X-ray and optical observations of MCG-6-30-15
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Pineda, F. J.↗
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Documentation for the machine-readable version of the Morphological Catalogue of Galaxies (MCG) of Vorontsov-Velyaminov et al, 1962-1968
Modifications, corrections, and the record format are provided for the machine-readable version of the "Morphological Catalogue of Galaxies.' In addition to hundreds of individual corrections, a detailed comparison of the machine-readable with the published catalogue resulted in the addition of 116 missing objects, the deletion of 10 duplicate records, and a format modification to increase storage efficiency.
Warren, W. H., Jr.↗
A Hard Look at Relativistic Reverberation in MCG-5-23-16 and SWIFT J2127.4+5654: Testing the Lamppost Model
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A. Zoghbi↗
Dramatic Changes in the Observed Velocity of the Accretion Disk Wind in MCG-03-58-007 Are Revealed by XMM-Newton and NuSTAR
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V. Braito↗
The stratified disc wind of MCG-03-58-007
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V Braito↗
Uhuru observations of X-ray emission from Seyfert galaxies
A point summation technique has been used to analyze systematically the Uhuru data for X-ray emission from the 88 Seyfert galaxies listed by Weedman (1977), plus MCG 8-11-11 reported by the Ariel 5 group. In addition to measuring the average X-ray intensity for 15 sources reported in the 4U and 2A catalogs, three new candidate sources are found. X-ray variability has previously been reported for NGC 4151, 3C 390.3, and MCG 8-11-11; Mrk 279 is now also found to vary. Furthermore, significant flaring activity from NGC 4151 was observed with as much as a factor of 10 increase in intensity on a time possibly as short as 730 seconds. The local X-ray volume emissivity of Seyfert galaxies is measured, and it is found, with standard assumptions, that from 6% to 25% of the diffuse 2-10-keV X-ray background can be attributed to emission from Seyfert galaxies. The data show that the luminosity function for X-ray Seyferts is rather steep.
Tananbaum, H.↗
Theoretical and Observational Studies of the Central Engines of AGN
In Active Galactic Nuclei (AGN) the luminosity is so intense that the effect of radiation pressure on a particle may exceed the gravitational attraction. It was shown that when such luminosities are reached, relatively cold (not completely ionized) thermal matter clouds may form in the central engines of AGN, where most of the luminosity originates. We show that the spectrum of emission from cold clouds embedded in hot relativistic matter is similar to the observed spectrum. We also show that within the hot relativistic matter, cold matter moves faster than the speed of sound or the Alfven speed, and shocks form. The shocks provide a mechanism by which a localized perturbation can propagate throughout the central engine. The shocked matter can emit the observed luminosity, and can explain the flux and spectral variability. It may also provide an efficient mechanism for the outward transfer of angular momentum and provide the outward flow of winds. With observations from X-ray satellites, emission features from the cold and hot matter may be revealed. Our analysis of X-ray data from the Seyfert 1 galaxy MCG - 6-30-15 over five years using detectors on the Ginga and Rosat satellites, revealed some interesting variable features. A source with hot matter emits non-thermal radiation which is Compton reflected from cold matter and then absorbed by warm (partially ionized) absorbing matter in the first model, which can be fit to the data if both the cold and warm absorbers are near the central engine. An alternative model in which the emission from the hot matter is partially covered by very warm matter (in which all elements except Iron are mostly ionized) is also successful. In this model the cold and warm matter may be at distances of up to 100 times the size of the central engine, well within the region where broad optical lines are produced. The flux variability is more naturally explained by the second model. Our results support the existence of cold matter in, or near, the central engine of MCG -6-30-15. Cold matter in the central engine, and evidence of the effects of shocks, is probably forthcoming with future X-ray satellites.
Sivron, Ran↗
Laboratory Plasma Source as an MHD Model for Astrophysical Jets
The significance of the work described herein lies in the demonstration of Magnetized Coaxial Plasma Gun (MCG) devices like CPS-1 to produce energetic laboratory magneto-flows with embedded magnetic fields that can be used as a simulation tool to study flow interaction dynamic of jet flows, to demonstrate the magnetic acceleration and collimation of flows with primarily toroidal fields, and study cross field transport in turbulent accreting flows. Since plasma produced in MCG devices have magnetic topology and MHD flow regime similarity to stellar and extragalactic jets, we expect that careful investigation of these flows in the laboratory will reveal fundamental physical mechanisms influencing astrophysical flows. Discussion in the next section (sec.2) focuses on recent results describing collimation, leading flow surface interaction layers, and turbulent accretion. The primary objectives for a new three year effort would involve the development and deployment of novel electrostatic, magnetic, and visible plasma diagnostic techniques to measure plasma and flow parameters of the CPS-1 device in the flow chamber downstream of the plasma source to study, (1) mass ejection, morphology, and collimation and stability of energetic outflows, (2) the effects of external magnetization on collimation and stability, (3) the interaction of such flows with background neutral gas, the generation of visible emission in such interaction, and effect of neutral clouds on jet flow dynamics, and (4) the cross magnetic field transport of turbulent accreting flows. The applicability of existing laboratory plasma facilities to the study of stellar and extragalactic plasma should be exploited to elucidate underlying physical mechanisms that cannot be ascertained though astrophysical observation, and provide baseline to a wide variety of proposed models, MHD and otherwise. The work proposed herin represents a continued effort on a novel approach in relating laboratory experiments to astrophysical jet observation. There exists overwhelming similarity among these flows that has already produced some fascinating results and is expected to continue a high pay off in future flow similarity studies.
Mayo, Robert M.↗
Evidence of Spin and Energy Extraction in a Galactic Black Hole Candidate: The XMM-NEWTON/EPIC SPECTRUM of XTE 11650-500
We observed the Galactic black hole candidate XTE J1650-500 early in its fall of 2001 outburst with the XMM-Newton European Photon Imaging pn Camera (EPIC-pn). The observed spectrum is consistent with the source having been in the very high state. We h d a broad, skewed Fe Kar emission line that suggests the primary in this system may be a Kerr black hole and that indicates a steep disk emissivity profile that is hard to explain in terms of a standard accretion disk model. These results are quantitatively and qualitatively similar to those from an XMM-Newton observation of the Seyfert galaxy MCG -6-30-15. The steep emissivity in MCG -6-30-15 may be explained by the extraction and dissipation of rotational energy from a black hole with nearly maximal angular momentum or from material in the plunging region via magnetic connections to the inner accretion disk. If this process is at work in both sources, an exotic but fundamental general relativistic prediction may be confirmed across a factor of l0(exp 6) in black hole mass. We discuss these results in terms of the accretion flow geometry in stellar-mass black holes and the variety of enigmatic phenomena often observed in the very high state.
Miller, J. M.↗
Integral Observations of the Reflection Component of Seyfert Galaxies
The data were analyzed by Dr. Fabian's student Adrian Turner and included in his thesis (completed Sept 2004). We did not detect MCG-6 using the then current software and the spectrum of the Circinus galaxy turned out to be even worse then the published BeppoSAX spectrum. We decided not to do any more work on it. We were contacted about the data in March by Thierry Courvoisier (the data were thea public) as he had a student, Simona Soidi, working on a compilation of spectra. Dr. Fabian sent them the chapter from Adrian's thesis and we provided some general comments on what they were doing on 6 objects. This has since been accepted for publication with Fabian as a co-author. A paper on the Integral AGN catalogue appeared on astro-ph a few days ago which contains an detection of MCG-6 with a very poor spectrum. We didn't detect it because the software back then required a source to be detected within something like 30 min exposure in order to work. Integral is NOT very sensitive.
Fabian, Andrew↗
Observations of Type 1 Seyfert galaxies with the HEAO-1 scanning modulation collimator
Precise positions of four X-ray sources associated with Type 1 Seyfert galaxies are reported which were measured with the HEAO 1 scanning modulation collimator. The Seyferts are confirmed as the X-ray emitters in each case. The sources (and corresponding galaxies) studied include 2A 0551+466 (NGC 4151), 2A 1207+397 (MCG 8-11-11), 2A 1914-589 (ESO 141-G55), and A 1021+198 (NGC 3227). It is found that the X-ray source is located in the nucleus or the nuclear region for NGC 4151 and that the galaxy is unresolved by the present instrument in the other cases.
Griffiths, R. E.↗
HEAO 1 spectra of X-ray emitting Seyfert 1 galaxies
The paper presents the 2-50-keV X-ray spectra and time variability information on seven Seyfert 1 galaxies NGC 3783, NGC 4151, NGC 5548, NGC 6814, MK 509, MCG 8-11-11, and ESO 141-G55, obtained with the A2(2) experiment on HEAO 1. It is concluded that the spectra of Seyfert 1 galaxies can be well represented by flat power laws of high-temperature thermal breamsstrahlung models with relatively low column densities.
Mushotzky, R. F.↗
The C IV 1550 profile in type 1 Seyfert galaxies
The paper presents C IV 1550 A line profiles for the type 1 Seyfert galaxies NGC 5548, Mrk 509, NGC 7469, and MCG-2-58-22. Several line broadening mechanisms and theoretical line profiles are considered, and random motion of discrete clouds is ruled out. A spherical ensemble of discrete clouds with steady outflow or inflow produces a logarithmic profile, but does not account for the highly extended wings. A spherical ensemble with ballistic outflow produces a profile of the first exponential integral function, and fits the observed profile to the continuum level. Although C IV profiles favor the ballistic model, both Mrk 509 and NGC 7469 have significant asymmetry, and Balmer lines with a higher optical depth show higher asymmetry and redshift than all four galaxies.
Wu, C.-C.↗
The absence of rapid X-ray variability in active galaxies
Variations on time scales ranging from minutes to several hours in the X-ray flux from 54 observations of 38 active galaxies are identified. The sample is composed mostly of Seyfert I galaxies but also includes radio galaxies, NELG's BL Lacs and 3C 273. Only NGC 6814 varied on time scales as short as 100 sec. No other source was observed to vary with a time scale of less than 12 hours. Large amplitude short term variations are not a characteristic of the X-ray emission from active galaxies. Upper limits on sigma sub I/I ranged from 2% for Cen A, 5% for NGC 4151, to approximately 20% for sources giving 1 ct/sec in the detector. Three objects NGC 3227, NGC 4151 and MCG 5-23-16 show variability consistent with a time scale of approximately 1 day. Ways to reconcile the rapid variability seen for NGC 6814 (and NGC 4051) with the general stability observed for the other objects are considered.
Tennant, A. F.↗
The X-ray spectrum and time variability of narrow emission line galaxies
X-ray spectral and temporal observations are reported for six narrow emission line galaxies (NELGs), all of which are fitted by power-law X-ray spectra of energy slope 0.8 and have column densities in the line of sight greater than 1 x 10 to the 22nd atoms/sq cm. Three of the objects, NGC 526a, NGC 2110 and MCG-5-23-16 are variable in their X-ray flux, and the latter two, along with NGC 5506 and NGC 7582, showed detectable variability in at least one observation. The measured X-ray properties of these NELGs, which also included NGC 2992, strongly resemble those of previously-measured type 1 Seyferts of the same X-ray luminosity and lead to the conclusion of great similarity between the NELGs and low-luminosity type 1 Seyferts. The implications of these observations for the optical line-emitting region structure of these galaxies are discussed.
Mushotzky, R. F.↗
X-ray observations of the Seyfert 1 galaxies AKN120 and MCG8-11-11
A new X-ray source, H0523-00, with the optically variable Seyfert 1 galaxy AKN 120 is identified. The source has a 2-10 keV X-ray flux of 2 x 10 to the -11th ergs/sq cm s which corresponds to a 2-10 keV X-ray luminosity of 10 to the 44th ergs/s. X-ray observations over a 1.5 year time span combined with contemporaneous optical photometry show a decrease in the optical with no corresponding decrease in the X-ray. In contrast, similar observations of MCG 8-11-11 show a contemporaneous decrease in optical and X-ray fluxes. It is noted that the infrared and X-ray spectral slopes for these two objects are similar, with the optical being steeper by roughly one unit.
Mushotzky, R.↗
The X-ray spectrum and time variability of narrow emission line galaxies
X-ray spectral and temporal observations are reported for six narrow emission line galaxies (NELGs), all of which are fitted by power-law X-ray spectra of energy slope 0.8 and have column densities in the line of sight greater than 1 x 10 to the 22nd atoms/sq cm. Three of the objects, NGC 526a, NGC 2110 and MCG-5-23-16 are variable in their X-ray flux, and the latter two, along with NGC 5506 and NGC 7582, showed detectable variability in at least one observation. The measured X-ray properties of these NELGs, which also included NGC 2992, strongly resemble those of previously-measured type 1 Seyferts of the same X-ray luminosity and lead to the conclusion of great similarity between the NELGs and low-luminosity type 1 Seyferts. The implications of these observations for the optical line-emitting region structure of these galaxies are discussed.
Mushotzky, R.↗
Some evidence for large gravitational redshift in Seyfert galaxy NGC 4151
The photon spectra of two Seyfert galaxies NGC 4151 and MCG 8-11-11 are good experimentally established in the X-ray and gamma range. The annihilation of the high temperature positrons with cold electrons is proposed as the possible mechanism of photon production in the Seyfert galaxy NGC 4151. The photon spectrum of NGC 4151 with its observed features from the soft X to the gamma ray range is described by annihilation of positrons and electrons at temperatures 3 x 10 to the 12th power K and 10 to the 8th power K respectively. The photon spectra from annihilation of unthermalized plasma with above parameters should be shifted to the lower energy by redshift z = 100. In that case the source of photons should be placed closely to the black hole horizon (r approximately equal to 1.0001 r sub g.
Tkaczyk, W.↗