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The afterglow and host galaxy of GRB 090205: evidence for a Ly- α emitter at z = 4.65

This study presents evidence for a Lyman-α emitter at redshift z=4.65 associated with the afterglow and host galaxy of GRB 090205. The analysis includes X-ray and optical observations, providing insights into the properties of the host galaxy, such as star formation rate, metallicity, and stellar population age.

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The afterglow and host galaxy of GRB 090205: evidence for a Ly- α emitter at z = 4.65

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  1. The afterglow and host galaxy of GRB 090205: evidence for a Ly-α emitter at z = 4.65 Paolo D’Avanzo (INAF-Osservatorio Astronomico di Brera); in collaboration with:

  2. GRB 090205 15-350 keV T90 = 8.8 ± 1.8 s Perri et al. 2009, GCN 8884 Cummings et al. 2009, GCN 8886 0.5-10 keV Perri et al. 2009, GCN 8884 Evans et al. 2009, GCN 8885 Perri & Stratta, 2009, GCN 8891 No UVOT detection @ t-t0 = 92 s Perri et al. 2009, GCN 8884 Landsman & Perri, 2009, GCN 8893

  3. GRB 090205 t-t0 ~ 7 h RAB~ 22.3; IAB~ 20.8 (D’Avanzo et al. 2009;, GCN 8887) F(t) t -α; α ~ 1.4

  4. GRB 090205 t-t0 ~ 7 h RAB~ 22.3; IAB~ 20.8 (D’Avanzo et al. 2009;, GCN 8887) F(t) t -α; α ~ 1.4 z =4.65 (Thoene et al. 2009, GCN 8889; Fugazza et al. 2009, GCN 8892)

  5. GRB 090205 afterglow tb,1 tb,2 complex X-ray AG: brightening at ~T0+1000s and flaring activity α2 ГX,2 F(t) t -α α1 ~ 1.4; α2 ~ -1.7; α3 ~ 1.2; Time resolved X-ray spectroscopy: absorbed power-law with ГX,1~ ГX,2~ ГX,3~ 2.0 Galactic NH ~ 8 x 1020 cm-2 (no evidence for intrinsic absorbtion; NH < 3.5 x 1022 cm-2) α1 ГX,1 α3 ГX,3 X-ray and optical AG explained within the standard FS model with νc,νm < νopt and νX X-ray “brightnening” possibly due to energy injection into the FS by the engine

  6. GRB 090205: classification T90,rf = 1.6s Ch1 = 15-25 keV Ch2 = 25-50 keV Ch3 = 50-100 keV Ch4 = 100-350 keV Lag(Ch2-Ch1): -15 +/- 867 ms Lag(Ch3-Ch2): 648 +/- 1336 ms Lag(Ch3-Ch1): 705 +/- 1326 ms Eγ,iso = (7.86 ± 1.21)x 1051 erg Ep,i = 192 ± 85 keV

  7. GRB 090205: classification T90,rf = 1.6s Ch1 = 15-25 keV Ch2 = 25-50 keV Ch3 = 50-100 keV Ch4 = 100-350 keV Lag(Ch2-Ch1): -15 +/- 867 ms Lag(Ch3-Ch2): 648 +/- 1336 ms Lag(Ch3-Ch1): 705 +/- 1326 ms Eγ,iso = (7.86 ± 1.21)x 1051 erg Ep,i = 192 ± 85 keV (Antonelli et al. 2009) GRB 090205 Consistent with the Ep,i - Eγ,iso correlation (Amati et al. 2008)

  8. GRB 090205: evidence for a LAE (I)

  9. GRB 090205: evidence for a LAE (I) Lyman-α emission line

  10. GRB 090205: evidence for a LAE (II) Lyman-α emission line 0.4” offset with respect to the continuum (3 kpc @ z=4.65) The same offset is found in imaging frames Ly-α emission from the host galaxy Farthest GRB host galaxy spectroscopically confirmed

  11. GRB 090205 host galaxy LLy-α~ 0.6-0.7 L* SFR ~ 4.2 MSun/yr Z ≥ 0.27 ZSun τ < 150 Myr M* < 150 MSun

  12. GRB 090205: conclusions • optical afterglow and host galaxy discovery; redshift determination • complex X-ray AG: brightening at ~T0+1000s and flaring activity • rest frame short duration (1.6s), but likely long, of massive stellar collapse origin • the host galaxy is a LAE @ z = 4.65 • SFR ~ 4.2 MSun/yr • young stellar population (< 150 Myr) • high metallicity (Z ≥ 0.27 ZSun) • farthest GRB HG spectroscopically confirmed • GRBs as one of the most effective way, complementary to surveys, to study the high-z Universe D’Avanzo et al., A&A submitted

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