GN-z11-flash in the context of Gamma-Ray Burst Afterglows
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GN-z11-flash in the context of Gamma-Ray Burst Afterglows
D. A. Kann, M. Blazek, A. de Ugarte Postigo,
1, 2 and C. C. Th¨one IAA-CSIC, Glorieta de la Astronom´ıa, s/n, 18008 Granada, Spain DARK, Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, DK-2100 Copenhagen Ø, Denmark
ABSTRACTThe recently discovered rapid transient GN-z11-flash has been suggested to be the prompt-emissionultraviolet flash associated with a gamma-ray burst serendipitously exploding in the ultra-high- z galaxyGN-z11. We here place the flash into the context of the early ultraviolet emission of gamma-ray bursts,and find it is in agreement with the luminosity distribution of these events. Keywords:
High-redshift galaxies (734), Gamma-ray bursts (629)Gamma-Ray Bursts (GRBs) are among the most powerful explosions in the Universe, and their optical emission atvery early times can be dominated by extremely luminous ultraviolet (UV) flashes (Akerlof et al. 1999; Racusin et al.2008; Bloom et al. 2009; Vestrand et al. 2014), which may be directly linked to the higher-energy prompt emission(e.g., Blake et al. 2005; Vestrand et al. 2005). Such prompt flashes are the most luminous UV/optical sources known(Kann et al. 2007; Perley et al. 2011), implying GRBs are detectable across a broad wavelength range up to the higheststudied redshifts (Tanvir et al. 2009; Salvaterra et al. 2009; Cucchiara et al. 2011; Tanvir et al. 2018). This makesthem highly interesting probes of cosmology, and the main target of mission concepts such as the Gamov Explorer(White 2020) and THESEUS (Amati et al. 2018).Recently, Jiang et al. (2020b) reported a spectroscopic redshift for the ultra-high- z candidate galaxy GN-z11 (Oeschet al. 2016), finding it to lie at z = 10 . K -band spectrumcontains a strong signal that is not seen in the previous or the subsequent integration. They exclude atmospheric,terrestrial, and Solar System sources and present evidence that the transient is very likely associated with GN-z11 andtherefore at the same redshift. This implies extreme luminosity, and they therefore argue that GN-z11-flash is mostlikely the prompt flash of a GRB exploding while they were observing the galaxy. It is extremely unlikely that suchan incidence would occur, however, all other explanations J20 present are even more unlikely, mostly significantly so.Assuming GN-z11-flash is indeed associated with the z ≈
11 galaxy, we here compare its luminosity with a largesample of GRB afterglows (Kann et al. 2006, 2010, 2011, Kann et al. 2021a,b, in prep.). J20 report the redshift ( z =10 . β = − . ± . F ν ∝ ν − β ). Following J20, we here assume the emission is synchrotron radiation and this spectral slope canbe extrapolated. We neglect Galactic foreground extinction, as this galaxy is in the GOODS/Hubble Deep Field North,and it is negligible (a few millimag). We use a λ CDM concordance cosmology with H = 72 km/s/Mpc, Ω M = 0 . λ = 0 .
73. J20 report a slit-loss corrected flux density in the K band of 0 . − . . ± . K = 18 . +0 . − . mag (AB system, K = 16 .
59 mag in Vega). From the spectral slope, we find K − R C = 1 .
54 mag (AB; K − R C = − .
15 mag Vega). Using the redshift and spectral slope, we find a magnitudecorrection to z = 1 of dRc = − . +0 . − . mag (the blue spectrum and the large distance partially cancel each otherout) following Kann et al. (2006). In total, this yields R C = 14 . +0 . − . mag at z = 1, Vega system. Following J20,the non-detection in the following spectrum implies a flux density at least ten times fainter, giving us a corresponding R C > . t = T ) with the end ofthe previous spectral integration, this yields logarithmic central points of 14.0 s for the detection and 53.9 s for the Corresponding author: D. A. [email protected] a r X i v : . [ a s t r o - ph . H E ] D ec upper limit, in the z = 1 frame. For these times, the decay slope is α (cid:38) . F ( t ) ∝ t − α ), a reasonable value for earlyGRB flashes.We plot the final result (red) in Fig. 1, highlighting a sample of z > T ; note some are extrapolations),63/70 (90%) are brighter than the upper limit of R C >
17 mag. (cid:4)(cid:13)(cid:1)(cid:8) (cid:4)(cid:13)(cid:1)(cid:7) (cid:4)(cid:13)(cid:1)(cid:6) (cid:3)(cid:2)(cid:3)(cid:4) (cid:3)(cid:2)(cid:4) (cid:4) (cid:4)(cid:3) (cid:4)(cid:3)(cid:3)(cid:5)(cid:10)(cid:5)(cid:9)(cid:5)(cid:8)(cid:5)(cid:7)(cid:5)(cid:6)(cid:5)(cid:5)(cid:5)(cid:4)(cid:5)(cid:3)(cid:4)(cid:12)(cid:4)(cid:11)(cid:4)(cid:10)(cid:4)(cid:9)(cid:4)(cid:8)(cid:4)(cid:7)(cid:4)(cid:6)(cid:4)(cid:5)(cid:4)(cid:4)(cid:4)(cid:3)(cid:12)(cid:11)(cid:10)(cid:9)(cid:8) (cid:3)(cid:4)(cid:2)(cid:10)(cid:4)(cid:5)(cid:11)(cid:3)(cid:4)(cid:2)(cid:7)(cid:4)(cid:3)(cid:12)(cid:3)(cid:2)(cid:2)(cid:10)(cid:2)(cid:7)(cid:11)(cid:2)(cid:9)(cid:2)(cid:10)(cid:3)(cid:5)(cid:2)(cid:10)(cid:2)(cid:6)(cid:4)(cid:5)(cid:3)(cid:6)(cid:2)(cid:7)(cid:3)(cid:7)(cid:11)(cid:3)(cid:5)(cid:2)(cid:8)(cid:2)(cid:8)(cid:11) (cid:4) (cid:15) (cid:16)(cid:16) (cid:9)(cid:7) (cid:18) (cid:9) (cid:8) (cid:1) (cid:5) (cid:7) (cid:1) (cid:13) (cid:6) (cid:10)(cid:14) (cid:12) (cid:18) (cid:19)(cid:8) (cid:9) (cid:1)(cid:12) (cid:14) (cid:1) (cid:18) (cid:11) (cid:9) (cid:1) (cid:2) (cid:1) (cid:3) (cid:1) (cid:2) (cid:1) (cid:17)(cid:20)(cid:17) (cid:18) (cid:9) (cid:13) (cid:18)(cid:1)(cid:2)(cid:8)(cid:6)(cid:21)(cid:17)(cid:1)(cid:6)(cid:10)(cid:18)(cid:9)(cid:16)(cid:1)(cid:7)(cid:19)(cid:16)(cid:17)(cid:18)(cid:1)(cid:12)(cid:14)(cid:1)(cid:18)(cid:11)(cid:9)(cid:1)(cid:15)(cid:7)(cid:17)(cid:9)(cid:16)(cid:20)(cid:9)(cid:16)(cid:1)(cid:10)(cid:16)(cid:6)(cid:13)(cid:9)(cid:1)(cid:12)(cid:14)(cid:1)(cid:18)(cid:11)(cid:9)(cid:1) (cid:1) (cid:1)(cid:5)(cid:1)(cid:4)(cid:1)(cid:17)(cid:21)(cid:17)(cid:18)(cid:9)(cid:13)(cid:3) (cid:2)(cid:7)(cid:2)(cid:10)(cid:2)(cid:6)(cid:13)(cid:14)(cid:1)(cid:20)(cid:3)(cid:3)(cid:1)(cid:16)(cid:18)(cid:15)(cid:19)(cid:17)
Figure 1.
GN-z11-flash (red) compared to a large sample of GRB afterglows shifted to z = 1. We also highlight afterglows ofhigh-redshift GRBs at z >
6. GN-z11-flash is seen to agree with the early luminosity distribution of GRB afterglows.
ACKNOWLEDGMENTSDAK acknowledges support from the Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). MBacknowledges funding associated to a personal t´ecnico de apoyo fellowship (PTA2016-13192-I). AdUP and CCT ac-knowledge support from Ram´on y Cajal fellowships RyC-2012-09975 and RyC-2012-09984.REFERENCES