Cosmic reionization and metal enrichment from quasar spectroscopy

Program leads: Chris Willott (NRC Canada) & P. Jakobsen (DAWN)

Program duration: 33 hours

Cosmic reionization is one of the key frontiers in astrophysics. The reionization process informs on the properties of the ionizing sources in the early epoch of galaxy formation. We propose to carry out ‘blue extended’ F070LP/G140H  and F170LP/G235H R = 2700 NIRSpec spectroscopy of 5 distant quasars at z > 6.5. These spectra will be used to determine the Lyα absorption properties of the IGM, and hence the hydrogen neutral fraction, by making a range of measurements: IGM mean optical depth, Lyα damping wing, peaks and dark gaps, ionized near-zone size. These measurements will be compared to simulations of reionization in order to place constraints on the process such as timescale, topology and properties of ionizing sources. The same observations will also discover many absorption lines of metals such as oxygen, carbon, silicon, etc. in the IGM. These lines will be used to determine chemical abundances, enrichment histories and constrain feedback models. They also offer another method for determining the ionization state of the IGM from the relative excitation levels of different ions.

For these observations the quasar will be placed in one of the NIRSpec fixed slits while MOS observations of objects in its surrounding will be conducted.

Observations and targets:

ULAS J1120+0641 (z=7.09)

#1222

SLIT+MOS observations in G140H/F070LP (3.2h) and G235H/F170LP (1.6h). Spectroscopic follow-up of the observations of this target conducted by S. Lilly.

UHS J0439+1634 (z=6.5, lensed)

#1222

SLIT+MOS observations in G140H/F070LP (0.8h) and G235H/F170LP (0.8h). MOS targets derived from HST imaging.

DELS J0411-0907 (z=6.8)

#1222

SLIT observations in G140H/F070LP (3.2h) and G235H/F170LP (1.6h). If possible, simultaneous pseudo-slitless observations with the MOS mode may be attempted.

Note: the quasar host galaxy will also be observed as part of the GA IFS program.

VDES J0020-3653 (z=6.9)

#1222

SLIT observations in G140H/F070LP (3.2h) and G235H/F170LP (1.6h). If possible, simultaneous pseudo-slitless observations with the MOS mode may be attempted.

Note: the quasar host-galaxy will also be observed as part of the GA IFS program.

ULAS J1342+0928 (z=7.5)

#1219

 SLIT+MOS observations in G140H/F070LP (3.2h) and G235H/F170LP (1.6h). MOS targets derived from HST imaging.