English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present complimentary techniques to find emission-line targets and measuretheir properties in a semi-automated fashion from grism observations obtainedwith the Advanced Camera for Surveys aboard the Hubble Space Telescope. Thefirst technique is to find all likely sources in a direct image, extract theirspectra and search them for emission lines. The second method is to look foremission-line sources as compact structures in an unsharp masked version of thegrism image. Using these methods we identify 46 emission-line targets in theHubble Deep Field North using a modest (3 orbit) expenditure of HST observingtime. Grism spectroscopy is a powerful tool for efficiently identifyinginteresting low luminosity, moderate redshift emission-line field galaxies. Thesources found here have a median i band flux 1.5 mag fainter than thespectroscopic redshift catalog of Cohen et al. They have redshift z <= 1.42,high equivalent widths (typically EW > 100{\AA}), and are usually less luminousthan the characteristic luminosity at the same redshift. The chief obstacle ininterpreting the results is line identification, since the majority of sourceshave a single emission line and the spectral resolution is low. Photometricredshifts are useful for providing a first guess redshift. However, even at thedepth of the state-of-the-art data used here, photometric errors can result inuncertainties in line identifications, especially for sources with i > ~24.5ABmag. Reliable line identification for the faintest emission-line galaxiesrequires additional ground-based spectroscopy for confirmation. Of particularconcern are the faint high EW [OII] emitters which could represent a stronglyevolving galaxy population if the possibility that they are mis-identifiedlower redshift interlopers can be ruled out. (Slightly abridged)Comment: AJ accepted. 27 pages, 4 tables, 11 figures. Uses emulateapj.cl

Automated Selection and Characterization of Emission-Line Sources in Advanced Camera for Surveys Wide Field Camera Grism Data