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I. O ptical identification: GRB host galaxies and massive SFR at intermediate redshifts

The monitoring of GRB afterglows and the study of their host galaxies with the SAO RAS 6-m telescope from 1997 V. Sokolov et al. The review of main results of first optical identifications of gamma-ray bursts (GRBs) under the joint Russian-Spanish observational program.

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I. O ptical identification: GRB host galaxies and massive SFR at intermediate redshifts

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  1. The monitoring of GRB afterglows and the study of their host galaxies with the SAO RAS 6-m telescope from 1997V. Sokolov et al. • The review of main results of first optical identifications of gamma-ray bursts (GRBs) under the joint Russian-Spanishobservational program. • The first resultof the GRB optical identification (with objects already known before): GRBs are identified with ordinary (or the most numerous in the Universe) galaxies up to 28 stellar magnitude and more. The GRB hosts should not be special, but normal field star forming galaxies at comparable redshifts and magnitudes.

  2. I. Optical identification: GRB host galaxiesand massive SFR at intermediate redshifts

  3. Photometric observation of GRB 970508 in SAO RAS Photometry of optical transients Light curves of the optical transient of GRB 970508 in B, V, Rc and Ic bands (Zeiss-1000 and BTA) CCD images of the optical transient of GRB 970508 (Zeiss-1000 and BTA)

  4. Astronomy of GRBs with the 6-m telescope from 1998

  5. A&A, 337, 356 (1998) BVRcIc light curves of GRB970508 optical remnant and colors of underlying host galaxy S.Zharikov, V. Sokolov, and Yu.Baryshev A&A, 372, 438 (2001) Properties of the host galaxy of the gamma-ray burst 970508 and local star-forming galaxies V.Sokolov, S.Zharikov, Yu.Baryshev, M.O. Hanski, K. Nilsson, P. Teerikorpi, L. Nicastro, and E. Palazzi The Rc band field near GRB 970508 optical source. The image size is 33′′ × 33′′. N -top, E-right. The G1, G2, G3 are nearby galaxies. The arrow denotes an optical remnant of GRB970508.

  6. Multi-color photometry and the Rc image of the GRB 980703 host galaxy field from BTA observations in July 1998. The comparison of energy distribution obtained from BVRcIc fluxes (with consideration for the shift in the ultra-violet part of spectrum for z=0.966) of this galaxy with energy distribution in spectra of galaxies of different Hubble types is shown. (The FWHM of each filter for its λeff with consideration for its left shift for z=0.966 are denoted by dotted horizontal segments with bars.) The massive SFR is seen in rest frame UV part spectra of star-forming galaxies. It is just a light of massive stars in the GRB hosts…

  7. A&A 372, 438 (2001), Host galaxies of gamma-raybursts:Spectral energy distributions and internal extinction, V. V. Sokolov, T. A. Fatkhullin, A. J. Castro-Tirado, A. S. Fruchter et al. A comparison of the GRB 970508 host galaxy broadband rest-frame (z = 0.835) flux spectrum with the SED of S5 template galaxies (see Connoly et al. 1995). The flux of the S5 template was scaled to obtain the best fit. Taking into account z, the FWHM of each filter for λeff is marked by dashed horizontal lines with bars.

  8. The population synthesis modeling: Comparison of modeled and observed fluxes in the filters B, V, Rc,Ic, J, H, K for the GRB 980703 host galaxy (z=0.9662). If GRBs are associated with anactive star formation, then we might expect the light oftheir host galaxies to be affected by internal extinction.

  9. A&A 372, 438 (2001) V.Sokolov, T.Fatkhullin, A.J.Castro-Tirado, A.S.Fruchter et al. Host galaxies of gamma-ray bursts: Spectral energy distributions and internal extinction Conclusions: (a) In the case of the host galaxy of GRB 980703 (z=0.9662) theobserved deficit in the B-band can be explained by theexcess of extinction near 2200 A, which is characteristicof the extinction law similar to that of the Milky Way. (b) There is a connection between GRB and H II regions(see Sect. 4, Ahn 2000), and together with the associationof the host galaxy of GRB 990712 with H II galaxies(Vreeswijk et al. 2000b), again implies strong evidence formassive star formation.

  10. z=0.9662

  11. astro-ph/1102.1469, Fig.A.2 from Tayyaba Zafar, Darach Watson, Johan P. U.Fynbo, Daniele Malesani, Páll Jakobsson , and Antonio de UgartePostigo GRB 070802 (z = 2.4541)afterglow were obtainedwith the VLT/FORS2. The 2175Å dust extinctionfeature is clearly seen in the optical spectrum of the afterglow.

  12. A&A, 2001, 372, 438, by V.Sokolov, T.Fatkhullin, A.J.Castro-Tirado, A.S.Fruchter et al. The best fit for the spectral energy distribution (SED) model to the BVRcIcphotometry of the GRB 970508 host galaxy(z=0.8349), assuming theCalzetti extinction law. Also the upper limit ofHST/NICMOS H-band is plotted (Left-hand). Theobservedwavelengths are given.

  13. Bull. Spec. Astrophys. Obs.,2001, 51, 48-50 GRB 970508 host, MBrest = – 18.62 GRB 980703 host, MBrest = – 21.27

  14. Bull. Spec. Astrophys. Obs.,2001, 51, 48-60 and 38-47 (astro-ph/0107399) The observed R-band magnitude vs. spectroscopic redshift forthe first12 GRB host galaxies. The BTAR-band magnitudes (from Sokolov et al, 2001, A&A 372, 438 ) aremarked with circles, while asterisks refer to the resultsof other authors. Also the HDF F606W magnitude vs.photometrical redshift distribution is plotted. Catalogof the F606W magnitudes and photometrical redshiftswas used from Fernández-Soto et al., 1999

  15. A&A 372, 438-455 (2001) Host galaxies of gamma-ray bursts:Spectral energy distributions and internal extinction V. V. Sokolov, T. A. Fatkhullin, A. J. Castro-Tirado, A. S. Fruchter et al. We conclude that long-duration GRBs seem to be closely related to vigorous massive star-forming in their host galaxies. It should be noted that the SFR in the host galaxies is unlikely to be much higher than in galaxies at the same redshifts (z ≳ 1). At this redshift the mean star formation rate is ~20-60 Mʘ / yr. For these reasons we conclude that GRB host galaxies seem to be similar to field galaxies at the same redshift.

  16. It is shown that these galaxiesare usual ones with a highstar formation rate, they are mainly observed in optical bands at redshiftsabout 1 and higher. V. V. Sokolov, T. A. Fatkhullin, A. J. Castro-Tirado, A. S. Fruchter et al., 2001 GRB hosts should not to be special, butnormal, faint, star-forming galaxies (the most abundant),detected at any z just because a GRB eventhas occurred see S.Savaglio et al., 2008

  17. 20012008 Savaglio et al. 2009 ApJ 691, 182 arXiv:0803.2718

  18. II. The optical identification: The direct connection between long-duration GRBs and massive stars, GRBs and puzzles of Core-Collapse Supernovae (CCSNe) … there are multiple long lines of evidence that long-duration (~ 1s-100s) GRBs are associated with death of massive stars, occurring in regions of active star formation embedded in dense clouds of dust and gas.

  19. The review of main results of first optical identifications of gamma-ray bursts (GRBs) under the joint Russian-Spanish observational program. • The first result of the GRB optical identification (with objects already known before): GRBs are identified with ordinary (or the most numerous in the Universe) galaxies up to 28 st. magnitudes and more. The GRB hosts should not be special, but normal field star-forming galaxies at comparable redshifts and magnitudes. • The second result of the GRB identification: now the long-duration GRBs are identified with (may be) ordinary (massive) core-collapse supernovae (CC-SNe, see in the poster report). • So, we have the massive star-forming in GRB hosts and massive star explosions - CCSN/GRB.

  20. The search for differences between nearbySNe identified with GRBs and distant SNe which are to be identified with GRBs can be an additional observational cosmological test. We can ask a question analogous to that on GRB hosts: • do GRB SNe differ from usual (e.g. local) SNe? Generally, what are redshifts at which CC-SNe are quite different from local CC-SNe? • This could be the third important result of the GRB identification.

  21. Thank you. • P.S. See also arXiv: 1111.1406 [astro-ph]

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