Are<i>Swift</i>gamma-ray bursts consistent with the Ghirlanda relation?

Campana, S.; Guidorzi, C.; Tagliaferri, G.; Chincarini, G.; Moretti, A.; Rizzuto, Debora; Romano, P.

doi:10.1051/0004-6361:20066984

Cited by 38 publications

(40 citation statements)

References 68 publications

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“…Furthermore these very luminous GRBs with high values of the redshift corrected E peak are not compatible with the E peak,i − E γ relationship as shown in Fig. 13 which was obtained for GRBs with in general lower values of the peak energy (Ghirlanda et al 2004;Campana et al 2007). While being consistent with the Amati (E peak,i − E iso ) relation at the 2σ level (see also Amati et al 2009), albeit with a large scatter (see also e.g.…”

Section: Afterglow Properties and Energeticsmentioning

confidence: 73%

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

McBreen

Krühler

Rau

et al. 2010

A&A

114

100

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Aims. Fermi can measure the spectral properties of gamma-ray bursts over a very large energy range and is opening a new window on the prompt emission of these energetic events. Localizations by the instruments on Fermi in combination with follow-up by Swift provide accurate positions for observations at longer wavelengths leading to the determination of redshifts, the true energy budget, host galaxy properties and facilitate comparison with pre-Fermi bursts. Methods. Multi-wavelength follow-up observations were performed on the afterglows of four bursts with high energy emission detected by Fermi/LAT: GRB 090323, GRB 090328, GRB 090510 and GRB 090902B. They were obtained in the optical/near-infrared bands with GROND mounted at the MPG/ESO 2.2 m telescope and additionally of GRB 090323 in the optical with the 2 m telescope in Tautenburg, Germany. Three of the events are classified as long bursts while GRB 090510 is a well localized short GRB with GeV emission. In addition, host galaxies were detected for three of the four bursts. Spectroscopic follow-up was initiated with the VLT for GRB 090328 and GRB 090510. Results. The afterglow observations in 7 bands are presented for all bursts and their host galaxies are investigated. Knowledge of the distance and the local dust extinction enables comparison of the afterglows of LAT-detected GRBs with the general sample. The spectroscopic redshifts of GRB 090328 and GRB 090510 were determined to be z = 0.7354 ± 0.0003 and z = 0.903 ± 0.001 and dust corrected star-formation rates of 4.8 M yr −1 and 0.60 M yr −1 were derived for their host galaxies, respectively. Conclusions. The afterglows of long bursts exhibit power-law decay indices (α) from less than 1 to ∼2.3 and spectral indices (β opt ) values from 0.65 to ∼1.2 which are fairly standard for GRB afterglows. Constraints are placed on the jet half opening angles of < ∼ 2.1 • to > ∼ 6.4 • , which allows limits to be placed on the beaming corrected energies. These range from < ∼ 5 × 10 50 erg to the one of the highest values ever recorded, > ∼ 2.2 × 10 52 erg for GRB 090902B, and are not consistent with a standard candle. The extremely energetic long Fermi bursts have optical afterglows which lie in the top half of the brightness distribution of all optical afterglows detected in the Swift era or even in the top 5% if incompleteness is considered. The properties of the host galaxies of these LAT detected bursts in terms of extinction, star formation rates and masses do not appear to differ from previous samples.

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Section: Afterglow Properties and Energeticsmentioning

confidence: 73%

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

McBreen

Krühler

Rau

et al. 2010

A&A

114

100

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“…Thus, particular care and sophisticated statistical methodologies have to be adopted in order to avoid circularity problems when constructing a GRB Hubble diagram. In addition, recent analyses based on updated samples of GRBs showed that the dispersion of three‐parameter correlations could be significantly larger than thought before (Campana et al 2007; Ghirlanda et al 2007; Rossi et al 2008).…”

Section: Introductionmentioning

confidence: 90%

Measuring the cosmological parameters with theE_p,i-E_isocorrelation of gamma-ray bursts

Amati

Guidorzi

Frontera

et al. 2008

Monthly Notices of the Royal Astronomical Society

371

428

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We have used the Ep,i–Eiso correlation of gamma‐ray bursts (GRBs) to measure the cosmological parameter ΩM. By adopting a maximum likelihood approach which allows us to correctly quantify the extrinsic (i.e. non‐Poissonian) scatter of the correlation, we constrain (for a flat universe) ΩM to 0.04–0.40 (68 per cent confidence level), with a best‐fitting value of ΩM∼ 0.15, and exclude ΩM= 1 at >99.9 per cent confidence level. If we release the assumption of a flat universe, we still find evidence for a low value of ΩM (0.04–0.50 at 68 per cent confidence level) and a weak dependence of the dispersion of the Ep,i–Eiso correlation on ΩΛ (with an upper limit of ΩΛ∼ 1.15 at 90 per cent confidence level). Our approach makes no assumptions on the Ep,i–Eiso correlation and it does not use other calibrators to set the ‘zero’ point of the relation, therefore our treatment of the data is not affected by circularity and the results are independent of those derived via Type Ia supernovae (or other cosmological probes). Unlike other multi‐parameters correlations, our analysis grounds on only two parameters, then including a larger number (a factor of ∼3) of GRBs and being less affected by systematics. Simulations based on realistic extrapolations of ongoing (and future) GRB experiments (e.g. Swift, Konus‐Wind, GLAST) show that: (i) the uncertainties on cosmological parameters can be significantly decreased and (ii) future data will allow us to get clues on the ‘dark energy’ evolution.

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“…curves, the measurement of t b and its use to derive the jet opening angle are questionable (Campana et al 2007;Ghirlanda et al 2007). It was also proposed that the inclusion of the "high signal timescale", T 0.45 , introduced and used for variability studies, reduces the dispersion in the E p,i -E iso correlation , but this property was not confirmed by later studies (Rossi et al 2008;Collazzi & Schaefer 2008).…”

Section: Grb 080916c and Other Spectral Energy Correlationsmentioning

confidence: 99%

Extremely energetic Fermi gamma-ray bursts obey spectral energy correlations

Amati¹,

Frontera

Guidorzi

2009

A&A

Self Cite

201

235

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The origin, reliability, and dispersion of the E p,i -E iso and other spectral energy correlations is a highly debated topic in GRB astrophysics. GRB 080916C, with its enormous radiated energy (E iso ∼ 10 55 erg in the 1 keV−10 GeV cosmological rest-frame energy band) and its intense GeV emission measured by Fermi, provides a unique opportunity to investigate this issue. In our analysis, we also study another extremely energetic event, GRB 090323, more recently detected and localized by Fermi/LAT, whose radiated energy is comparable to that of GRB 080916C in the 1 keV−10 MeV energy range. Based on Konus/WIND and Fermi spectral measurements, we find that both events are fully consistent with the E p,i -E iso correlation (updated to include 95 GRBs with the data available as of April 2009), thus further confirming and extending it, and providing evidence against a possible flattening or increased dispersion at very high energies. This also suggests that the physics behind the emission of peculiarly bright and hard GRBs is the same as for medium-bright and soft-weak long events (XRFs), which all follow the correlation. In addition, we find that the normalization of the correlation obtained by considering these two GRBs and the other long ones for which E p,i was measured to high accuracy by the Fermi/GBM are fully consistent with those obtained by other instruments (e.g., BeppoSAX, Swift, Konus/WIND), thus indicating that the correlation is not affected significantly by "data truncation" because of detector thresholds and limited energy bands. A Fermi/GBM accurate estimate of the peak energy of a very bright and hard short GRB with a measured redshift, GRB 090510, provides robust evidence that short GRBs do not follow the E p,i -E iso correlation and that the E p,i -E iso plane can be used to discriminate between, and understand, the two classes of events. Prompted by the extension of the spectrum of GRB 080916C to several GeV (in the cosmological rest-frame) without any excess or cut-off, we also investigated whether the evaluation of E iso in the commonly adopted 1 keV−10 MeV energy band may bias the E p,i -E iso correlation and/or contribute to its scatter. By computing E iso from 1 keV to 10 GeV, the slope of the correlation becomes slightly flatter, while its dispersion does not change significantly. Finally, we find that GRB 080916C is also consistent with most of the other spectral energy correlations derived from it, with the possible exception of the E p,i -E iso -t b correlation.

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AreSwiftgamma-ray bursts consistent with the Ghirlanda relation?

Cited by 38 publications

References 68 publications

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

Measuring the cosmological parameters with theE_p,i-E_isocorrelation of gamma-ray bursts

Extremely energetic Fermi gamma-ray bursts obey spectral energy correlations

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AreSwiftgamma-ray bursts consistent with the Ghirlanda relation?

Cited by 38 publications

References 68 publications

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

Measuring the cosmological parameters with theEp,i-Eisocorrelation of gamma-ray bursts

Extremely energetic Fermi gamma-ray bursts obey spectral energy correlations

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Measuring the cosmological parameters with theE_p,i-E_isocorrelation of gamma-ray bursts