Open AccessXMM–Newton first X‐ray detection of the low‐ionization broad absorption line quasar PG 1700+518
Author(s) -
Ballo L.,
Piconcelli E.,
Vignali C.,
Schartel N.
Publication year - 2011
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2011.18883.x
Subject(s) - physics , astrophysics , quasar , ionization , spectral line , absorption (acoustics) , emission spectrum , line (geometry) , photon , absorption spectroscopy , x ray , epic , astronomy , galaxy , ion , optics , art , geometry , mathematics , literature , quantum mechanics
ABSTRACT We report the first high‐energy detection of PG 1700+518, a well‐known low‐ionization broad absorption line quasar (quasi‐stellar object, QSO). Due to previous X‐ray non‐detection, it was classified as soft X‐ray weak QSO. We observed PG 1700+518 with XMM–Newton for about 60 ks divided in three exposures. The spectrum below 2 keV is very steep, Γ∼ 2.4–3.8, while at higher energies the extremely flat emission (photon index Γ∼ 0.15, when modelled with a power law) suggests the presence of strong absorption ( N H, pl ∼ 2 × 10 23 cm −2 , Γ fixed to 1.8) or a reflection‐dominated continuum. The broad‐band flux is consistent with previous non‐detection. Simultaneous European Photon Imaging Camera (EPIC) and Optical Monitor (OM) data confirm its X‐ray weakness ( observed α ox ∼−2.2). The level of obscuration derived from the X‐ray spectra of PG 1700+518 cannot explain its soft X‐ray nuclear weakness unless a column density of N H ≳ 2 × 10 24 cm −2 is present.