Browsing by Author "Schmidl, S."

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    Four GRB supernovae at redshifts between 0.4 and 0.8
    (2019) Klose, S.; Schmidl, S.; Kann, D. A.; Guelbenzu, A. Nicuesa; Schulze, S.; Greiner, J.; Olivares E, F.; Kruehler, T.; Schady, P.; Afonso, P. M. J.; Filgas, R.; Fynbo, J. P. U.; Rau, A.; Rossi, A.; Takats, K.; Tanga, M.; Updike, A. C.; Varela, K.
    Twenty years ago, GRB 980425/SN 1998bw revealed that long gamma-ray bursts (GRBs) are physically associated with broad-lined type-Ic supernovae (SNe). Since then more than 1000 long GRBs have been localized to high angular precision, but only in similar to 50 cases has the underlying SN component been identified. Using the Gamma-Ray Burst Optical Near-Infrared Detector (GROND) multi-channel imager at ESO/La Silla, during the last ten years we have devoted a substantial amount of observing time to reveal and study SN components in long-GRB afterglows. Here we report on four more GRB SNe (associated with GRBs 071112C, 111228A, 120714B, and 130831A) which were discovered and/or followed-up with GROND and whose redshifts lie between z = 0.4 and 0.8. We study their afterglow light curves, follow the associated SN bumps over several weeks, and characterize their host galaxies. Using SN 1998bw as a template, the derived SN explosion parameters are fully consistent with the corresponding properties of the currently known GRB-SN ensemble, with no evidence for an evolution of their properties as a function of redshift. In two cases (GRB 120714B/SN 2012eb at z = 0.398 and GRB 130831A/SN 2013fu at z = 0.479) additional Very Large Telescope (VLT) spectroscopy of the associated SNe revealed a photospheric expansion velocity at maximum light of about 40 000 and 20 000 km s(-1), respectively. For GRB 120714B, which was an intermediate-luminosity burst, we find additional evidence for a black-body component in the light of the optical transient at early times, similar to what has been detected in some GRB SNe at lower redshifts.
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    Highly luminous supernovae associated with gamma-ray bursts I. GRB 111209A/SN 2011kl in the context of stripped-envelope and superluminous supernovae
    (2019) Kann, D. A.; Schady, P.; Olivares, F. E.; Klose, S.; Rossi, A.; Perley, D. A.; Kruehler, T.; Greiner, J.; Guelbenzu, A. Nicuesa; Elliott, J.; Knust, F.; Filgas, R.; Pian, E.; Mazzali, P.; Fynbo, J. P. U.; Leloudas, G.; Afonso, P. M. J.; Delvaux, C.; Graham, J. F.; Rau, A.; Schmidl, S.; Schulze, S.; Tanga, M.; Updike, A. C.; Varela, K.
    Context. GRB 111209A, one of the longest gamma-ray bursts (GRBs) ever observed, is linked to SN 2011kl, which is the most luminous GRB supernova (SN) detected so far. Several lines of evidence indicate that this GRB-SN is powered by a magnetar central engine.
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    Identifying the host galaxy of the short GRB 100628A
    (EDP SCIENCES S A, 2015) Guelbenzu, A. Nicuesa; Klose, S.; Palazzi, E.; Greiner, J.; Michalowski, M. J.; Kann, D. A.; Hunt, L. K.; Malesani, D.; Rossi, A.; Savaglio, S.; Schulze, S.; Xu, D.; Afonso, P. M. J.; Elliott, J.; Ferrero, P.; Filgas, R.; Hartmann, D. H.; Kruehler, T.; Knust, F.; Masetti, N.; Olivares E, F.; Rau, A.; Schady, P.; Schmidl, S.; Tanga, M.; Updike, A. C.; Varela, K.
    We report on the results of a comprehensive observing campaign to reveal the host galaxy of the short GRB 100628A. This burst was followed by a faint X-ray afterglow but no optical counterpart was discovered. However, inside the X-ray error circle a potential host galaxy at a redshift of z = 0.102 was soon reported in the literature. If this system is the host, then GRB 100628A was the cosmologically most nearby unambiguous short burst with a measured redshift so far. We used the multi-colour imager GROND at the ESO/La Silla MPG 2.2 in telescope. ESO/VLT spectroscopy, and deep Australia Telescope Compact Array (ATCA) radio-continuum observations together with publicly available Gemini imaging data to study the putative host and the galaxies in the field of GRB 100628A. We confirm that inside the X-ray error circle the most probable host-galaxy candidate is the morphologically disturbed, interacting galaxy system at z = 0.102. The interacting galaxies are connected by a several kpc long tidal stream, which our VLT/FORS2 spectroscopy reveals strong emission lines of [O II] [O III], H alpha and H beta, characteristic for the class of extreme emission-line galaxies and indicative of ongoing star formation. The latter leaves open the possibility that the ORB progenitor was a member of a young stellar population. However, we indentify a second host-galaxy candidate slightly outside the X-ray error circle. It is a radio-bright, luminous elliptical galaxy at a redshift z = 0.311. With a K-band luminosity of 2 x 10(11) L-circle dot this galaxy resembles the probable giant elliptical host of the first well-localized short burst. GRB 050509B. If this is the host, then the progenitor of GRB 100628A was a member of an old stellar population.
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    Molecular hydrogen in the damped Lyman α system towards GRB 120815A at z=2.36
    (2013) Kruhler, T.; Ledoux, C.; Fynbo, J. P. U.; Vreeswijk, P. M.; Schmidl, S.; Malesani, D.; Christensen, L.; De Cia, A.; Hjorth, J.; Jakobsson, P.; Kann, D. A.; Kaper, L.; Vergani, S. D.; Afonso, P. M. J.; Covino, S.; de Ugarte Postigo, A.; D'Elia, V.; Filgas, R.; Goldoni, P.; Greiner, J.; Hartoog, O. E.; Milvang-Jensen, B.; Nardini, M.; Piranomonte, S.; Rossi, A.; Sanchez-Ramirez, R.; Schady, P.; Schulze, S.; Sudilovsky, V.; Tanvir, N. R.; Tagliaferri, G.; Watson, D. J.; Wiersema, K.; Wijers, R. A. M. J.; Xu, D.
    We present the discovery of molecular hydrogen (H-2), including the presence of vibrationally-excited H-2* in the optical spectrum of the of GRB 120815A at z = 2.36 obtained with X-shooter at the VLT. Simultaneous photometric broad-band data from GROND X-ray observations by SwiftXRT place further constraints on the amount and nature of dust along the sightline. The galactic of GRB 120815A is characterized by a strong DLA with log(N(H I) = cm(-2)) = 21.95 +/- 0.10, prominent H-2 absorption the Lyman-Werner bands (log(N(H-2) = cm(-2)) = 20.54 +/- 0.13) and thus a molecular gas fraction log f(H-2) = 1.14 +/- 0.15. The d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling of fine-structure and stable transitions of Fe II and Ni II to d = 0.5 +/- 0.1 kpc. The DLA metallicity ([Zn = H] = 1.15 +/- 0.12), visual extinction AV less than or similar to 0.15 mag) and dust depletion ([Zn = Fe] = 1.01 +/- 0.10) are intermediate between the values of well-studied, H-2-deficient DLAs observed at high spectral resolution, and the approximately solar metallicity, highly-obscured and H-2-rich GRB 080607 With respect to N(H I), metallicity, as well as dust-extinction and depletion, GRB 120815A is fairly representative of the properties of GRB-DLAs. This demonstrates that molecular hydrogen is present in at least a fraction of the more typical GRB- and H-2 and H-2* are probably more wide-spread among GRB-selected systems than the few examples of previous detections suggest. Because H-2* transitions are located redwards of the Lyman alpha absorption, H-2* opens a second route for positive searches molecular absorption also in GRB afterglows at lower redshifts and observed at lower spectral resolution. Further detections of gas in GRB-DLAs would allow statistical studies, and, coupled with host follow-up and sub-mm spectroscopy, provide insights into the process and conditions of star-formation at high redshift.
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    The optical identification of events with poorly defined locations: the case of the Fermi GBM GRB 140801A
    (OXFORD UNIV PRESS, 2016) Lipunov, V. M.; Gorosabel, J.; Pruzhinskaya, M. V.; de Ugarte Postigo, A.; Pelassa, V.; Tsvetkova, A. E.; Sokolov, I. V.; Kann, D. A.; Xu, Dong; Gorbovskoy, E. S.; Krushinski, V. V.; Kornilov, V. G.; Balanutsa, P. V.; Boronina, S. V.; Budnev, N. M.; Cano, Z.; Castro Tirado, A. J.; Chazov, V. V.; Connaughton, V.; Delvaux, C.; Frederiks, D. D.; Fynbo, J. F. U.; Gabovich, A. V.; Goldstein, A.; Greiner, J.; Gress, O. A.; Ivanov, K. I.; Jakobsson, P.; Klose, S.; Knust, F.; Komarova, V. N.; Konstantinov, E.; Krylov, A. V.; Kuvshinov, D. A.; Kuznetsov, A. S.; Lipunova, G. V.; Moskvitin, A. S.; Pal'shin, V. D.; Pandey, S. B.; Poleshchuk, V. A.; Schmidl, S.; Sergienko, Yu. P.; Sinyakov, E. V.; Schulze, S.; Sokolov, V. V.; Sokolova, T. N.; Sparre, M.; Thoene, C. C.; Tlatov, A. G.; Tyurina, N. V.; Ulanov, M. V.; Yazev, S. A.; Yurkov, V. V.
    We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg(2) 3-sigma error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory that automatically reacts to all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart was discovered solely from its GBM localization. The optical afterglow of GRB 140801A was found by MASTER Global Robotic Net 53 s after receiving the alert, making it the fastest optical detection of a GRB from a GBM error-box. Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m Big Telescope Alt-azimuth of the Special Astrophysical Observatory of the Russian Academy of Sciences reveals a redshift of z = 1.32. We performed optical and near-infrared photometry of GRB 140801A using different telescopes with apertures ranging from 0.4 to 10.4 m. GRB 140801A is a typical burst in many ways. The rest-frame bolometric isotropic energy release and peak energy of the burst are E-iso = 5.54(-0.24)(+0.26) x 10(52) erg and E-p,E- rest similar or equal to 280 keV, respectively, which is consistent with the Amati relation. The absence of a jet break in the optical light curve provides a lower limit on the half-opening angle of the jet theta = 6 degrees.1. The observed E-peak is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis show that GRB 140801A could belong to the class of intermediate duration. The rapid detection of the optical counterpart of GRB 140801A is especially important regarding the upcoming experiments with large coordinate error-box areas.
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    The optical/NIR afterglow of GRB 111209A: Complex yet not unprecedented
    (2018) Kann, D. A.; Schady, P.; Olivares, E. F.; Klose, S.; Rossi, A.; Perley, D. A.; Zhang, B.; Kruehler, T.; Greiner, J.; Guelbenzu, A. Nicuesa; Elliott, J.; Knust, F.; Cano, Z.; Filgas, R.; Pian, E.; Mazzali, P.; Fynbo, J. P. U.; Leloudas, G.; Afonso, P. M. J.; Delvaux, C.; Graham, J. F.; Rau, A.; Schmidl, S.; Schulze, S.; Tanga, M.; Updike, A. C.; Varela, K.