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21 results on '"Pasquale, M. De"'

1. Dissecting the interstellar medium of a z = 6.3 galaxy

Author

Saccardi, A., Vergani, S.D., Cia, A. De, D’Elia, V., Heintz, K.E., Izzo, L., Palmerio, J.T., Petitjean, P., Rossi, A, Ugarte Postigo, A. de, Christensen, L., Konstantopoulou, C., Levan, A.J., Malesani, D., Møller, P., Ramburuth-Hurt, T., Salvaterra, R., Tanvir, N.R., Thöne, C.C., Vejlgaard, S., Fynbo, J.P.U., Kann, D.A., Schady, P., Watson, D.J., Wiersema, K., Campana, S., Covino, S., Pasquale, M. De, Fausey, H., Hartmann, D.H., Horst, A.J. van der, Jakobsson, P., Palazzi, E., Pugliese, G., Savaglio, S., Starling, R.L.C., Stratta, G., Zafar, T., Saccardi, A., Vergani, S.D., Cia, A. De, D’Elia, V., Heintz, K.E., Izzo, L., Palmerio, J.T., Petitjean, P., Rossi, A, Ugarte Postigo, A. de, Christensen, L., Konstantopoulou, C., Levan, A.J., Malesani, D., Møller, P., Ramburuth-Hurt, T., Salvaterra, R., Tanvir, N.R., Thöne, C.C., Vejlgaard, S., Fynbo, J.P.U., Kann, D.A., Schady, P., Watson, D.J., Wiersema, K., Campana, S., Covino, S., Pasquale, M. De, Fausey, H., Hartmann, D.H., Horst, A.J. van der, Jakobsson, P., Palazzi, E., Pugliese, G., Savaglio, S., Starling, R.L.C., Stratta, G., and Zafar, T.

Abstract

Contains fulltext : 290732.pdf (Publisher’s version ) (Open Access)

Published
2023

2. The ultra-long GRB 220627A at z = 3.08

Author

Wet, S. de, Izzo, L., Groot, P.J., Bisero, S., D’Elia, V., Pasquale, M. De, Hartmann, D.H., Heintz, K.E., Jakobsson, P., Laskar, T., Levan, Andrew, Martin-Carrillo, A., Melandri, A., Guelbenzu, A. Nicuesa, Pugliese, G., Rossi, A, Saccardi, A., Savaglio, S., Schady, P., Tanvir, N.R., Eerten, H. van, Vergani, S.D., Wet, S. de, Izzo, L., Groot, P.J., Bisero, S., D’Elia, V., Pasquale, M. De, Hartmann, D.H., Heintz, K.E., Jakobsson, P., Laskar, T., Levan, Andrew, Martin-Carrillo, A., Melandri, A., Guelbenzu, A. Nicuesa, Pugliese, G., Rossi, A, Saccardi, A., Savaglio, S., Schady, P., Tanvir, N.R., Eerten, H. van, and Vergani, S.D.

Abstract

Contains fulltext : 296445.pdf (Publisher’s version ) (Open Access)

Published
2023

3. A search for the afterglows, kilonovae, and host galaxies of two short GRBs: GRB 211106A and GRB 211227A

Author

Ferro, M., Brivio, R., D’Avanzo, P., Rossi, A, Izzo, L., Campana, S., Christensen, L., Dinatolo, M., Hussein, S., Levan, A.J., Melandri, A., Bernardini, M.G., Covino, S., D’Elia, V., Della Valle, M., Pasquale, M. De, Gompertz, B.P., Hartmann, D., Heintz, K.E., Jakobsson, P., Kouveliotou, C., Malesani, D.B., Martin-Carrillo, A., Nava, L., Nicuesa Guelbenzu, A., Pugliese, G., Salvaggio, C., Salvaterra, R., Savaglio, S., Sbarrato, T., Tanvir, N.R., Wijers, R.A.M.J., Zafar, T., Ferro, M., Brivio, R., D’Avanzo, P., Rossi, A, Izzo, L., Campana, S., Christensen, L., Dinatolo, M., Hussein, S., Levan, A.J., Melandri, A., Bernardini, M.G., Covino, S., D’Elia, V., Della Valle, M., Pasquale, M. De, Gompertz, B.P., Hartmann, D., Heintz, K.E., Jakobsson, P., Kouveliotou, C., Malesani, D.B., Martin-Carrillo, A., Nava, L., Nicuesa Guelbenzu, A., Pugliese, G., Salvaggio, C., Salvaterra, R., Savaglio, S., Sbarrato, T., Tanvir, N.R., Wijers, R.A.M.J., and Zafar, T.

Abstract

Item does not contain fulltext

Published
2023

4. The Peculiar Short-duration GRB 200826A and Its Supernova*

Author

Rossi, A., primary, Rothberg, B., additional, Palazzi, E., additional, Kann, D. A., additional, D’Avanzo, P., additional, Amati, L., additional, Klose, S., additional, Perego, A., additional, Pian, E., additional, Guidorzi, C., additional, Pozanenko, A. S., additional, Savaglio, S., additional, Stratta, G., additional, Agapito, G., additional, Covino, S., additional, Cusano, F., additional, D’Elia, V., additional, Pasquale, M. De, additional, Valle, M. Della, additional, Kuhn, O., additional, Izzo, L., additional, Loffredo, E., additional, Masetti, N., additional, Melandri, A., additional, Minaev, P. Y., additional, Guelbenzu, A. Nicuesa, additional, Paris, D., additional, Paiano, S., additional, Plantet, C., additional, Rossi, F., additional, Salvaterra, R., additional, Schulze, S., additional, Veillet, C., additional, and Volnova, A. A., additional

Published
2022
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5. A blast from the infant Universe: The very high-z GRB210905A

Author

Rossi, A, Frederiks, D.D., Kann, D.A., Pasquale, M. De, Pian, E., Lamb, G.P., Levan, A.J., Malesani, D., Pugliese, G., Xu, D., Zhang, J., Rossi, A, Frederiks, D.D., Kann, D.A., Pasquale, M. De, Pian, E., Lamb, G.P., Levan, A.J., Malesani, D., Pugliese, G., Xu, D., and Zhang, J.

Abstract

Contains fulltext : 282667.pdf (Publisher’s version ) (Open Access)

Published
2022

6. The Peculiar Short-duration GRB 200826A and Its Supernova

Author

Ministerio de Ciencia e Innovación (España), European Commission, Agenzia Spaziale Italiana, German Research Foundation, Rossi, A., Rothberg, B., Palazzi, E., Kann, D.A., D'Avanzo, P., Amati, L., Klose, S., Perego, A., Pian, E., Guidorzi, C., Pozanenko, A.S., Savaglio, S., Stratta, G., Agapito, G., Covino, Stefano, Cusano, F., D'Elia, V., Pasquale, M. de, Valle, M. Della, Kuhn, O., Izzo, L., Loffredo, E., Masetti, N., Melandri, A., Minaev, P.Y., Guelbenzu, A. Nicuesa, Paris, D., Paiano, S., Plantet, C., Rossi, F., Salvaterra, R., Schulze, S., Veillet, C., Volnova, A. A., Ministerio de Ciencia e Innovación (España), European Commission, Agenzia Spaziale Italiana, German Research Foundation, Rossi, A., Rothberg, B., Palazzi, E., Kann, D.A., D'Avanzo, P., Amati, L., Klose, S., Perego, A., Pian, E., Guidorzi, C., Pozanenko, A.S., Savaglio, S., Stratta, G., Agapito, G., Covino, Stefano, Cusano, F., D'Elia, V., Pasquale, M. de, Valle, M. Della, Kuhn, O., Izzo, L., Loffredo, E., Masetti, N., Melandri, A., Minaev, P.Y., Guelbenzu, A. Nicuesa, Paris, D., Paiano, S., Plantet, C., Rossi, F., Salvaterra, R., Schulze, S., Veillet, C., and Volnova, A. A.

Abstract

Gamma-ray bursts (GRBs) are classified into long and short events. Long GRBs (LGRBs) are associated with the end states of very massive stars, while short GRBs (SGRBs) are linked to the merger of compact objects. GRB 200826A was a peculiar event, because by definition it was an SGRB, with a rest-frame duration of ∼0.5 s. However, this event was energetic and soft, which is consistent with LGRBs. The relatively low redshift (z = 0.7486) motivated a comprehensive, multiwavelength follow-up campaign to characterize its host, search for a possible associated supernova (SN), and thus understand the origin of this burst. To this aim we obtained a combination of deep near-infrared (NIR) and optical imaging together with spectroscopy. Our analysis reveals an optical and NIR bump in the light curve whose luminosity and evolution are in agreement with several SNe associated to LGRBs. Analysis of the prompt GRB shows that this event follows the Ep,i–Eiso relation found for LGRBs. The host galaxy is a low-mass star-forming galaxy, typical of LGRBs, but with one of the highest star formation rates, especially with respect to its mass ($\mathrm{log}{M}_{* }/{M}_{\odot }=8.6$, SFR ∼ 4.0 M⊙ yr−1). We conclude that GRB 200826A is a typical collapsar event in the low tail of the duration distribution of LGRBs. These findings support theoretical predictions that events produced by collapsars can be as short as 0.5 s in the host frame and further confirm that duration alone is not an efficient discriminator for the progenitor class of a GRB. © 2022. The Author(s). Published by the American Astronomical Society.

Published
2022

7. The Central Engine of GRB 130831A and the Energy Breakdown of a Relativistic Explosion

Author

Pasquale, M. De, Oates, S. R, Racusin, J. L, Kann, D. A, Zhang, B, Pozanenko, A, Volnova, A.A, Trotter, A, Frank, N, and Cucchiara, A

Subjects
Astrophysics
Abstract

Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, yet the nature and physical properties of their energy sources are far from understood. Very important clues, however, can be inferred by studying the afterglows of these events. We present optical and X-ray observations of GRB 130831A obtained by Swift, Chandra, Skynet, Reionization And Transients Infra-Red camera, Maidanak, International Scientific Optical-Observation Network, Nordic Optical Telescope, Liverpool Telescope and Gran Telescopio Canarias. This burst shows a steep drop in the X-ray light curve at asymptotically equal to 10(exp 5) s after the trigger, with a power-law decay index of alpha that is approximately 6. Such a rare behaviour cannot be explained by the standard forward shock (FS) model and indicates that the emission, up to the fast decay at 10(exp 5) s, must be of internal origin, produced by a dissipation process within an ultrarelativistic outflow. We propose that the source of such an outflow, which must produce the X-ray flux for an asymptotically equal to 1 d in the cosmological rest frame, is a newly born magnetar or black hole. After the drop, the faint X-ray afterglow continues with a much shallower decay. The optical emission, on the other hand, shows no break across the X-ray steep decrease, and the late-time decays of both the X-ray and optical are consistent. Using both the X-ray and optical data, we show that the emission after an asymptotically equal to 10(exp 5) scan be explained well by the FS model. We model our data to derive the kinetic energy of the ejecta and thus measure the efficiency of the central engine of a GRB with emission of internal origin visible for a long time. Furthermore, we break down the energy budget of this GRB into the prompt emission, the late internal dissipation, the kinetic energy of the relativistic ejecta,and compare it with the energy of the associated supernova, SN 2013 fu.

Published
2014
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8. Swift Multiwavelength Follow-up of LVC S200224ca and the Implications for Binary Black Hole Mergers

Author

Klingler, N. J., Lien, A., Oates, S. R., Kennea, J. A., Evans, P. A., Tohuvavohu, A., Zhang, B., Page, K. L., Cenko, S. B., Barthelmy, S. D., Beardmore, A. P., Bernardini, M. G., Breeveld, A. A., Brown, P. J., Burrows, D. N., Campana, S., Cusumano, G., D’Aì, A., D’Avanzo, P., D’Elia, V., Pasquale, M. de, Emery, S. W. K., Garcia, Jeronimo, Giommi, P., Gronwall, C., Hartmann, D. H., Krimm, H. A., Kuin, N. P. M., Malesani, D. B., Marshall, F. E., Melandri, A., Nousek, J. A., O’Brien, P. T., Osborne, J. P., Palmer, D. M., Page, M. J., Perri, M., Racusin, J. L., Sakamoto, T., Sbarufatti, B., Schlieder, J. E., Siegel, M. H., Tagliaferri, G., Troja, E., Klingler, N. J., Lien, A., Oates, S. R., Kennea, J. A., Evans, P. A., Tohuvavohu, A., Zhang, B., Page, K. L., Cenko, S. B., Barthelmy, S. D., Beardmore, A. P., Bernardini, M. G., Breeveld, A. A., Brown, P. J., Burrows, D. N., Campana, S., Cusumano, G., D’Aì, A., D’Avanzo, P., D’Elia, V., Pasquale, M. de, Emery, S. W. K., Garcia, Jeronimo, Giommi, P., Gronwall, C., Hartmann, D. H., Krimm, H. A., Kuin, N. P. M., Malesani, D. B., Marshall, F. E., Melandri, A., Nousek, J. A., O’Brien, P. T., Osborne, J. P., Palmer, D. M., Page, M. J., Perri, M., Racusin, J. L., Sakamoto, T., Sbarufatti, B., Schlieder, J. E., Siegel, M. H., Tagliaferri, G., and Troja, E.

Abstract

On 2020 February 24, during their third observing run (“O3”), the Laser Interferometer Gravitational-wave Observatory and Virgo Collaboration detected S200224ca: a candidate gravitational wave (GW) event produced by a binary black hole (BBH) merger. This event was one of the best-localized compact binary coalescences detected in O3 (with 50%/90% error regions of 13/72 deg2), and so the Neil Gehrels Swift Observatory performed rapid near-UV/X-ray follow-up observations. Swift-XRT and UVOT covered approximately 79.2% and 62.4% (respectively) of the GW error region, making S200224ca the BBH event most thoroughly followed-up in near-UV (u-band) and X-ray to date. No likely EM counterparts to the GW event were found by the Swift BAT, XRT, or UVOT, nor by other observatories. Here, we report on the results of our searches for an EM counterpart, both in the BAT data near the time of the merger, and in follow-up UVOT/XRT observations. We also discuss the upper limits we can place on EM radiation from S200224ca, as well as the implications these limits have on the physics of BBH mergers. Namely, we place a shallow upper limit on the dimensionless BH charge, , and an upper limit on the isotropic-equivalent energy of a blast wave E <4.1 × 1051 erg (assuming typical GRB parameters).

Published
2021

9. Swift Multiwavelength Follow-up of LVC S200224ca and the Implications for Binary Black Hole Mergers

Author

Klingler, N. J., primary, Lien, A., additional, Oates, S. R., additional, Kennea, J. A., additional, Evans, P. A., additional, Tohuvavohu, A., additional, Zhang, B., additional, Page, K. L., additional, Cenko, S. B., additional, Barthelmy, S. D., additional, Beardmore, A. P., additional, Bernardini, M. G., additional, Breeveld, A. A., additional, Brown, P. J., additional, Burrows, D. N., additional, Campana, S., additional, Cusumano, G., additional, D’Aì, A., additional, D’Avanzo, P., additional, D’Elia, V., additional, Pasquale, M. de, additional, Emery, S. W. K., additional, Garcia, J., additional, Giommi, P., additional, Gronwall, C., additional, Hartmann, D. H., additional, Krimm, H. A., additional, Kuin, N. P. M., additional, Malesani, D. B., additional, Marshall, F. E., additional, Melandri, A., additional, Nousek, J. A., additional, O’Brien, P. T., additional, Osborne, J. P., additional, Palmer, D. M., additional, Page, M. J., additional, Perri, M., additional, Racusin, J. L., additional, Sakamoto, T., additional, Sbarufatti, B., additional, Schlieder, J. E., additional, Siegel, M. H., additional, Tagliaferri, G., additional, and Troja, E., additional

Published
2021
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10. Lyman continuum leakage in faint star-forming galaxies at redshift z = 3−3.5 probed by gamma-ray bursts⋆

Author

Vielfaure, J.-B., Vergani, S.D., Japelj, J., Fynbo, J.P.U., Gronke, M., Heintz, K.E., Malesani, D.B., Petitjean, P., Tanvir, N.R., D’Elia, V., Kann, D.A., Palmerio, J.T., Salvaterra, R., Wiersema, K., Arabsalmani, M., Campana, S., Covino, S., Pasquale, M. De, Ugarte Postigo, A. de, Hammer, F., Hartmann, D.H., Jakobsson, P., Kouveliotou, C., Laskar, T., Levan, A.J., Rossi, A, Vielfaure, J.-B., Vergani, S.D., Japelj, J., Fynbo, J.P.U., Gronke, M., Heintz, K.E., Malesani, D.B., Petitjean, P., Tanvir, N.R., D’Elia, V., Kann, D.A., Palmerio, J.T., Salvaterra, R., Wiersema, K., Arabsalmani, M., Campana, S., Covino, S., Pasquale, M. De, Ugarte Postigo, A. de, Hammer, F., Hartmann, D.H., Jakobsson, P., Kouveliotou, C., Laskar, T., Levan, A.J., and Rossi, A

Abstract

Contains fulltext : 221960.pdf (publisher's version ) (Open Access)

Published
2020

12. ALMA and GMRT Constraints on the Off-axis Gamma-Ray Burst 170817A from the Binary Neutron Star Merger GW170817

Author

Kim, S., primary, Schulze, S., additional, Resmi, L., additional, González-López, J., additional, Higgins, A. B., additional, Ishwara-Chandra, C. H., additional, Bauer, F. E., additional, Gregorio-Monsalvo, I. de, additional, Pasquale, M. De, additional, Postigo, A. de Ugarte, additional, Kann, D. A., additional, Martín, S., additional, Oates, S. R., additional, Starling, R. L. C., additional, Tanvir, N. R., additional, Buchner, J., additional, Campana, S., additional, Cano, Z., additional, Covino, S., additional, Fruchter, A. S., additional, Fynbo, J. P. U., additional, Hartmann, D. H., additional, Hjorth, J., additional, Jakobsson, P., additional, Levan, A. J., additional, Malesani, D., additional, Michałowski, M. J., additional, Milvang-Jensen, B., additional, Misra, K., additional, O’Brien, P. T., additional, Sánchez-Ramírez, R., additional, Thöne, C. C., additional, Watson, D. J., additional, and Wiersema, K., additional

Published
2017
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15. Spectroscopy of the short-hard GRB 130603B:The host galaxy and environment of a compact object merger

Author

Postigo, A. de Ugarte, Thoene, C. C., Rowlinson, A., Garcia-Benito, R., Levan, A. J., Gorosabel, J., Goldoni, P., Schulze, S., Zafar, T., Wiersema, K., Sanchez-Ramirez, R., Melandri, A., D'Avanzo, P., Oates, S., D'Elia, V., Pasquale, M. De, Kruehler, T., Horst, A. J. van der, Xu, Dong, Watson, D., Piranomonte, S., Vergani, S., Milvang-Jensen, B., Kaper, L., Malesani, D., Fynbo, J. P. U., Cano, Z., Covino, S., Flores, H., Greiss, S., Hammer, F., Hartoog, O. E., Hellmich, S., Heuser, C., Hjorth, J., Jakobsson, P., Mottola, S., Sparre, M., Sollerman, J., Tagliaferri, G., Tanvir, N. R., Vestergaard, Marianne, Wijers, R. A. M. J., Postigo, A. de Ugarte, Thoene, C. C., Rowlinson, A., Garcia-Benito, R., Levan, A. J., Gorosabel, J., Goldoni, P., Schulze, S., Zafar, T., Wiersema, K., Sanchez-Ramirez, R., Melandri, A., D'Avanzo, P., Oates, S., D'Elia, V., Pasquale, M. De, Kruehler, T., Horst, A. J. van der, Xu, Dong, Watson, D., Piranomonte, S., Vergani, S., Milvang-Jensen, B., Kaper, L., Malesani, D., Fynbo, J. P. U., Cano, Z., Covino, S., Flores, H., Greiss, S., Hammer, F., Hartoog, O. E., Hellmich, S., Heuser, C., Hjorth, J., Jakobsson, P., Mottola, S., Sparre, M., Sollerman, J., Tagliaferri, G., Tanvir, N. R., Vestergaard, Marianne, and Wijers, R. A. M. J.

Abstract

Short duration gamma-ray bursts (SGRBs) are thought to be related to the violent merger of compact objects, such as neutron stars or black holes, which makes them promising sources of gravitational waves. The detection of a 'kilonova'-like signature associated to the Swift-detected GRB 130603B has suggested that this event is the result of a compact object merger. Our knowledge on SGRB has been, until now, mostly based on the absence of supernova signatures and the analysis of the host galaxies to which they cannot always be securely associated. Further progress has been significantly hampered by the faintness and rapid fading of their optical counterparts (afterglows), which has so far precluded spectroscopy of such events. Afterglow spectroscopy is the key tool to firmly determine the distance at which the burst was produced, crucial to understand its physics, and study its local environment. Here we present the first spectra of a prototypical SGRB afterglow in which both absorption and emission features are clearly detected. Together with multiwavelength photometry we study the host and environment of GRB 130603B. From these spectra we determine the redshift of the burst to be z = 0.3565+/-0.0002, measure rich dynamics both in absorption and emission, and a substantial line of sight extinction of A_V = 0.86+/-0.15 mag. The GRB was located at the edge of a disrupted arm of a moderately star forming galaxy with near-solar metallicity. Unlike for most long GRBs (LGRBs), N_HX / A_V is consistent with the Galactic ratio, indicating that the explosion site differs from those found in LGRBs. The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the compact object binary.

Published
2014

16. THE ULTRA-LONG GRB 111209A. II. PROMPT TO AFTERGLOW AND AFTERGLOW PROPERTIES.

Author

Stratta, G., Gendre, B., Atteia, J. L., Boër, M., Coward, D. M., Pasquale, M. De, Howell, E., Klotz, A., Oates, S., and Piro, L.

Subjects
GAMMA ray bursts, AFTERGLOW (Physics), RADIO telescopes, STARBURSTS, SUPERNOVAE
Abstract

The “ultra-long” gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ∼4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of AV = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ∼1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor. [ABSTRACT FROM AUTHOR]

Published
2013
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19. Anatomy of a dark burst – the afterglow of GRB 060108.

Author

Oates, S. R., Mundell, C. G., Piranomonte, S., Page, K. L., Pasquale, M. De, Monfardini, A., Melandri, A., Zane, S., Guidorzi, C., Malesani, D., Gomboc, A., Bannister, N., Blustin, A. J., Capalbi, M., Carter, D., D'Avanzo, P., Kobayashi, S., Krimm, H. A., O'Brien, P. T., and Page, M. J.

Subjects
GAMMA ray bursts, AFTERGLOW (Physics), X-ray telescopes, LIGHT curves, GAMMA rays, ASTRONOMICAL spectroscopy
Abstract

We present a multiwavelength study of GRB 060108 – the 100th gamma-ray burst discovered by Swift. The X-ray flux and light curve (three segments plus a flare) detected with the X-ray Telescope are typical of Swift long bursts. We report the discovery of a faint optical afterglow detected in deep BVRi′-band imaging obtained with the Faulkes Telescope North beginning 2.75 min after the burst. The afterglow is below the detection limit of the Ultraviolet/Optical Telescope within 100 s of the burst, while is evident in K-band images taken with the United Kingdom Infrared Telescope 45 min after the burst. The optical light curve is sparsely sampled. Observations taken in the R and i′ bands can be fitted either with a single power-law decay in flux, where , or with a two-segment light curve with an initial steep decay , flattening to a slope . A marginal evidence for rebrightening is seen in the i′ band. Deep R-band imaging obtained ∼12 d post-burst with the Very Large Telescope reveals a faint, extended object at the location of the afterglow. Although the brightness is compatible with the extrapolation of the slow decay with index α2, significant flux is likely due to a host galaxy. This implies that the optical light curve had a break before 12 d, akin to what observed in the X-rays. We derive the maximum photometric redshift for GRB 060108. We find that the spectral energy distribution at 1000 s after the burst, from the optical to the X-ray range, is best fitted by a simple power law, , with and a small amount of extinction. The optical to X-ray spectral index confirms GRB 060108 to be one of the optically darkest bursts detected. Our observations rule out a high redshift as the reason for the optical faintness of GRB 060108. We conclude that a more likely explanation is a combination of an intrinsic optical faintness of the burst, a hard optical to X-ray spectrum and a moderate amount of extinction in the host galaxy. [ABSTRACT FROM AUTHOR]

Published
2006
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