20.500.12556/RUL-176541 Stacking PANCAKEZ: spectroscopic analysis with NIRSpec stacks in the epoch of reionization. Weak interstellar medium absorption and implications for ionizing photon escape at z ∼ 7 We present a spectral stacking analysis of galaxies at $z \geqslant 6$ observed with the James Webb Space Telescope (JWST). We curate a sample of 64 galaxies spanning redshifts $z_{\mathrm{spec}} = 6.0-9.4$, which have NIRSpec medium-resolution data. The stacks achieve sufficient signal-to-noise ratios to measure equivalent widths (EWs) and velocity centroids ($\nu_{\mathrm{cen}}$) of low-ionization species (LIS) absorption features, transmitted Ly$\alpha$ emission, and nebular emission lines. Overall, we find our sample has weaker LIS absorption lines (EW(LIS) $ \approx$ 1 Å), smaller $\nu_{\mathrm{cen,LIS}}\approx -20 \pm 50$ km s$^{-1}$, and significantly suppressed Ly$\alpha$ (EW(Ly$\alpha$) $\approx 5$ Å), compared to similar studies undertaken at lower redshift. The weaker LIS absorption may suggest a lower covering fraction of H I and larger escape fraction of ionizing photons from our sample. Additionally, the smaller blueshifted $\nu_{\mathrm{cen,LIS}}$ indicates less prevalent or weaker outflows in $z > 6$ galaxies. Stacking our subsample of Ly$\alpha$ emitters (LAEs), we find high EW(H$\beta$) $\approx 170 \pm$ 4 Å and a detection of nebular C IV emission suggesting higher $\xi_{\mathrm{ion}}$ in LAEs at $z > 6$. This work showcases the enormous potential for stacked JWST spectra revealing properties of galaxies and their diffuse interstellar medium in the epoch of reionization. astrophysics galaxies astrofizika galaksije true false true Angleški jezik Slovenski jezik Članek v reviji 2025-12-03 11:55:51 2025-12-03 11:55:52 2025-12-10 03:47:24 0000-00-00 00:00:00 2025 0 0 19 str. no. 2, art. no. 191 Vol. 992 Oct. 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 524.8 1538-4357 10.3847/1538-4357/ae0194 259763971 Glazer_2025_ApJ_992_191.pdf Glazer_2025_ApJ_992_191.pdf 1 675C618959BB2395F586407B494BAD62 836e737dc01864059b27c5c03740a73756add289f05f0733db7be5a9934bb143 e707ab74-d03d-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=222933 https://iopscience.iop.org/article/10.3847/1538-4357/ae0194 0 ee406cb6-d03d-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=222934 Fakulteta za matematiko in fiziko 0 0 0