Optical spectroscopic classification of 35 hard X-ray sources from the Swift-BAT 70-month catalogue
arXiv:2007.12609 · doi:10.1007/s10509-019-3642-9
Abstract
The nature of a substantial percentage (about one fifth) of hard X-ray sources discovered with the BAT instrument onboard the Neil Gehrels Swift Observatory (hereafter Swift) is unknown because of the lack of an identified longer-wavelength counterpart. Without such follow-up, an X-ray catalogue is of limited astrophysical value: we therefore embarked, since 2009, on a long-term project to uncover the optical properties of sources identified by Swift by using a large suite of ground-based telescopes and instruments. In this work, we continue our programme of characterization of unidentified or poorly studied hard X-ray sources by presenting the results of an optical spectroscopic campaign aimed at pinpointing and classifying the optical counterparts of 35 hard X-ray sources taken from the 70-month BAT catalogue. (...) With the use of optical spectra taken at six different telescopes we were able to identify the main spectral characteristics (continuum type, redshift, and emission or absorption lines) of the observed objects, and determined their nature. We identify and characterize a total of 41 optical candidate counterparts corresponding to 35 hard X-ray sources given that, because of positional uncertainties, multiple lower energy counterparts can sometimes be associated with higher energy detections. We discuss which ones are the actual (or at least most likely) counterparts based on our observational results. In particular, 31 sources in our sample are active galactic nuclei: 16 are classified as Type 1 (with broad and narrow emission lines) and 13 are classified as Type 2 (with narrow emission lines only); two more are BL Lac-type objects. We also identify one LINER, one starburst, and 3 elliptical galaxies. The remaining 5 objects are galactic sources: we identify 4 of them as cataclysmic variables, whereas one is a low mass X-ray binary.
Last draft version before referee's approval. Closest to the final published article
References in corpus (19)
- A Radio Pulsar/X-ray Binary Link
- BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
- On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies
- The 5th edition of the Roma-BZCAT. A short presentation
- A Comprehensive Study of 2 000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey: I. The Sample
- BAT AGN Spectroscopic Survey I: Spectral Measurements, Derived Quantities, and AGN Demographics
- The Molonglo Galactic Plane Survey (MGPS-2): Compact Source Catalogue
- Unveiling supergiant fast X-ray transient sources with INTEGRAL
- Seyfert galaxies in the local Universe (z 0.1): the average X-ray spectrum as seen by
- The WISE Blazar-Like Radio-Loud Sources: An All-Sky Catalog Of Candidate Gamma-Ray Blazars
- Distribution of High-Mass X-ray Binaries in the Milky Way
- Indecent Exposure in Seyfert 2 Galaxies: A Close Look
- The merger fraction of active and inactive galaxies in the local Universe through an improved non-parametric classification
- The Sedentary Survey of Extreme High Energy Peaked BL Lacs III. Results from Optical Spectroscopy
- Extinction and metal column density of HI regions up to redshift z~2
- Dwarf nova-type cataclysmic variable stars are significant radio emitters
- A new gamma-ray loud, eclipsing low-mass X-ray binary
- The AGN nature of 11 out of 12 Swift/RXTE unidentified sources through optical and X-ray spectroscopy
- Discovery of Dramatic Optical Variability in SDSS J1100+4421: A Peculiar Radio-Loud Narrow-Line Seyfert 1 Galaxy?