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High-redshift galaxies and low-mass stars

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posted on 2023-06-08, 23:03 authored by Stephen WilkinsStephen Wilkins, Elizabeth R Stanway, Malcolm N Bremer
The sensitivity available to near-infrared surveys has recently allowed us to probe the galaxy population at z ˜ 7 and beyond. The existing Hubble Wide Field Camera 3 (WFC3) and Visible and Infrared Survey Telescope for Astronomy (VISTA) Infrared Camera (VIRCam) instruments allow deep surveys to be undertaken well beyond 1?µm – a capability that will be further extended with the launch and commissioning of the James Webb Space Telescope (JWST). As new regions of parameter space in both colour and depth are probed, new challenges for distant galaxy surveys are identified. In this paper, we present an analysis of the colours of L- and T-dwarf stars in widely used photometric systems. We also consider the implications of the newly identified Y-dwarf population – stars that are still cooler and less massive than T-dwarfs for both the photometric selection and spectroscopic follow-up of faint and distant galaxies. We highlight the dangers of working in the low-signal-to-noise regime, and the potential contamination of existing and future samples. We find that Hubble/WFC3 and VISTA/VIRCam Y-drop selections targeting galaxies at z ~ 7.5 are vulnerable to contamination from T- and Y-class stars. Future observations using JWST, targeting the z ~ 7 galaxy population, are also likely to prove difficult without deep medium-band observations. We demonstrate that single emission line detections in typical low-signal-to-noise spectroscopic observations may also be suspect, due to the unusual spectral characteristics of the cool dwarf star population.

History

Publication status

  • Published

File Version

  • Published version

Journal

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

Publisher

Wiley-Blackwell

Issue

1

Volume

439

Page range

1038-1050

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2015-11-04

First Open Access (FOA) Date

2015-11-04

First Compliant Deposit (FCD) Date

2015-11-04

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