Report
An extremely metal poor star complex in the reionization era: Approaching Population III stars with JWST
| العنوان: | An extremely metal poor star complex in the reionization era: Approaching Population III stars with JWST |
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| المؤلفون: | Vanzella, E., Loiacono, F., Bergamini, P., Mestric, U., Castellano, M., Rosati, P., Meneghetti, M., Grillo, C., Calura, F., Mignoli, M., Bradac, M., Adamo, A., Rihtarsic, G., Dickinson, M., Gronke, M., Zanella, A., Annibali, F., Willott, C., Messa, M., Sani, E., Acebron, A., Bolamperti, A., Comastri, A., Gilli, R., Caputi, K. I., Ricotti, M., Gruppioni, C., Ravindranath, S., Mercurio, A., Strait, V., Martis, N., Pascale, R., Caminha, G. B., Annunziatella, M. |
| المصدر: | A&A 678, A173 (2023) |
| سنة النشر: | 2023 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | We present JWST/NIRSpec integral field spectroscopy (IFS) of a lensed Population III candidate stellar complex (dubbed Lensed And Pristine 1, LAP1), with a lensing-corrected stellar mass ~<10^4 Msun, absolute luminosity M_UV > -11.2 (m_UV > 35.6), confirmed at redshift 6.639 +/- 0.004. The system is strongly amplified (\mu >~ 100) by straddling a critical line of the Hubble Frontier Field galaxy cluster MACS J0416. Despite the stellar continuum is currently not detected in the Hubble and JWST/NIRCam and NIRISS imaging, arclet-like shapes of Lyman and Balmer lines, Lya, Hg, Hb and Ha are detected with NIRSpec IFS with signal-to-noise ratios SNR=5-13 and large equivalent widths (>300-2000A), along with a remarkably weak [OIII]4959-5007 at SNR ~ 4. LAP1 shows a large ionizing photon production efficiency, log(\xi_{ion}[erg~Hz^{-1}])>26. From the metallicity indexes R23 = ([OIII]4959-5007 + [OII]3727) / Hb ~< 0.74 and R3 = ([OIII]5007 / Hb) = 0.55 +/- 0.14, we derive an oxygen abundance 12+log(O/H) ~< 6.3. Intriguingly, the Ha emission is also measured in mirrored sub-components where no [OIII] is detected, providing even more stringent upper limits on the metallicity if in-situ star formation is ongoing in this region (12+log(O/H) < 6, or Z < 0.002 Zsun). The formal stellar mass limit of the sub-components would correspond to ~10^{3} Msun or M_UV fainter than -10. Alternatively, such a metal-free pure line emitting region could be the first case of a fluorescing HI gas region, induced by transverse escaping ionizing radiation from a nearby star-complex. The presence of large equivalent-width hydrogen lines and the deficiency of metal lines in such a small region, make LAP1 the most metal poor star-forming region currently known in the reionization era and a promising site that may host isolated, pristine stars. Comment: 15 pages, 10 figures, 1 table. Submitted to A&A. Comments welcome |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1051/0004-6361/202346981 |
| URL الوصول: | http://arxiv.org/abs/2305.14413 |
| رقم الانضمام: | edsarx.2305.14413 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1051/0004-6361/202346981 |
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