Clustering of the optical-afterglow luminosities of long gamma-ray bursts

Nardini, M.; Ghisellini, G.; Ghirlanda, G.; Tavecchio, F.; Firmani, C.; Lazzati, Davide

doi:10.1051/0004-6361:20054085

Cited by 77 publications

(128 citation statements)

References 93 publications

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“…In the late afterglow, ν i < ν c (the slow cooling regime) and the optical wavelength range is located either above or below ν c , which is fully supported by current observations (e.g. Galama & Wijers 2001;Stratta et al 2004;Nardini et al 2006;Schady et al 2007;Greiner et al 2011). Two prominent signatures, the Ly-α and Lyman-limit break at 121.5 × (1 + z) nm and 91.2 × (1 + z) nm respectively, and their characteristic redshift-dependent prominence, allow for a robust and precise redshift determination.…”

Section: Introductionsupporting

confidence: 85%

Photometric redshifts for gamma-ray burst afterglows from GROND andSwift/UVOT

Krühler

Schady

Greiner

et al. 2011

A&A

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Aims. We present a framework to obtain photometric redshifts (photo-zs) for gamma-ray burst afterglows. Using multi-band photometry from GROND and Swift/UVOT, photo-zs are derived for five GRBs for which spectroscopic redshifts are not available. Methods. We use UV/optical/NIR data and synthetic photometry based on afterglow observations and theory to derive the photometric redshifts of GRBs and their accuracy. Taking into account the afterglow synchrotron emission properties, we investigate the application of photometry to derive redshifts in a theoretical range between z ∼ 1 to z ∼ 12.Results. The measurement of photo-zs for GRB afterglows provides a quick, robust and reliable determination of the distance scale to the burst, particularly in those cases where spectroscopic observations in the optical/NIR range cannot be obtained. Given a sufficiently bright and mildly reddened afterglow, the relative photo-z accuracy η = Δz/(1 + z) is better than 10% between z = 1.5 and z ∼ 7 and better than 5% between z = 2 and z = 6. We detail the approach on 5 sources without spectroscopic redshifts observed with UVOT on-board Swift and/or GROND. The distance scale to those same afterglows is measured to be z = 4.31 +0.14 −0.15 for GRB 080825B, z = 2.13 +0.14 −0.20 for GRB 080906, z = 3.44 +0.15 −0.32 for GRB 081228, z = 2.03 +0.16 −0.14 for GRB 081230 and z = 1.28 +0.16 −0.15 for GRB 090530. Conclusions. Due to the exceptional luminosity and simple continuum spectrum of GRB afterglows, photometric redshifts can be obtained to an accuracy as good as η ∼ 0.03 over a large redshift range including robust (η ∼ 0.1) measurements in the ultra-high redshift regime (z 7). Combining the response from UVOT with ground-based observatories and in particular GROND operating in the optical/NIR wavelength regime, reliable photo-zs can be obtained from z ∼ 1.0 out to z ∼ 10, and possibly even at higher redshifts in some favorable cases, provided that these GRBs exist, are localized quickly, have sufficiently bright afterglows and are not heavily obscured.

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Section: Introductionsupporting

confidence: 85%

Photometric redshifts for gamma-ray burst afterglows from GROND andSwift/UVOT

Krühler

Schady

Greiner

et al. 2011

A&A

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“…The simplest observation is that the luminosity light curves, in both the X-ray and optical/UV samples, show clustered behaviour. Evidence for clustering into two groups, at ∼ 0.5 − 1 day, for the optical/IR GRB afterglows was reported by Boër & Gendre (2000); Gendre & Boër (2005); Nardini et al (2006); Liang & Zhang (2006); Nardini, Ghisellini & Ghirlanda (2008); . However, several more recently published works have suggested that the afterglow distributions are unimodal (Melandri et al 2008;Cenko et al 2009a;Oates et al 2009;Kann et al 2010;Melandri et al 2014).…”

Section: Introductionmentioning

confidence: 89%

Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation

Oates

Racusin

Pasquale

et al. 2015

Mon. Not. R. Astron. Soc.

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In this paper we further investigate the relationship, reported by Oates et al. (2012), between the optical/UV afterglow luminosity (measured at restframe 200 s) and average afterglow decay rate (measured from restframe 200 s onwards) of long duration Gamma-ray Bursts (GRBs). We extend the analysis by examining the X-ray light curves, finding a consistent correlation. We therefore explore how the parameters of these correlations relate to the prompt emission phase and, using a Monte Carlo simulation, explore whether these correlations are consistent with predictions of the standard afterglow model. We find significant correlations between: log L O,200s and log L X,200s ; α O,>200s and α X,>200s , consistent with simulations. The model also predicts relationships between log E iso and log L 200,s , however, while we find such relationships in the observed sample, the slope of the linear regression is shallower than that simulated and inconsistent at 3σ. Simulations also do not agree with correlations observed between log L 200s and α >200s , or log E iso and α >200s . Overall, these observed correlations are consistent with a common underlying physical mechanism producing GRBs and their afterglows regardless of their detailed temporal behaviour. However, a basic afterglow model has difficulty explaining all the observed correlations. This leads us to briefly discuss alternative more complex models.

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“…It should, therefore, be kept in mind that the results presented in this paper apply to GRBs with low host galaxy extinction along the line-of-sight (A V < ∼ 1.0). In the case of selection effects against dim GRBs, our results will be affected if low-luminosity GRBs belong to a different class of GRB than to their high-luminosity counterparts, as suggested by Liang & Zhang (2006) and Nardini et al (2006Nardini et al ( , 2008; although see Oates et al 2009) so this possibility should be kept in mind. We, therefore, stress that the results presented in this paper may not apply to low-luminosity and/or highly extinguished GRBs.…”

Section: Samplementioning

confidence: 96%

The missing gas problem in GRB host galaxies: evidence for a highly ionised component

Schady¹,

Savaglio²,

Kruehler³

et al. 2010

A&A

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There is considerable discrepancy between the amount of X-ray absorption and what is inferred from optical (rest frame UV) as measured along gamma-ray burst (GRB) sight lines, with the former typically an order of magnitude higher than what would be expected from the measurement of neutral element species via optical absorption line spectroscopy. We explored this "missing gas problem" in a sample of 29 GRBs with redshifts in the range 0.7-6.3 by studying the X-ray and optical spectra, as well as the afterglow broadband spectral energy distributions. The low ionisation species detected in the UV are associated with the neutral interstellar medium in the GRB host galaxy, while soft X-ray absorption, which is weakly dependent on the ionisation state of the gas, provides a probe of the total column of gas along the sight line. After careful consideration of any systematic effects, we find that the neutral gas consists of 10% of the total gas, and this limit decreases the more ionised the X-ray absorbing gas is, which in our spectral fits is assumed to be neutral. Only a very small fraction of this ionised gas, however, is detected in UV absorption lines with ionisation potentials up to ∼200 eV (i.e. Si iv, C iv, N v, O vi), which leaves us to postulate that the X-ray excess comes from ultra-highly-ionised, dense gas in the GRB vicinity.

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Clustering of the optical-afterglow luminosities of long gamma-ray bursts

Cited by 77 publications

References 93 publications

Photometric redshifts for gamma-ray burst afterglows from GROND andSwift/UVOT

Photometric redshifts for gamma-ray burst afterglows from GROND andSwift/UVOT

Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation

The missing gas problem in GRB host galaxies: evidence for a highly ionised component

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