Deep Learning of DESI Mock Spectra to Find Damped Ly\\textbackslashalpha\ Systems. Wang, B., Zou, J., Cai, Z., Prochaska, J. X., Sun, Z., Ding, J., Font-Ribera, A., Gonzalez, A., Herrera-Alcantar, H. K., Irsic, V., Lin, X., Brooks, D., Chabanier, S., de Belsunce, R., Palanque-Delabrouille, N., Tarle, G., & Zhou, Z. arXiv:2201.00827 [astro-ph], January, 2022. arXiv: 2201.00827
Deep Learning of DESI Mock Spectra to Find Damped Ly\\textbackslashalpha\ Systems [link]Paper  abstract   bibtex   
We have updated and applied a convolutional neural network (CNN) machine learning model to discover and characterize damped Ly\${\textbackslash}alpha\$ systems (DLAs) based on Dark Energy Spectroscopic Instrument (DESI) mock spectra. We have optimized the training process and constructed a CNN model that yields a DLA classification accuracy above 99\${\textbackslash}%\$ for spectra which have signal-to-noise (S/N) above 5 per pixel. Classification accuracy is the rate of correct classifications. This accuracy remains above 97\${\textbackslash}%\$ for lower signal-to-noise (S/N) \${\textbackslash}approx1\$ spectra. This CNN model provides estimations for redshift and HI column density with standard deviations of 0.002 and 0.17 dex for spectra with S/N above 3 per pixel. Also, this DLA finder is able to identify overlapping DLAs and sub-DLAs. Further, the impact of different DLA catalogs on the measurement of Baryon Acoustic Oscillation (BAO) is investigated. The cosmological fitting parameter result for BAO has less than \$0.61{\textbackslash}%\$ difference compared to analysis of the mock results with perfect knowledge of DLAs. This difference is lower than the statistical error for the first year estimated from the mock spectra: above \$1.7{\textbackslash}%\$. We also compared the performance of CNN and Gaussian Process (GP) model. Our improved CNN model has moderately 14\${\textbackslash}%\$ higher purity and 7\${\textbackslash}%\$ higher completeness than an older version of GP code, for S/N \${\textgreater}\$ 3. Both codes provide good DLA redshift estimates, but the GP produces a better column density estimate by \$24{\textbackslash}%\$ less standard deviation. A credible DLA catalog for DESI main survey can be provided by combining these two algorithms.
@article{wang_deep_2022,
	title = {Deep {Learning} of {DESI} {Mock} {Spectra} to {Find} {Damped} {Ly}\{{\textbackslash}alpha\} {Systems}},
	url = {http://arxiv.org/abs/2201.00827},
	abstract = {We have updated and applied a convolutional neural network (CNN) machine learning model to discover and characterize damped Ly\${\textbackslash}alpha\$ systems (DLAs) based on Dark Energy Spectroscopic Instrument (DESI) mock spectra. We have optimized the training process and constructed a CNN model that yields a DLA classification accuracy above 99\${\textbackslash}\%\$ for spectra which have signal-to-noise (S/N) above 5 per pixel. Classification accuracy is the rate of correct classifications. This accuracy remains above 97\${\textbackslash}\%\$ for lower signal-to-noise (S/N) \${\textbackslash}approx1\$ spectra. This CNN model provides estimations for redshift and HI column density with standard deviations of 0.002 and 0.17 dex for spectra with S/N above 3 per pixel. Also, this DLA finder is able to identify overlapping DLAs and sub-DLAs. Further, the impact of different DLA catalogs on the measurement of Baryon Acoustic Oscillation (BAO) is investigated. The cosmological fitting parameter result for BAO has less than \$0.61{\textbackslash}\%\$ difference compared to analysis of the mock results with perfect knowledge of DLAs. This difference is lower than the statistical error for the first year estimated from the mock spectra: above \$1.7{\textbackslash}\%\$. We also compared the performance of CNN and Gaussian Process (GP) model. Our improved CNN model has moderately 14\${\textbackslash}\%\$ higher purity and 7\${\textbackslash}\%\$ higher completeness than an older version of GP code, for S/N \${\textgreater}\$ 3. Both codes provide good DLA redshift estimates, but the GP produces a better column density estimate by \$24{\textbackslash}\%\$ less standard deviation. A credible DLA catalog for DESI main survey can be provided by combining these two algorithms.},
	urldate = {2022-01-05},
	journal = {arXiv:2201.00827 [astro-ph]},
	author = {Wang, Ben and Zou, Jiaqi and Cai, Zheng and Prochaska, J. Xavier and Sun, Zechang and Ding, Jiani and Font-Ribera, Andreu and Gonzalez, Alma and Herrera-Alcantar, Hiram K. and Irsic, Vid and Lin, Xiaojing and Brooks, David and Chabanier, Solène and de Belsunce, Roger and Palanque-Delabrouille, Nathalie and Tarle, Gregory and Zhou, Zhimin},
	month = jan,
	year = {2022},
	note = {arXiv: 2201.00827},
	keywords = {Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics},
}

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