Photometric redshifts for gamma-ray burst afterglows from GROND and<i>Swift</i>/UVOT

Krühler, T.; Schady, P.; Greiner, J.; Afonso, P.; Bottacini, E.; Clemens, C.; Filgas, R.; Klose, S.; Koch, T. S.; Kupcu-Yoldas, A.; Oates, S. R.; Page, M. J.; McBreen, S.; Nardini, M.; Guelbenzu, A. Nicuesa; Rau, A.; Roming, P. W. A.; Rossi, A.; Updike, A. C.; Yoldaş, A.

doi:10.1051/0004-6361/201015327

Cited by 58 publications

(72 citation statements)

References 138 publications

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“…The other important factor to consider is that the total SED is obtained by combining the UVOT and GROND data, which are two different instruments, which thus need to be calibrated against each other. Krühler et al (2011) performed this task by combining Swift-UVOT and GROND filter curves, utilizing their spectral overlap and established the following calibration relationship:…”

Section: Variability Correctionmentioning

confidence: 99%

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Kaur

Rau

Ajello

et al. 2016

ApJ

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Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broadband filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESOʼs La Silla Observatory. The wavelength range covered by these 13 filters extends from far-ultraviolet to the near-infrared. We report results on 40 new Fermidetected BL Lacs with the photometric redshiftdeterminations for fivesources, with 3FGL J1918.2-4110 being the most distant in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the gamma-ray horizon due to the extragalactic background light.

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Section: Variability Correctionmentioning

confidence: 99%

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Kaur

Rau

Ajello

et al. 2016

ApJ

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“…We applied Eq. (5) from Krühler et al (2011) to evaluate the amplitude of a possible systematic offset between UVOT and GROND data. Since the result is consistent within 2 sigma for all SEDs, we did not apply any correction to the different data sets and conclude that the instrumental cross-calibration is reliable within measurement uncertainties.…”

Section: Near-infrared To X-ray Sedmentioning

confidence: 99%

Afterglow rebrightenings as a signature of a long-lasting central engine activity?

Nardini

Elliott

Filgas

et al. 2014

A&A

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Context. In the past few years the number of well-sampled optical to near-infrared (NIR) light curves of long gamma-ray bursts (GRBs) has greatly increased, particularly due to simultaneous multi-band imagers such as GROND. Combining these densely sampled ground-based data sets with the Swift UVOT and XRT space observations unveils a much more complex afterglow evolution than what was predicted by the most commonly invoked theoretical models. GRB 100814A represents a remarkable example of these interesting well-sampled events, showing a prominent late-time rebrightening in the optical to NIR bands and a complex spectral evolution. This represents a unique laboratory to test the different afterglow emission models. Aims. Here we study the nature of the complex afterglow emission of GRB 100814A in the framework of different theoretical models. Moreover, we compare the late-time chromatic rebrightening with those observed in other well-sampled long GRBs. Methods. We analysed the optical and NIR observations obtained with the seven-channel Gamma-Ray burst Optical and Near-infrared Detector (GROND) at the 2.2 m MPG/ESO telescope together with the X-ray and UV data detected by the instruments onboard the Swift observatory. The broad-band afterglow evolution, achieved by constructing multi-instrument light curves and spectral energy distributions, is discussed in the framework of different theoretical models. Results. We find that the standard models that describe the broad-band afterglow emission within the external shock scenario fail to describe the complex evolution of GRB 100814A, and therefore more complex scenarios must be invoked. The analysis of the very well sampled broad-band light curve of GRB 100814A allowed us to deduce that models invoking late-time activity of the central engine in the observed afterglow emission are the preferred ones for all the different observed features. This late-time activity most likely has the form of a delayed reactivation of the ejecta emission process. However, a more detailed modelling of the radiative mechanisms associated with these scenarios is necessary to arrive at a firm conclusion on the nature of the optical rebrightenings that so often are detected in long GRBs.

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“…( 1) which is valid for −1 ≤ (g − r ) ≤ 2 (Krühler et al 2011). These corrections, Δmag GR→UV (Table 2), were calculated for all sources with accurate photometry in b, g , and r (δm < 0.2 mag).…”

Section: Variability Correctionmentioning

confidence: 99%

BL Lacertae objects beyond redshift 1.3 – UV-to-NIR photometry and photometric redshift forFermi/LAT blazars

Rau

Schady

Greiner

et al. 2012

A&A

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113

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Context. Observations of the γ-ray sky with Fermi led to significant advances towards understanding blazars, the most extreme class of active galactic nuclei. A large fraction of the population detected by Fermi is formed by BL Lacertae (BL Lac) objects, whose sample has always suffered from a severe redshift incompleteness due to the quasi-featureless optical spectra. Aims. Our goal is to provide a significant increase of the number of confirmed high-redshift BL Lac objects contained in the 2 LAC Fermi/LAT cataloge. Methods. For 103 Fermi/LAT blazars, photometric redshifts using spectral energy distribution fitting have been obtained. The photometry includes 13 broad-band filters from the far ultraviolet to the near-IR observed with Swift/UVOT and the multi-channel imager GROND at the MPG/ESO 2.2 m telescope. Data have been taken quasi-simultaneously and the remaining source-intrinsic variability has been corrected for. Results. We release the UV-to-near-IR 13-band photometry for all 103 sources and provide redshift constraints for 75 sources without previously known redshift. Out of those, eight have reliable photometric redshifts at z > ∼ 1.3, while for the other 67 sources we provide upper limits. Six of the former eight are BL Lac objects, which quadruples the sample of confirmed high-redshift BL Lac. This includes three sources with redshifts higher than the previous record for BL Lac, including CRATES J0402-2615, with the best-fit solution at z ≈ 1.9.

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

Cited by 58 publications

References 138 publications

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Afterglow rebrightenings as a signature of a long-lasting central engine activity?

BL Lacertae objects beyond redshift 1.3 – UV-to-NIR photometry and photometric redshift forFermi/LAT blazars

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