Blind Line Search System: BLiSS

arXiv (Cornell University)

Abstract

The increasing sensitivity and spectral resolution of current and forthcoming X-ray observatories, including \textit{XRISM} and \textit{NewAthena}, are expected to reveal increasing numbers of weak and blended emission lines, motivating reproducible tools for their systematic identification. Existing workflows often rely on manual inspection or source-specific analysis pipelines, making homogeneous analyses of large datasets difficult. To address this need, we present BLiSS (Blind Line Search System), an open-source Python package for the fast, blind detection and characterization of emission-line candidates in one-dimensional X-ray spectra without requiring a prior physical continuum model. BLiSS is intended as an exploratory analysis tool that complements subsequent physical spectral modelling. The package estimates an empirical baseline directly from the observed spectrum, identifies positive excesses, groups them into candidate regions, and characterizes them with Gaussian models. Candidate reliability is estimated by comparison with synthetic spectra using a Gaussian Mixture Model classifier. Finally, optional routines perform a simultaneous multi-Gaussian fit and associate detected features with compatible atomic transitions. The methodology implemented in BLiSS has already enabled published spectroscopic studies and is presented here as a documented, modular, and publicly available software package. Its performance is demonstrated using \textit{Chandra}/HETGS and \textit{XRISM}/Resolve observations of the high-mass X-ray binary Vela X-1, one of the best-studied X-ray sources. BLiSS recovers the principal emission features reported in previous studies while providing a fast, reproducible, and instrument-independent workflow for exploratory line searches.

Authors 5

1. Luis Abalo Aachen Huygens-Kamerlingh Onnes Laboratory

   Leiden University · Huygens Institute for History and Culture of the Netherlands

   Affiliation as printed

   Huygens-Kamerlingh Onnes Laboratory , Leiden University , Postbus 9504 , Leiden , 2300 RA , , The Netherlands

2. Graciela Sanjurjo-Ferrín

   University of Alicante

   Affiliation as printed

   Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías , Universidad de Alicante , Ap. Correos 99 , Alicante , E-03080 , , Spain

3. J. Planelles-Villalva

   University of Alicante

   Affiliation as printed

   Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías , Universidad de Alicante , Ap. Correos 99 , Alicante , E-03080 , , Spain

4. J. J. Rodes‐Roca

   University of Alicante

   Affiliation as printed

   Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías , Universidad de Alicante , Ap. Correos 99 , Alicante , E-03080 , , Spain

5. José M. Torrejón

   University of Alicante

   Affiliation as printed

   Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías , Universidad de Alicante , Ap. Correos 99 , Alicante , E-03080 , , Spain