The optical emission line spectrum of Mark 110

Abstract

Aims. We analyse in detail the rich emission line spectrum of Mark 110 to determine the physical conditions in the nucleus of this object, a peculiar NLS1 without any detectable Fe II emission associated with the broad line region and with a λ5007/Hβ line ratio unusually large for a NLS1. Methods. We use 24 spectra obtained with the Marcario Low Resolution Spectrograph attached at the prime focus of the 9.2 m HobbyEberly telescope at the McDonald observatory. We fitted the spectrum by identifying all the emission lines (about 220) detected in the wavelength range 4200−6900 Å (at rest). Results. The narrow emission lines are probably produced in a region with a density gradient in the range 10 3 −10 6 cm −3 with a rather high column density (5 × 10 21 cm −2 ). In addition to a narrow line system, three major broad line systems with different line velocity and width are required. We confirm the absence of broad Fe II emission lines. We speculate that Mark 110 is in fact a BLS1 with relatively "narrow" broad lines but with a BH mass large enough compared to its luminosity to have a lower than Eddington luminosity.

Variable oxygen emission from the accretion disk of Mrk 110

“…4. This is consistent with the short timescale delays (τ = 4 ± 2 days) seen for the He ii line, while the broadest (FWHM of 6000 km s −1 ) component of He ii also shows pronounced variability by up to a factor of eight in flux (Véron-Cetty et al 2007). The O vii behaviour may be an extension of this, but from where this higher excitation line originates closer to the black hole in a face-on system.…”

“…Its has no intrinsic X-ray absorption and displays a prominent soft X-ray excess below 2 keV, with a strong, broadened O vii emission line (Boller et al 2007). However, Mrk 110 has an unusually large [O III]λ5007/Hβ ratio and very weak Fe II emission, which is more consistent with broad line Seyfert 1s (BLS1s) rather than NLS1s (Véron-Cetty et al 2007) and indicates a low Eddington ratio (Boroson & Green 1992;Grupe 2004;Véron-Cetty et al 2007). Another peculiar characteristic of Mrk 110 is that it has a rather large black hole mass, as deduced from the detection of gravitational redshifted emission in the variable components of the broad optical lines, with a mean value of M grav = 14 ± 3 × 10 7 M (Kollatschny 2003).…”

The surprising Crab pulsar and its nebula: a review

“…Interestingly however, the spectrum in the inner region of the nebula is rather uniform. The torus, the jet and the small scale structures mentioned in the previous paragraph show no strong spectral variations among them from infrared to X-ray energies (Veron-Cetty & Woltjer 1993, Willingale et al 2001, Temim et al 2006, Mori et al 2004, Tziamtzis et al 2009). At radio frequencies the picture is more complex.…”

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

“…The bright bare AGN Mrk 110 (z = 0.035291) has been classified as a narrow-line Seyfert 1 (NLS1) due to the relatively narrow optical emission lines (<2000 km s −1 FWHM) emitted by its broad-line region (BLR; Osterbrock & Pogge 1985;Goodrich 1989). However, two much broader and more redshifted line components are also observed (∼5000−6000 km s −1 and ∼3340 km s −1 ; Bischoff & Kollatschny 1999;Véron-Cetty et al 2007). In addition, and contrary to NLS1s, Mrk 110 displays an unusually large [O iii]λ5007/Hβ ratio and very weak Fe ii emission, which is more consistent with a broad-line Seyfert 1 (BLS1) and indicates a low Eddington ratio (Boroson & Green 1992;Grupe 2004;Véron-Cetty et al 2007).…”

“…However, two much broader and more redshifted line components are also observed (∼5000−6000 km s −1 and ∼3340 km s −1 ; Bischoff & Kollatschny 1999;Véron-Cetty et al 2007). In addition, and contrary to NLS1s, Mrk 110 displays an unusually large [O iii]λ5007/Hβ ratio and very weak Fe ii emission, which is more consistent with a broad-line Seyfert 1 (BLS1) and indicates a low Eddington ratio (Boroson & Green 1992;Grupe 2004;Véron-Cetty et al 2007). Its X-ray photon index, soft X-ray excess strength, and X-ray variability are similar to that found for BLS1s (Porquet et al 2004;Boller et al 2007;Piconcelli et al 2005;Zhou & Zhang 2010;Ponti et al 2012;Gliozzi & Williams 2020).…”