scholarly journals A Link Between Seyfert Emission-Line Widths and X-Ray Continuum Slopes

1997 ◽  
Vol 159 ◽  
pp. 248-251
Author(s):  
Th. Boile ◽  
W.N. Brandt
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Optical Emission ◽  
Emission Lines ◽  
Narrow Line ◽  
Rapid Variability ◽  
X Ray ◽  
Accretion Rates ◽  
Line Widths ◽  
Almost All

AbstractThis paper reports on AGN with extremely soft X-ray spectra observed with ROSAT. From their optical emission lines, these objects are classified as narrow-line Seyfert 1 galaxies (NLSl), almost all with extremely large Fe II/Hβ flux ratios and relatively narrow optical lines of hydrogen. NLSl have generally steeper soft X-ray continuum slopes than normal Seyfert 1s, and there may exist an anticorrelation between 0.1–2.4 keV continuum slope and the FWHM of the Hβ line. Objects with steep 0.1–2.4 keV continuum slopes and Hβ FWHM > 3000 km s−1 are clearly discriminated against by nature. When simple power-law models are fit to the data, photon indices reach values up to about 5, much higher than is usually seen in Seyfert 1s. Models with smaller-mass black holes and/or higher accretion rates show some promise to explain the relation between the FWHM of the Hβ line and the X-ray continuum slope. We further report evidence for persistent giant and rapid variability in the ultrasoft narrow-line Seyfert 1 galaxy IRAS 13224–3809.

scholarly journals X-ray detected AGN in SDSS dwarf galaxies

2020 ◽  
Vol 492 (2) ◽  
pp. 2268-2284 ◽  
Author(s):  
Keir L Birchall ◽  
M G Watson ◽  
J Aird
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Growth Rates ◽  
Dwarf Galaxies ◽  
Optical Emission ◽  
Host Galaxy ◽  
X Ray ◽  
Wide Range ◽  
Accretion Rates ◽  
Parent Sample

ABSTRACT In this work we present a robust quantification of X-ray selected AGN in local (z ≤ 0.25) dwarf galaxies ($M_\mathrm{*} \le 3 \times 10^9 \, \mathrm{M_\odot }$). We define a parent sample of 4331 dwarf galaxies found within the footprint of both the MPA-JHU galaxy catalogue (based on SDSS DR8) and 3XMM DR7, performed a careful review of the data to remove misidentifications and produced a sample of 61 dwarf galaxies that exhibit nuclear X-ray activity indicative of an AGN. We examine the optical emission line ratios of our X-ray selected sample and find that optical AGN diagnostics fail to identify 85 per cent of the sources. We then calculated the growth rates of the black holes powering our AGN in terms of their specific accretion rates (∝ LX/M*, an approximate tracer of the Eddington ratio). Within our observed sample, we found a wide range of specific accretion rates. After correcting the observed sample for the varying sensitivity of 3XMM, we found further evidence for a wide range of X-ray luminosities and specific accretion rates, described by a power law. Using this corrected AGN sample we also define an AGN fraction describing their relative incidence within the parent sample. We found the AGN fraction increases with host galaxy mass (up to ≈6 per cent) for galaxies with X-ray luminosities between $10^{39} \, $ and $10^{42} \, \mathrm{erg\, s^{-1}}$, and by extrapolating the power law to higher luminosities, we found evidence to suggest the fraction of luminous AGN ($L_\mathrm{X} \ge 10^{42.4} \, \mathrm{erg\, s^{-1}}$) is constant out to z ≈ 0.7.

scholarly journals Ultrasoft Narrow-line Seyfert 1 Galaxies: An Extreme of Accretion onto Supermassive Black Holes

2000 ◽  
Vol 195 ◽  
pp. 207-208
Author(s):  
W. N. Brandt
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
High Mass ◽  
General Context ◽  
Narrow Line ◽  
X Ray ◽  
Basic Properties ◽  
The Future ◽  
Accretion Rates ◽  
New Phenomena

X-ray studies of ultrasoft narrow-line Seyfert 1 galaxies are revealing surprising new phenomena that are expanding our understanding of Seyfert activity, and they may well allow us to observe the effects of high mass accretion rates onto supermassive black holes. I briefly review the basic properties of these galaxies, their importance in a general context, and the prospects for studying them further in the future.

scholarly journals Relativistic Fe Kα line and ensemble spins of black holes in narrow-line Seyfert 1 galaxies

2014 ◽  
Vol 10 (S312) ◽  
pp. 39-42
Author(s):  
Weimin Yuan ◽  
Zhu Liu ◽  
Youjun Lu ◽  
Xin-Lin Zhou
Keyword(s):  
Black Holes ◽  
Seyfert Galaxies ◽  
Emission Feature ◽  
Narrow Line ◽  
Massive Black Holes ◽  
X Ray ◽  
Accretion Rates ◽  
Black Hole Growth ◽  
Average Spin ◽  
Hole Growth

AbstractWhile a broad line of the Fe Kα emission is commonly found in the X-ray spectra of typical Seyfert galaxies, the situation is unclear in the case of Narrow Line Seyfert 1 galaxies (NLS1s)—an extreme subset which are generally thought to harbor less massive black holes with higher accretion rates. We report results of our study of the assemble property of the Fe K line in NLS1s by stacking the X-ray spectra of a large sample of 51 NLS1s observed with XMM-Newton. We find in the stacked X-ray spectra a prominent, broad emission feature over 4–7 keV, which is characteristic of the broad Fe Kα line. Our results suggest that a relativistic broad Fe line may in fact be common in NLS1s. The line profile is used to study the average spin of the black holes in the sample. We find, for the first time, that their black holes are constrained to be likely spinning at averagely low or moderate rates as a population. The implications of the results are discussed in the context of the black hole growth in NLS1 galaxies.

scholarly journals Gamma-ray-emitting narrow-line Seyfert 1 galaxies: the Swift view

2020 ◽  
Vol 496 (2) ◽  
pp. 2213-2229 ◽  
Author(s):  
F D’Ammando
Keyword(s):  
Gamma Ray ◽  
Thermal Emission ◽  
Optical Emission ◽  
X Rays ◽  
Narrow Line ◽  
X Ray ◽  
Relativistic Jet ◽  
Photon Index ◽  
Γ Ray ◽  
Lower Variability

ABSTRACT We report the analysis of all Swift observations available up to 2019 April of γ-ray-emitting narrow-line Seyfert 1 galaxies (NLSy1). The distribution of X-ray luminosities (and fluxes) indicates that the jet radiation significantly contributes to their X-ray emission, with Doppler boosting making values higher than other radio-loud NLSy1. The 0.3–10 keV photon indices are on average harder with respect to radio-quiet and radio-loud NLSy1, confirming a dominant jet contribution in X-rays. However, the lower variability amplitude with respect to blazars and the softening of the spectrum in some periods suggests that also the corona radiation contributes to the X-ray emission. In optical and ultraviolet (UV) significant flux changes have been observed on daily, weekly, and monthly time-scale, providing a clear indication of the significant contribution of the jet radiation in this part of spectrum. A strong correlation between X-ray, UV, and optical emission and simultaneous flux variations have been observed in 1H 0323+342, SBS 0846+513, PMN J0948+0022 as expected in case the jet radiation is the dominant mechanism. Correlated multiband variability favours the jet-dominated scenario also in FBQS J1644+2619 and PKS 2004−447. The summed X-ray Telescope spectra of 1H 0323+342, SBS 0846+513, PMN J0948+0022, and FBQS J1644+2619 are well fitted by a broken power law with a break around 2 keV. The spectrum above 2 keV is dominated by the non-thermal emission from a beamed relativistic jet, as suggested by the hard photon index. A Seyfert-like feature like the soft X-ray excess has been observed below 2 keV, making these γ-ray-emitting NLSy1 different from typical blazars.

scholarly journals Fraction of the X-ray selected AGNs with optical emission lines in galaxy groups

2017 ◽  
Vol 362 (4) ◽  
Author(s):  
Feng Li ◽  
Qirong Yuan ◽  
Weihao Bian ◽  
Xi Chen ◽  
Pengfei Yan
Keyword(s):  
Optical Emission ◽  
Emission Lines ◽  
X Ray ◽  
Galaxy Groups

scholarly journals X-ray time lags from a pivoting power law in black holes

2004 ◽  
Vol 414 (3) ◽  
pp. 795-806 ◽  
Author(s):  
E. Körding ◽  
H. Falcke
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Time Lags ◽  
X Ray

scholarly journals Optical Emission Lines and the X-Ray Properties of Type 1 Seyfert Galaxies

2011 ◽  
Vol 20 (3) ◽  
pp. 442-447
Author(s):  
G. La Mura ◽  
S. Ciroi ◽  
V. Cracco ◽  
D. Ilić ◽  
L. Č. Popović ◽  
...  
Keyword(s):  
Structural Model ◽  
Optical Emission ◽  
Seyfert Galaxies ◽  
Emission Lines ◽  
Line Profiles ◽  
Energy Bands ◽  
X Ray ◽  
Line Region ◽  
Spectral Components

Abstract In this contribution we report on the study of the optical emission lines and X-ray spectra of a sample of Type 1 AGNs, collected from the SDSS database and observed by the XMM-Newton satellite. Using different instruments onboard XMM, we identify the spectral components of the soft and hard energy bands (in the range from 0.3 keV to 10 keV). The properties of the X-ray continuum and of the Fe Kα line feature are related to the optical broad emission line profiles and intensity ratios. The resulting picture of emission, absorption and reflection processes is interpreted by means of a structural model of the broad line region, developed on the basis of independent optical and radio observations.

scholarly journals 4 Years of Radio to X-ray Observations of 3C 273

1989 ◽  
Vol 134 ◽  
pp. 112-113
Author(s):  
T.J.-L. Courvoisier ◽  
E. I. Robson ◽  
A. Blecha ◽  
P. Bouchet
Keyword(s):  
Near Infrared ◽  
Optical Emission ◽  
Light Curves ◽  
Physical Parameters ◽  
List Type ◽  
Type Number ◽  
Rapid Variability ◽  
X Ray ◽  
Model Independent ◽  
Ir Emission

The quasar 3C273 has been repeatedly observed at radio, mm, IR, optical, UV and X-ray frequencies since December 1983. A complex pattern of continuum variations has been discovered, which can be used to provide model independent physical parameters, and to constrain different models. The main features revealed by our set of observations are: (i)A flux decrease by 40% in the 2–10 kev flux in 20 days in early 1984 (Courvoisier et al. 1987).(ii)Differences between the X-ray light curves at 0.5 keV and 2–10 keV.(iii)A drop in the mm to mid-IR emission by factors 2–4 in early 1986, while the near infrared flux remained stable (Robson et al. 1986).(iv)A decrease in the ultraviolet intensity of ∼40% in about 6 months in 1987 (Ulrich, Courvoisier and Wamsteker 1988).(v)Rapid variability in the infrared and optical emission on timescales as short as one day in 1988 (Courvoisier et al. 1988 and Robson, Courvoisier and Bouchet this conference).

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