ALMA [N ii] 205 μ m Imaging Spectroscopy of the Interacting Galaxy System BRI 1202-0725 at Redshift 4.7
- National Astronomical Observatories, Chinese Academy of Sciences (CAS), Beijing 100012 (China)
- Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)
- Nucleo de Astronomia de la Facultad de Ingenieria, Universidad Diego Portales, Av. Ejercito Libertador 441, Santiago (Chile)
- Department of Physics, University of Crete, GR-71003 Heraklion (Greece)
- Purple Mountain Observatory, CAS, Nanjing 210008 (China)
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
- Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción (Chile)
- Centre de Recherche Astrophysique de Lyon (CRAL), Observatoire de Lyon, CNRS, UMR5574, F-69230, Saint-Genis-Laval (France)
- Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)
We present the results from Atacama Large Millimeter/submillimeter Array imaging in the [N ii] 205 μ m fine-structure line (hereafter [N ii]) and the underlying continuum of BRI 1202-0725, an interacting galaxy system at z = 4.7, consisting of a quasi-stellar object (QSO), a submillimeter galaxy (SMG), and two Ly α emitters, all within ∼25 kpc of the QSO. We detect the QSO and SMG in both [N ii] and continuum. At the ∼1″ (or 6.6 kpc) resolution, both the QSO and SMG are resolved in [N ii], with the de-convolved major axes of ∼9 and ∼14 kpc, respectively. In contrast, their continuum emissions are much more compact and unresolved even at an enhanced resolution of ∼0.″7. The ratio of the [N ii] flux to the existing CO(7−6) flux is used to constrain the dust temperature ( T {sub dust}) for a more accurate determination of the FIR luminosity L {sub FIR}. Our best estimated T {sub dust} equals 43 (±2) K for both galaxies (assuming an emissivity index β = 1.8). The resulting L {sub CO(7−6)}/ L {sub FIR} ratios are statistically consistent with that of local luminous infrared galaxies, confirming that L {sub CO(7−6)} traces the star formation (SF) rate (SFR) in these galaxies. We estimate that the ongoing SF of the QSO (SMG) has an SFR of 5.1 (6.9) × 10{sup 3} M {sub ⊙} yr{sup −1} (±30%) assuming Chabrier initial mass function, takes place within a diameter (at half maximum) of 1.3 (1.5) kpc, and will consume the existing 5 (5) × 10{sup 11} M {sub ⊙} of molecular gas in 10 (7) × 10{sup 7} years.
- OSTI ID:
- 22654453
- Journal Information:
- Astrophysical Journal Letters, Vol. 842, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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