2023 journal article

Compact [CII] emitters around a C iv absorption complex at redshift 5.7

NATURE, 617(7960), 261-+.

Source: Web Of Science
Added: March 25, 2024

The physical conditions of the circumgalactic medium are investigated by means of intervening absorption-line systems in the spectrum of background quasi-stellar objects (QSOs) out to the epoch of cosmic reionization1–4. A correlation between the ionization state of the absorbing gas and the nature of the nearby galaxies has been suggested by the sources detected in either Lyα or [C ii] 158 μm near to, respectively, highly ionized and neutral absorbers5,6. This is also probably linked to the global changes in the incidence of absorption systems of different types and the process of cosmic reionization7–12. Here we report the detection of two [C ii]-emitting galaxies at redshift z ≈ 5.7 that are associated with a complex, high-ionization C iv absorption system. These objects are part of an overdensity of galaxies and have compact sizes (<2.4 kpc) and narrow linewidths (full width at half maximum (FWHM) ≈ 62–64 km s−1). Hydrodynamic simulations predict that similar narrow [C ii] emission may arise from the heating of small (≲3 kpc) clumps of cold neutral medium or a compact photodissociation region13,14. The lack of counterparts in the rest-frame ultraviolet (UV) indicates severe obscuration of the sources that are exciting the [C ii] emission. These results may suggest a connection between the properties of the [C ii] emission, the rare overdensity of galaxies and the unusual high ionization state of the gas in this region. Investigation of the physical conditions of the circumgalactic medium led to detection of two compact [C ii]-emitting galaxies with narrow linewidths at a redshift of 5.7, associated with a complex, high-ionization C iv absorption system.