First [NII] 122 μm line detection in a starburst pair at z = 4.7. Issue Volume 15:Issue S341(2019) (November 2019)

• Record Type: Journal Article
• Authors: Lee, Minju M.; Nagao, Tohru; De Breuck, Carlos
• Editors: Boquien, Médéric; Lusso, Elisabeta; Gruppioni, Carlotta; Tissera, Patricia
• Is Part Of: Proceedings of the International Astronomical Union. Volume 15:Issue S341(2019)
• Page Start: 283
• Page End: 284
• Publication Date: 2019-11
• Subjects: galaxies: evolution, -- galaxies: high-redshift, -- galaxies: ISM, -- galaxies: starburst, -- submillimeter, -- ISM: evolution; Astronomy -- Congresses; Astronomy -- Periodicals; 520
• DOI: 10.1017/S1743921319004782
• Languages: English
• ISSNs: 1743-9213

Abstract

Abstract: We report the first detection of [NII] 122 μ m line toward a QSO-SMG pair, BRI 1202-0725, at z = 4.7 using ALMA. Combining with [NII] 205 μ m line detection and taking the line ratio of [NII]122/[NII]205, we constrain electron densities of both galaxies. The derived electron densities are ${26_{ - 11}^{ + 12}$ and ${134_{ - 39}^{ + 50}$ cm −3 for the SMG and the QSO, respectively, which are the first measurements for galaxies at z > 4. The electron density of the SMG is comparable to the Galactic plane and the average of local spiral galaxies, while the value for the QSO is comparable to local starbursts and optical-line based measurements for star-forming galaxies at z ∼ 2–3. Considering the similar star-formation rates (SFRs) of ≍ 1000 M ⊙ yr −1 for both galaxies, our results suggest a large scatter of electron densities at fixed SFR and caution against using optical lines for dusty starbursts. The details of this report are presented in Lee et al. 2019 (submitted).