From observations carried out with the telescopes BTA/SCORPIO and VLT/UVES and
from data of new catalogs SDSS-III and others, the characteristic signatures of
the clustering of field galaxies with a redshift of z≈0.56
around the gamma-ray burst GRB 021004 position were detected.
1. From data of multiband BVRI photometry of 263 galaxies (16<B<∼28-th st.magn.)
in the BTA field of size ∼4'×4' in direction of this gamma-ray burst (with account for
HST/ACS photometry), the distribution of photometric redshifts shows a peak at z≈0.56.
2. The Mg II2796/2803Å (fig. 2) absorption doublet at a redshift of z=0.56
as detected in the VLT/UVES spectra of GRB 021004 afterglow (with the proper redshift zš=š2.33),
i.e. for galaxy clusters with z≈0.56 being around the line of sight of this gamma-ray burst.
3.The clustering of galaxies was detected in a larger area (∼3×3 sq. degrees)
around GRBš021004 position with the effective peak near z≈0.56 (fig. 3), detectable
from distributions of spectral and photometric z with the use of new catalogs of galaxy clusters
based on data of the Sloan Digital Sky Survey III and also its part, the Baryon Oscillation
4.From data of 6 catalogs (with the depth in r<21.5 st.magn. for photometric and B<23 st.magn. for spectral redshifts z)
the size of the whole inhomogeneity in distribution of galaxy clusters – a supercluster with a peak near
z≈0.56, was estimated as ∼7°±1°.
1) Ilya V. Sokolov, Oskar J.A. Bravo Calle and Yu.V. Baryshev ,
Study of BTA, Hubble, and Spitzer GRB 021004 deep field”, Gamma–ray Bursts: 15 Years of GRB Afterglows – Progenitors, Environments and Host Galaxies from the Nearby
to the Early Universe (A.J. Castro-Tirado, J.Gorosabel and I.H. Park (eds)), EAS Publications Series,
61 (2013) 435-437 (DOI: 10.1051/eas/1361070)
2) Sokolov, Ilya V.; Castro-Tirado, A. J.; Verkhodanov, O. V.; Zhelenkova, O. P.; Baryshev, Yu. V.,
“Clustering of galaxies around the GRB 021004 sight-line at z∼0.5” in “Proceedings of the International
Workshop on Quark Phase Transition in Compact Objects and Multimessenger Astronomy: Neutrino Signals,
Supernovae and Gamma-Ray Bursts”, Russia, Nizhnij Arkhyz (SAO RAS), Terskol (BNO INR RAS),
October, 7 – 14, 2015, pp. 111, Publishing house “Sneg”, Pyatigorsk, 2016.
3) Yu. V. Baryshev, Ilya V. Sokolov, Alex S. Moskvitin et al., “Study of Faint Galaxies in the Field of GRB 021004”,
Astrophysical Bulletin, 65, 311 (2010),
4) Sokolov Ilya V., Zhelenkova Olga P., Solovyev Ilya A., Castro-Tirado Alberto J., and Verkhodanov Oleg V.,
“ The field galaxies clustering in GRB 021004 line of sight and in the larger areas with an effective peak near
z≈0.56.” (submitted in the Astrophysical Bulletin).
Alberto J. Castro-Tirado
Photometric redshift distribution of galaxies with a peak near to z≈0.56 in the BTA GRBš021004 field
(of the size ∼4'×4') estimated from BTA multicolor BVRI photometry (+HST/ACS data) of 277
galaxies in direction of this GRB.
The Mg II 2796/2803Å absorption doublet at z≈0.56 in the GRB 021004 afterglow VLT/UVES spectra obtained
for the afterglow.
The galaxy clustering in a larger (∼3 × sq. degrees) rea around GRB 021004 with an
effective peak near z≈0.56 for spectral and photometric redshift distributions from new catalogs with galaxy clusters.