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 the DARTH FADER algorithm, a new wavelet-based method forestimating redshifts of galaxy spectra in spectral surveys that is particularlyadept in the very low SNR regime. We use a standard cross-correlation method toestimate the redshifts of galaxies, using a template set built using a PCAanalysis on a set of simulated, noise-free spectra. Darth Fader employs waveletfiltering to both estimate the continuum & to extract prominent line featuresin each galaxy spectrum. A simple selection criterion based on the number offeatures present in the spectrum is then used to clean the catalogue: galaxieswith fewer than six total features are removed as we are unlikely to obtain areliable redshift estimate. Applying our wavelet-based cleaning algorithm to asimulated testing set, we successfully build a clean catalogue includingextremely low signal-to-noise data (SNR=2.0), for which we are able to obtain a5.1% catastrophic failure rate in the redshift estimates (compared with 34.5%prior to cleaning). We also show that for a catalogue with uniformly mixed SNRsbetween 1.0 & 20.0, with realistic pixel-dependent noise, it is possible toobtain redshifts with a catastrophic failure rate of 3.3% after cleaning (ascompared to 22.7% before cleaning). Whilst we do not test this algorithmexhaustively on real data, we present a proof of concept of the applicabilityof this method to real data, showing that the wavelet filtering techniquesperform well when applied to some typical spectra from the SDSS archive. TheDarth Fader algorithm provides a robust method for extracting spectral featuresfrom very noisy spectra. The resulting clean catalogue gives an extremely lowrate of catastrophic failures, even when the spectra have a very low SNR. Forvery large sky surveys, this technique may offer a significant boost in thenumber of faint galaxies with accurately determined redshifts.

Darth Fader: Using wavelets to obtain accurate redshifts of spectra at very low signal-to-noise