分类： 天文学 >> 天文学 提交时间： 2023-02-19
Andrew J. Bunker
Aayush Saxena
Alex J. Cameron
Chris J. Willott
Emma Curtis-Lake
Peter Jakobsen
Stefano Carniani
Renske Smit
Roberto Maiolino
Joris Witstok
Mirko Curti
Francesco D'Eugenio
Gareth C. Jones
Pierre Ferruit
Santiago Arribas
Stephane Charlot
Jacopo Chevallard
Giovanna Giardino
Anna de Graaff
Tobias J. Looser
摘要： We present JADES JWST/NIRSpec spectroscopy of GN-z11, the most luminous candidate $z>10$ Lyman break galaxy in the GOODS-North field with $M_{UV}=-21.5$. We derive a redshift of $z=10.603$ (lower than previous determinations) based on multiple emission lines in our low and medium resolution spectra over $0.8-5.3\,\mu$m. We significantly detect the continuum and measure a blue rest-UV spectral slope of $\beta=-2.4$. Remarkably, we see spatially-extended Lyman-$\alpha$ in emission (despite the highly-neutral IGM expected at this early epoch), offset 555 km/s redward of the systemic redshift. From our measurements of collisionally-excited lines of both low- and high-ionization (including [O II] $\lambda3727$, [Ne III] $\lambda 3869$ and C III] $\lambda1909$) we infer a high ionization parameter ($\log U\sim -2$). We detect the rarely-seen N IV] $\lambda1486$ and N III]$\lambda1748$ lines in both our low and medium resolution spectra, with other high ionization lines seen in low resolution spectrum such as He II (blended with O III]) and C IV (with a possible P-Cygni profile). Based on the observed rest-UV line ratios, we cannot conclusively rule out photoionization from AGN. The high C III]/He II ratios, however, suggest a likely star-formation explanation. If the observed emission lines are powered by star formation, then the strong N III] $\lambda1748$ observed may imply an unusually high $N/O$ abundance. Balmer emission lines (H$\gamma$, H$\delta$) are also detected, and if powered by star formation rather than an AGN we infer a star formation rate of $\sim 20-30 M_{\odot}\,\rm yr^{-1}$ (depending on the IMF) and low dust attenuation. Our NIRSpec spectroscopy confirms that GN-z11 is a remarkable galaxy with extreme properties seen 430 Myr after the Big Bang.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Emma Curtis-Lake
Stefano Carniani
Alex Cameron
Stephane Charlot
Peter Jakobsen
Roberto Maiolino
Andrew Bunker
Joris Witstok
Renske Smit
Jacopo Chevallard
Chris Willott
Pierre Ferruit
Santiago Arribas
Nina Bonaventura
Mirko Curti
Francesco D'Eugenio
Marijn Franx
Giovanna Giardino
Tobias J. Looser
Nora Lützgendorf
摘要： Finding and characterising the first galaxies that illuminated the early
Universe at cosmic dawn is pivotal to understand the physical conditions and
the processes that led to the formation of the first stars. In the first few
months of operations, imaging from the James Webb Space Telescope (JWST) have
been used to identify tens of candidates of galaxies at redshift (z) greater
than 10, less than 450 million years after the Big Bang. However, none of these
candidates has yet been confirmed spectroscopically, leaving open the
possibility that they are actually low-redshift interlopers. Here we present
spectroscopic confirmation and analysis of four galaxies unambiguously detected
at redshift 10.3
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