scholarly journals The Relationship Between the Emission-Line Spectra and X-Ray/UV Continuum

1997 ◽  
Vol 159 ◽  
pp. 252-253
Author(s):  
Youjun Lu ◽  
Tinggui Wang
Keyword(s):  
Emission Line ◽  
Inverse Correlation ◽  
Baldwin Effect ◽  
Spectral Parameters ◽  
X Ray ◽  
Physical Conditions ◽  
Broad Emission ◽  
The Baldwin Effect ◽  
The Relationship ◽  
The Continuum

According to photoionization calculations, the broad emission-line (BEL) spectrum depends not only on the physical conditions of line-emitting gas, but also on the spectral shape of incident ionizing continuum, especially from the UV to X-ray. Analysis of emission-line spectra and their correlations with the continuum, therefore, provide a way of probing the anisotropy of ionizing continuum on the BLR scale, which is predicted by current models. Previous works have concentrated on explaining the Baldwin effect, an inverse correlation between equivalent width and continuum luminosity. In this contribution, we present the results of an analysis of 75 AGNs which have well-determined soft X-ray spectral parameters from ROSAT and UV line and continuum measurements.

The X-Ray Spectrum of the X-Ray Binary 4U 1728-34, observed with Suzaku

2017 ◽  
Vol 14 (S339) ◽  
pp. 323-326
Author(s):  
Y. Lei ◽  
H. Zhang ◽  
H. Yuan ◽  
Y. Zhang
Keyword(s):  
Emission Line ◽  
Equivalent Width ◽  
Gaussian Component ◽  
Power Law Model ◽  
Disk Model ◽  
X Ray ◽  
Broad Emission ◽  
Energy Plus ◽  
Broad Emission Line ◽  
The Continuum

AbstractThis poster reported our spectroscopy of the neutron-star X-ray binary 4U 1728-34, observed with Suzaku in 2010 October. It is classified as an atoll source. Its continuous X-ray spectrum can be fitted by a combination of a multicolour accretion-disk model for the soft energy, plus a power-law model for the hard energy. A broad emission line at 6–7 keV can be fitted well using a simple Gaussian component with an equivalent width of ∼322 eV. However, for this object the presence of that feature is disputed, even though our results from Suzaku do suggest the presence of a broad Fe emission line that is consistent with results from XMM-Newton. Nevertheless, the parameters of the line (the line centroid and the equivalent width) are a little different, but that could be due to a difference in modelling the continuum.

scholarly journals The X-Ray Nova GRO J0422+32 in Decline and Quiescence

1996 ◽  
Vol 158 ◽  
pp. 399-400
Author(s):  
M. R. Garcia ◽  
P. J. Callanan ◽  
J. E. McClintock ◽  
P. Zhao
Keyword(s):  
Emission Line ◽  
Emission Region ◽  
Dwarf Novae ◽  
X Ray ◽  
First Order ◽  
Band Emission ◽  
Line Region ◽  
Hα Emission ◽  
The Stability ◽  
The Continuum

We have followed the X-ray nova GRO J0422+32, spectroscopically and photometrically, throughout the decline to quiescence.In the final stages of decay (days 430…880 after the outburst, see Callanan et al. (1995) for the epoch 1995), the equivalent width (EW) of the Hα emission increases monotonically and the R magnitude decreases monotonically. This suggests that the flux in the Hα line is constant, while the continuum fades. The Hα flux is the product of the R band flux (F(R), arbitrarily scaled to 100 at R = 19 mag) and the EW, and is shown in the last column of the table below. The Hα flux varies by only ~ 30% while the continuum fades by a factor of eight (from R = 19 mag to R = 21.3 mag). So, to first order, the Hα luminosity is constant in the final stages of decay. While it is generally the case that the emission line EWs in individual dwarf novae also increase during the decay, the exact behavior seen in GRO J0422+32 is not what is seen for dwarf novae (on average). Using the relation between EW[Hβ] and Mv given in figure 6 of Patterson (1984), we would expect a factor of ~ 5 variation in the Hα flux during days 430…880. The stability of the Hα flux implies that somehow the emission line region is ‘disconnected’ from the continuum (R–band) emission region.

scholarly journals X-ray Spectroscopy of the Ultra-soft Transient 4U1543-47

1990 ◽  
Vol 115 ◽  
pp. 205-208
Author(s):  
H. van der Woerd ◽  
N.E. White ◽  
S.M. Kahn
Keyword(s):  
Emission Line ◽  
Compact Object ◽  
Relativistic Effects ◽  
Emission Feature ◽  
Continuum Emission ◽  
X Ray ◽  
Black Hole Candidate ◽  
Transmission Grating ◽  
Cool Plasma ◽  
The Continuum

AbstractThe X-ray transient 4U1543-47 was observed in 1983 by the EXOSAT observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). Two emission line features are resolved. A broad (FWHM ~2.7 keV) line at 5.9 keV is detected in the GSPC, which we interprete as a redshifted and broadened iron Kα line. The Une broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth (τ ≈ 5), or from Doppler and relativistic effects in the vicinity of a compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission line feature at 0.74 keV, which may be an iron L-transition complex. However, we find that such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral Oxygen. The continuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from a very cool plasma (kT = 0.84 keV) with large scattering depth (τ ≈ 27). The continuum spectrum is strikingly similar to that of black hole candidate LMC X-3.

scholarly journals The first high-redshift changing-look quasars

2020 ◽  
Vol 498 (2) ◽  
pp. 2339-2353 ◽  
Author(s):  
Nicholas P Ross ◽  
Matthew J Graham ◽  
Giorgio Calderone ◽  
K E Saavik Ford ◽  
Barry McKernan ◽  
...  
Keyword(s):  
Emission Line ◽  
Rest Frame ◽  
Population Distribution ◽  
High Redshift ◽  
Baldwin Effect ◽  
Change Models ◽  
High Ionization ◽  
Rapid Changes ◽  
First Time ◽  
The Continuum

ABSTRACT We report on three redshift z > 2 quasars with dramatic changes in their C iv emission lines, the first sample of changing-look quasars (CLQs) at high redshift. This is also the first time the changing-look behaviour has been seen in a high-ionization emission line. SDSS J1205+3422, J1638+2827, and J2228 + 2201 show interesting behaviour in their observed optical light curves, and subsequent spectroscopy shows significant changes in the C iv broad emission line, with both line collapse and emergence being displayed on rest-frame time-scales of ∼240–1640 d. These are rapid changes, especially when considering virial black hole mass estimates of MBH > 109M⊙ for all three quasars. Continuum and emission line measurements from the three quasars show changes in the continuum-equivalent width plane with the CLQs seen to be on the edge of the full population distribution, and showing indications of an intrinsic Baldwin effect. We put these observations in context with recent state-change models, and note that even in their observed low-state, the C iv CLQs are generally above ∼5 per cent in Eddington luminosity.

scholarly journals Panchromatic properties of the extreme Fe ii emitter PHL 1092

2020 ◽  
Vol 494 (3) ◽  
pp. 4187-4202
Author(s):  
Murilo Marinello ◽  
Alberto Rodríguez-Ardila ◽  
Paola Marziani ◽  
Aaron Sigut ◽  
Anil Pradhan
Keyword(s):  
Near Infrared ◽  
Flux Ratio ◽  
Physical Conditions ◽  
A Value ◽  
Broad Component ◽  
Broad Emission ◽  
Hydrogen Lines ◽  
Ionization Parameter ◽  
The Continuum

ABSTRACT We present near-infrared spectroscopy of the NLS1 galaxy PHL 1092 (z = 0.394), the strongest Fe ii emitter ever reported, combined with optical and UV data. We modelled the continuum and the broad emission lines using a power-law plus a blackbody function and Lorentzian functions, respectively. The strength of the Fe ii emission was estimated using the latest Fe ii templates in the literature. We re-estimate the ratio between the Fe ii complex centred at 4570 Å and the broad component of H β, R4570, obtaining a value of 2.58, nearly half of that previously reported (R4570 = 6.2), but still placing PHL 1092 among extreme Fe ii emitters. The full width at half-maximum (FWHM) values found for low-ionization lines are very similar (FWHM ∼ 1200 km s−1), but significantly narrower than those of the hydrogen lines (FWHMH β ∼ 1900 km s−1). Our results suggest that the Fe ii emission in PHL 1092 follows the same trend as in normal Fe ii emitters, with Fe ii being formed in the outer portion of the BLR and co-spatial with Ca ii, and O i, while H β is formed closer to the central source. The flux ratio between the UV lines suggests high densities, log(nH) ∼ 13.0 cm−3, and a low ionization parameter, log(U) ∼ −3.5. The flux excess found in the Fe ii bump at 9200 Å after the subtraction of the NIR Fe ii template and its comparison with optical Fe ii emission suggests that the above physical conditions optimize the efficiency of the Ly α-fluorescence process, which was found to be the main excitation mechanism in the Fe ii production. We discuss the role of PHL 1092 in the eigenvector 1 context.

On the Relationship between the Optical Emission‐Line and X‐Ray Luminosities in Seyfert 1 Galaxies

2004 ◽  
Vol 607 (2) ◽  
pp. 794-799 ◽  
Author(s):  
S. B. Kraemer ◽  
I. M. George ◽  
D. M. Crenshaw ◽  
J. R. Gabel
Keyword(s):  
Emission Line ◽  
Optical Emission ◽  
X Ray ◽  
The Relationship

scholarly journals Metal Abundances and Ionization in QSO Broad Emission-Line Regions

1997 ◽  
Vol 159 ◽  
pp. 96-103 ◽  
Author(s):  
F. Hamann ◽  
J.C. Shields ◽  
R. D. Cohen ◽  
V.T. Junkkarinen ◽  
E.M. Burbidge
Keyword(s):  
Big Bang ◽  
Emission Feature ◽  
Host Galaxies ◽  
Baldwin Effect ◽  
Unusual Behavior ◽  
X Ray ◽  
Continuum Source ◽  
Broad Emission ◽  
Solar Abundances ◽  
Metal Abundances

AbstractWe describe two ongoing studies of QSO broad emissionline regions (BELRs). The first employs the N V λ1240/He II λ1640 and N V/C IV λ1549 line ratios as diagnostics of QSO metallicities. Hamann & Ferland and Ferland et al. showed that many observed N V ratios require enhanced N abundances and Z > Z⊙. Here we present new measurements of large line ratios at redshifts z > 4, which indicate super-solar abundances within ~1 Gyr of the Big Bang (for q0 ≈ 0.5). We also note that the N V line is relatively stronger in more luminous QSOs, in contrast to the well-known Baldwin effect in Lyα, C IV, and O VI λ1034. This unusual behavior in N V could be due to a luminosity-metallicity correlation among QSOs that is coupled to a mass-metallicity relation in their host galaxies.Our second study involves Ne VIII λ774 as a probe of highly ionized gas. We show that a broad emission feature near 774 Å is common in QSOs. Photoionization models indicate that Ne VIII is the most likely identification for this feature. The models also indicate that the Ne VIII emitting gas covers > 40% of the continuum source, has a total hydrogen column density of NH > 1022 cm−2 (for solar abundances) and an ionization parameter of U > 5 (for a nominal QSO continuum shape). This gas would be an X-ray “warm73x201D; absorber — with O VII–O VIII bound-free edges — if it lies along our line-of-sight to the X-ray continuum source.

scholarly journals Emission-line kinematics as a probe of the central engine in QSOs

1986 ◽  
Vol 119 ◽  
pp. 331-336
Author(s):  
Amri Wandel
Keyword(s):  
Energy Source ◽  
Emission Line ◽  
Dynamic Models ◽  
Accretion Rate ◽  
Central Mass ◽  
Large Sample ◽  
Physical Conditions ◽  
Central Engine ◽  
Central Energy ◽  
The Continuum

We investigate the constraints on dynamic models for the line-emitting regions in quasars and AGN. The parameters characterising the central energy source (Mass, efficiency, accretion rate) are calculated in terms of the physical conditions in the line emitting gas. In a large sample the central mass (calculated assuming the emission-line clouds are bound) is proportional to the continuum luminosity. We find typical values of L/LE∼10−2±0.5, e∼0.1-l%, and Ṁ/ṀE∼1–10.

scholarly journals An accretion disk laboratory in the Seyfert 1.9 galaxy NGC 2992

2006 ◽  
Vol 2 (S238) ◽  
pp. 123-126
Author(s):  
Tahir Yaqoob ◽  
Kendrah D. Murphy ◽  
Yuichi Terashima
Keyword(s):  
Black Hole ◽  
Emission Line ◽  
Accretion Disk ◽  
Large Amplitude ◽  
Gravitational Energy ◽  
Test Bed ◽  
Central Black Hole ◽  
X Ray ◽  
Order Of Magnitude ◽  
The Continuum

AbstractOver twenty five years of X-ray observations of the Seyfert 1.9 galaxy NGC 2992 show that it is a promising test-bed for severely constraining accretion disk models. The previous interpretation of the historical activity of NGC 2992 in terms of the accretion disk slowly becoming dormant over many years and then ‘re-building’ itself is not supported by new data. A recent year-long monitoring campaign with RXTE showed that the X-ray continuum varied by more than an order of magnitude on a timescale of weeks. During the large-amplitude flares the centroid energy of the Fe K emission-line complex became significantly redshifted, indicating that the violent activity was occurring close to the putative central black hole where gravitational energy shifts can be sufficiently large. For the continuum, the Compton-y parameter remains roughly constant despite the large-amplitude luminosity variability, with (kT) τ ∼ 20–50.

scholarly journals Relativistic accretion disc reflection in AGN X-ray spectra at z = 0.5–4: a study of four Chandra Deep Fields

2020 ◽  
Vol 498 (4) ◽  
pp. 5284-5298
Author(s):  
L Baronchelli ◽  
K Nandra ◽  
J Buchner
Keyword(s):  
Signal To Noise Ratio ◽  
Accretion Disc ◽  
Data Sets ◽  
Baldwin Effect ◽  
Iron Line ◽  
X Ray ◽  
Future Data ◽  
Deep Fields ◽  
The Baldwin Effect ◽  
Best Fit

ABSTRACT We confirm that the spectra are best fit by a model containing two Compton reflection components, one from distant material, and the other displaying relativistic broadening, most likely from the inner accretion disc. The degree of relativistic broadening indicates a preference for high black hole spin, but the reflection is weaker than that expected for a flat disc illuminated by a point source. We investigate the Compton reflection signatures as a function of luminosity, redshift, and obscuration, confirming an X-ray Baldwin effect for both the narrow and broad components of the iron line. Anticorrelations are also seen with redshift and obscuring column density, but are difficult to disentangle from the Baldwin effect. Our methodology is able to extract information from multiple spectra with low signal-to-noise ratio (SN), and can be applied to future data sets such as eROSITA. We show using simulations, however, that it is necessary to apply an appropriate S/N cut to the samples to ensure the spectra add useful information.

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