تقرير
High-resolution spectroscopy of a young, low-metallicity optically-thin L=0.02L* star-forming galaxy at z=3.12
| العنوان: | High-resolution spectroscopy of a young, low-metallicity optically-thin L=0.02L* star-forming galaxy at z=3.12 |
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| المؤلفون: | Vanzella, E., De Barros, S., Cupani, G., Karman, W., Gronke, M., Balestra, I., Coe, D., Mignoli, M., Brusa, M., Calura, F., Caminha, G. -B., Caputi, K., Castellano, M., Christensen, L., Comastri, A., Cristiani, S., Dijkstra, M., Fontana, A., Giallongo, E., Giavalisco, M., Gilli, R., Grazian, A., Grillo, C., Koekemoer, A., Meneghetti, M., Nonino, M., Pentericci, L., Rosati, P., Schaerer, D., Verhamme, A., Vignali, C., Zamorani, G. |
| سنة النشر: | 2016 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | We present VLT/X-Shooter and MUSE spectroscopy of an faint F814W=28.60+/-0.33 (Muv=-17.0), low mass (~<10^7 Msun) and compact (Reff=62pc) freshly star-forming galaxy at z=3.1169 magnified (16x) by the Hubble Frontier Fields galaxy cluster Abell S1063. Gravitational lensing allows for a significant jump toward low-luminosity regimes, in moderately high resolution spectroscopy (R=lambda/dlambda ~ 3000-7400). We measured CIV1548,1550, HeII1640, OIII]1661,1666, CIII]1907,1909, Hbeta, [OIII]4959,5007, emission lines with FWHM< 50 km/s and (de-lensed) fluxes spanning the interval 1.0x10^-19 - 2.0x10^-18 erg/s/cm2 at S/N=4-30. The double peaked Lya emission with Delta_v(red-blue) = 280(+/-7)km/s and de-lensed fluxes 2.4_(blue)|8.5_(red)x10^-18 erg/s/cm2 (S/N=38_(blue)|110_(red)) indicate a low column density of neutral hydrogen gas consistent with a highly ionized interstellar medium as also inferred from the large [OIII]5007/[OII]3727>10 ratio. We detect CIV1548,1550 resonant doublet in emission, each component with FWHM ~< 45 km/s, and redshifted by +51(+/-10)km/s relative to the systemic redshift. We interpret this as nebular emission tracing an expanding optically-thin interstellar medium. Both CIV1548,1550 and HeII1640 suggest the presence of hot and massive stars (with a possible faint AGN). The ultraviolet slope is remarkably blue, beta =-2.95 +/- 0.20 (F_lambda=lambda^beta), consistent with a dust-free and young ~<20 Myr galaxy. Line ratios suggest an oxygen abundance 12+log(O/H)<7.8. We are witnessing an early episode of star-formation in which a relatively low NHI and negligible dust attenuation might favor a leakage of ionizing radiation. This galaxy currently represents a unique low-luminosity reference object for future studies of the reionization epoch with JWST. Comment: 7 pages, 4 figures and 1 table; ApJL, accepted for publication |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/2041-8205/821/2/L27 |
| URL الوصول: | http://arxiv.org/abs/1603.01616 |
| رقم الأكسشن: | edsarx.1603.01616 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/2041-8205/821/2/L27 |
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