Scaling of an 85 GHz Gyrotron to Operate at 94 GHz

Bergeron, G. L.; Czarnaski, M. A.; Rhinewine, M.

doi:10.21236/ada212756

Cited by 7 publications

(13 citation statements)

References 3 publications

(4 reference statements)

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“…A decrease in the Hα luminosity of IC 3599 by a factor of 10 in less than a year (Mannheim et al 1996) is perhaps independent evidence that the total ionizing luminosity of this object does vary by a large factor. On the other hand, there were no significant changes in the optical continuum flux or Fe II line intensities in PHL 1092 between optical spectra coincidentally taken in 1979 August (Bergeron & Kunth 1980, 1984 one month after the Einstein observation, and in 1992 September (Kwan et al 1995) eight months after ROSAT observed the QSO in its X-ray high state.…”

Section: Long-term Variabilitymentioning

confidence: 78%

“…It has long been known that there are high-luminosity analogs of this class, the prototype of which is I Zw 1 (e.g., Phillips 1976), which also have weak forbidden lines, narrow permitted lines, and strong Fe II. One of the most extreme narrow-line Fe II QSOs is PHL 1092 (Bergeron & Kunth 1980, 1984Kwan et al 1995). Its Fe II λ4570/Hβ ratio is 5.3, and its line widths are only 1800 km s −1 (Bergeron & Kunth 1984).…”

Section: Introductionmentioning

confidence: 99%

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Extreme X-Ray Variability in the Narrow-Line QSO PHL 1092

Förster¹,

Halpern²

1996

ApJ

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A ROSAT observation of the narrow-line Fe II QSO PHL 1092 shows rapid variability that requires an efficiency of at least 0.13, exceeding the theoretical maximum for an accretion disk around a non-rotating black hole. Plausible explanations for this high efficiency incorporate anisotropic emission and/or accretion onto a rapidly rotating black hole, the latter recently suggested by Kwan et al. as a mechanism for generating PHL 1092's strong Fe II lines by mechanical heating in an accretion disk. The soft X-ray luminosity of PHL 1092 had also increased by a factor of 21 over the weak Einstein detection, to more than 5 × 10 46 ergs s −1 . Its photon spectral index of 4.2 is among the steepest of any AGN. These X-ray properties are characteristic of narrow-line Seyfert 1 galaxies, of which PHL 1092 is evidently a very luminous member. Narrow-line QSOs also extend a significant correlation between X-ray luminosity and X-ray spectral index which we have found among a large sample of optically-selected, narrow-line Seyfert 1 galaxies observed by ROSAT.

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Section: Long-term Variabilitymentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Extreme X-Ray Variability in the Narrow-Line QSO PHL 1092

Förster¹,

Halpern²

1996

ApJ

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“…respect to older spectra (e.g. Bergeron & Kunth 1980). Here we compare the two HET optical spectra of PHL 1092 which were obtained in 2008 and 2010.…”

Section: Optical Het Spectra: Comparison Between the 2008 And 2010 Obmentioning

confidence: 99%

“…Here we consider the case of PHL 1092 which recently became one of the most extreme X-ray weak non-BAL quasars known (see below). PHL 1092 (z = 0.396) is a radio-quiet quasar with outstanding Fe II emission (Bergeron & Kunth 1980, 1984Kwan et al 1995). Its broad line widths of ∼1800 km s −1 and a ratio [O III]λ5007/Hβ ∼ 0.9, together with the strong Fe II emission (Fe II/Hβ = 1.81), classify PHL 1092 as a high-luminosity Narrow-Line Seyfert 1 (NLS1) galaxy (Osterbrock & Pogge 1985).…”

mentioning

confidence: 99%

Insights on the X-ray weak quasar phenomenon from XMM-Newton monitoring of PHL 1092

Miniutti

Brandt²,

Schneider³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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PHL 1092 is a z ∼ 0.4 high‐luminosity counterpart of the class of Narrow‐Line Seyfert 1 galaxies. In 2008, PHL 1092 was found to be in a remarkably low X‐ray flux state during an XMM–Newton observation. Its 2 keV flux density had dropped by a factor of ∼260 with respect to a previous observation performed 4.5 yr earlier. The ultraviolet (UV) flux remained almost constant, resulting in a significant steepening of the optical‐to‐X‐ray slope αox from −1.57 to −2.51, making PHL 1092 one of the most extreme X‐ray weak quasars with no observed broad absorption lines (BALs) in the UV. We have monitored the source since 2008 with three further XMM–Newton observations, producing a simultaneous UV and X‐ray data base spanning almost 10 yr in total in the activity of the source. Our monitoring programme demonstrates that the αox variability in PHL 1092 is entirely driven by long‐term X‐ray flux changes. We apply a series of physically motivated models with the goal of explaining the UV‐to‐X‐ray spectral energy distribution and the extreme X‐ray and αox variability. We consider three possible models. (i) A breathing corona scenario in which the size of the X‐ray‐emitting corona is correlated with the X‐ray flux. In this case, the lowest X‐ray flux states of PHL 1092 are associated with an almost complete collapse of the X‐ray corona down to the marginal stable orbit. (ii) An absorption scenario in which the X‐ray flux variability is entirely due to intervening absorption. If so, PHL 1092 is a quasar with standard X‐ray output for its optical luminosity, appearing as X‐ray weak at times due to absorption. (iii) A disc‐reflection‐dominated scenario in which the X‐ray‐emitting corona is confined within a few gravitational radii from the black hole at all times. In this case, the intrinsic variability of PHL 1092 only needs to be a factor of ∼10 rather than the observed factor of ∼260. We discuss these scenarios in the context of non‐BAL X‐ray weak quasars.

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“…PHL 1092 (B = 16.7; z = 0.396) is a luminous Narrow-Line Seyfert 1 (NLS1) class quasar that is one of the strongest optical Fe ii emitters known (Bergeron & Kunth 1980). Such objects have been generally found to have extreme X-ray spectral and variability properties, and it appears likely that their exceptional X-ray/optical characteristics arise as the result of an extreme value of a primary physical parameter (see Brandt & Boller 1998 for a recent discussion).…”

Section: Introductionmentioning

confidence: 99%

ROSAT High-Resolution Imager monitoring of extreme X-ray variability in the narrow-line quasar PHL 1092

Brandt

Boller

Fabian

et al. 1999

Monthly Notices of the Royal Astronomical Society

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We report results from an 18‐d ROSAT High‐Resolution Imager (HRI) monitoring campaign on the ultrasoft narrow‐line Seyfert 1 (NLS1) class quasar PHL 1092. This luminous, radio‐quiet quasar showed strong X‐ray variability in a short ROSAT Position‐Sensitive Proportional Counter observation, and ROSAT HRI monitoring of the similar object IRAS 13224‐3809 revealed extreme variability on intermediate time‐scales. We wanted to determine whether remarkable X‐ray variability persistently occurs in PHL 1092, and we also wanted to search for outstanding variability events that constrain emission processes. Given the large luminosity of PHL 1092 (∼ 5 × 1045 erg s‐1 in the HRI band), we detect extremely rapid and large‐amplitude X‐ray variability throughout our monitoring. The maximum observed variability amplitude is a factor of ≈14, and in the most rapid variability event the HRI count rate increases by a factor of ≈ 3.8 in a rest‐frame time interval of <3580 s. The most rapid event has a rate change of luminosity of >1.3 × 1042 erg s‐2, making it the most extreme such event we are aware of from a radio‐quiet quasar. Standard `radiative efficiency limit' arguments imply a radiative efficiency larger than can be achieved by accretion on to a Kerr black hole rotating at the maximum plausible rate, although we point out that such arguments depend upon the geometry of initial radiation release. Relativistic motions of the X‐ray source are probably causing the radiative efficiency limit to break down; such relativistic motions have also been inferred in the similar NLS1‐class quasar PKS 0558‐504.

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Scaling of an 85 GHz Gyrotron to Operate at 94 GHz

Cited by 7 publications

References 3 publications

Extreme X-Ray Variability in the Narrow-Line QSO PHL 1092

Extreme X-Ray Variability in the Narrow-Line QSO PHL 1092

Insights on the X-ray weak quasar phenomenon from XMM-Newton monitoring of PHL 1092

ROSAT High-Resolution Imager monitoring of extreme X-ray variability in the narrow-line quasar PHL 1092

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