ωm = 0.50 ± 0.12. The second method uses type Ia supernovae (SNe Ia) to calibrate the Eiso − Ep correlation. We calibrate 90 high-redshift GRBs in the redshift range from 1.44 to 8.1. The cosmological constraints from these 90 GRBs are Ωm = 0.23+0.06-0.04 for flat ΛCDM and Ωm = 0.18 ± 0.11 and ΩΛ = 0.46 ± 0.51 for non-flat ΛCDM. For the combination of GRB and SNe Ia sample, we obtain Ωm = 0.271 ± 0.019 and h = 0.701 ± 0.002 for the flat ΛCDM and the non-flat ΛCDM, and the results are Ωm = 0.225 ± 0.044, ΩΛ = 0.640 ± 0.082, and h = 0.698 ± 0.004. These results from calibrated GRBs are consistent with that of SNe Ia. Meanwhile, the combined data can improve cosmological constraints significantly, compared to SNe Ia alone. Our results show that the Eiso − Ep correlation is promising to probe the high-redshift Universe.-
dc.languageeng-
dc.publisherEDP Sciences. The Journal's web site is located at http://www.aanda.org-
dc.relation.ispartofAstronomy & Astrophysics-
dc.rightsThe original publication is available at http://dx.doi.org/10.1051/0004-6361/201526485 or Credit: Wang, JS., Wang, F., Cheng, KS.& Dai, ZG, vol. 585, article no. A68, 2016, reproduced with permission, © ESO-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectCosmological parameters-
dc.subjectDark energy-
dc.subjectGamma rays: general-
dc.titleMeasuring dark energy with the Eiso–Ep correlation of gamma-ray bursts using model-independent methods-
dc.typeArticle-
dc.identifier.emailCheng, KS: hrspksc@hkucc.hku.hk-
dc.identifier.authorityCheng, KS=rp00675-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1051/0004-6361/201526485-
dc.identifier.hkuros256668-
dc.identifier.volume585-
dc.identifier.spagearticle no. A68-
dc.identifier.epagearticle no. A68-
dc.publisher.placeFrance-

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