The first look at Narrow-Line Seyfert 1 Galaxies with eROSITA

Abstract

We present the first look at the spectral and timing analysis of Narrow-Line Seyfert 1 Galaxies (NLS1s) with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spectrum-Roentgen-Gamma (SRG) mission. The sample of about 1,200 NLS1s was obtained via cross-match of the first eROSITA All-Sky Survey (eRASS1) catalogue with the catalogue of spectroscopically selected NLS1s from the Sloan Digital Sky Survey (SDSS) DR12 by Rakshit et al. [ApJS, 229, 39 (2017)]. The X-ray spectral analysis is based on a simple power-law fit. The photon index distribution has a mean value of about 2.81+-0.03, as expected from previous X-ray studies of NLS1s. Interestingly, it is positively skewed, and about 10 percent of the sources are located in the super-soft tail of photon indices larger than 4. These sources are of further interest as their source counts run into the X-ray background at values at around 1 keV. We argue that ionised outflows have been detected by eROSITA and may account for some of the extreme spectral steepness, which is supported by correlations found between the photon index and optical outflows parameters. We analysed the intrinsic X-ray variability of the eRASS1 to eRASS3 light curves of the sample but do not find significant variability neither during the individual survey scans nor between them.

11 pages, 10 figures, accepted for publication in Section 4. Extragalactic astronomy of Astronomy and Astrophysics

References in corpus (15)

• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• The eROSITA X-ray telescope on SRG
• Second ROSAT all-sky survey (2RXS) source catalogue
• Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy
• The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue
• The black hole mass - stellar velocity dispersion relation of narrow-line Seyfert 1 galaxies
• Spectral properties of quasars from Sloan Digital Sky Survey data release 14: The catalog
• A Compton-thick Wind in the High Luminosity Quasar, PDS 456
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The AGN Catalogue and its X-ray Spectral Properties
• A Large, Uniform Sample of X-ray Emitting AGN from the ROSAT All-Sky and Sloan Digital Sky Surveys: the Data Release 5 Sample
• The nature of the extreme X-ray variability in the NLS1 1H 0707-495
• Exploring the Diversity of Type 1 Active Galactic Nuclei Identified in SDSS-IV/SPIDERS
• A comparison of X-ray photon indices among the narrow and broad-line Seyfert 1 galaxies
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The variability catalogue and multi-epoch comparison
• A comparative study of the physical properties for a representative sample of Narrow and Broad-line Seyfert galaxies

Cited by in corpus (3)

• Mildly Super-Eddington Accretion Onto Slowly-Spinning Black Holes Explains the X-Ray Weakness of the Little Red Dots
• Discovery of two promising isolated neutron star candidates in the SRG/eROSITA All-Sky Survey
• Rapid onset of a Comptonisation zone in the repeating tidal disruption event XMMSL2 J140446.9-251135