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Your search keyword '"Fürst, F"' showing total 28 results
Start Over Author "Fürst, F" Publisher oxford university press (oup)
28 results on '"Fürst, F"'

2. The first mm detection of a neutron star high-mass X-ray binary

Author

van den Eijnden, J, primary, Sidoli, L, additional, Díaz Trigo, M, additional, Degenaar, N, additional, El Mellah, I, additional, Fürst, F, additional, Grinberg, V, additional, Kretschmar, P, additional, Martínez-Núñez, S, additional, Miller-Jones, J C A, additional, Postnov, K, additional, and Russell, T D, additional

Published
2023
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3. The chameleon on the branches: spectral state transition and dips in NGC 247 ULX-1

Author

MIT Kavli Institute for Astrophysics and Space Research, D’Aì, A, Pinto, C, Del Santo, M, Pintore, F, Soria, R, Robba, A, Ambrosi, E, Alston, W, Barret, D, Fabian, AC, Fürst, F, Kara, E, Kosec, P, Middleton, M, Roberts, T, Rodriguez-Castillo, G, Walton, DJ, MIT Kavli Institute for Astrophysics and Space Research, D’Aì, A, Pinto, C, Del Santo, M, Pintore, F, Soria, R, Robba, A, Ambrosi, E, Alston, W, Barret, D, Fabian, AC, Fürst, F, Kara, E, Kosec, P, Middleton, M, Roberts, T, Rodriguez-Castillo, G, and Walton, DJ

Abstract

ABSTRACT Soft Ultra-Luminous X-ray (ULXs) sources are a subclass of the ULXs that can switch from a supersoft spectral state, where most of the luminosity is emitted below 1 keV, to a soft spectral state with significant emission above 1 keV. In a few systems, dips have been observed. The mechanism behind this state transition and the dips nature are still debated. To investigate these issues, we obtained a long XMM–Newton monitoring campaign of a member of this class, NGC 247 ULX-1. We computed the hardness–intensity diagram for the whole data set and identified two different branches: the normal branch and the dipping branch, which we study with four and three hardness–intensity resolved spectra, respectively. All seven spectra are well described by two thermal components: a colder (kTbb ∼ 0.1–0.2 keV) blackbody, interpreted as emission from the photosphere of a radiatively driven wind, and a hotter (kTdisc ∼ 0.6 keV) multicolour disc blackbody, likely due to reprocessing of radiation emitted from the innermost regions. In addition, a complex pattern of emission and absorption lines has been taken into account based on previous high-resolution spectroscopic results. We studied the evolution of spectral parameters and flux of the two thermal components along the two branches and discuss two scenarios possibly connecting the state transition and the dipping phenomenon. One is based on geometrical occultation of the emitting regions, the other invokes the onset of a propeller effect.

Published
2022

4. Discovery of a soft X-ray lag in the ultraluminous X-ray source NGC 1313 X-1

Author

MIT Kavli Institute for Astrophysics and Space Research, Kara, E, Pinto, C, Walton, D J, Alston, W N, Bachetti, M, Barret, D, Brightman, M, Canizares, C R, Earnshaw, H P, Fabian, A C, Fürst, F, Kosec, P, Middleton, M J, Roberts, T P, Soria, R, Tao, L, Webb, N A, MIT Kavli Institute for Astrophysics and Space Research, Kara, E, Pinto, C, Walton, D J, Alston, W N, Bachetti, M, Barret, D, Brightman, M, Canizares, C R, Earnshaw, H P, Fabian, A C, Fürst, F, Kosec, P, Middleton, M J, Roberts, T P, Soria, R, Tao, L, and Webb, N A

Abstract

© 2019 The Author(s). Ultraluminous X-ray sources (ULXs) provide a unique opportunity to probe the geometry and energetics of super-Eddington accretion. The radiative processes involved in super-Eddington accretion are not well understood, and so studying correlated variability between different energy bands can provide insights into the causal connection between different emitting regions. We present a spectral-timing analysis of NGC 1313 X-1 from a recent XMM–Newton campaign. The spectra can be decomposed into two thermal-like components, the hotter of which may originate from the inner accretion disc, and the cooler from an optically thick outflow. We find correlated variability between hard (2–10 keV) and soft (0.3–2 keV) bands on kilosecond time-scales, and find a soft lag of ∼150 s. The covariance spectrum suggests that emission contributing to the lags is largely associated with the hotter of the two thermal-like components, likely originating from the inner accretion flow. This is only the third ULX to exhibit soft lags. The lags range over three orders of magnitude in amplitude, but all three are ∼5–20 per cent of the corresponding characteristic variability time-scales. If these soft lags can be understood in the context of a unified picture of ULXs, then lag time-scales may provide constraints on the density and extent of radiatively driven outflows.

Published
2022

5. The Chameleon on the branches: spectral state transition and dips in NGC 247 ULX-1

Author

D’Aì, A, primary, Pinto, C, additional, Del Santo, M, additional, Pintore, F, additional, Soria, R, additional, Robba, A, additional, Ambrosi, E, additional, Alston, W, additional, Barret, D, additional, Fabian, A C, additional, Fürst, F, additional, Kara, E, additional, Kosec, P, additional, Middleton, M, additional, Roberts, T, additional, Rodriguez-Castillo, G, additional, and Walton, D J, additional

Published
2021
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6. The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM–Newton, Chandra , and NuSTAR

Author

MIT Kavli Institute for Astrophysics and Space Research, Walton, DJ, Pinto, C, Nowak, M, Bachetti, M, Sathyaprakash, R, Kara, E, Roberts, TP, Soria, R, Brightman, M, Canizares, CR, Earnshaw, HP, Fürst, F, Heida, M, Middleton, MJ, Stern, D, Tao, L, Webb, N, Alston, WN, Barret, D, Fabian, AC, Harrison, FA, Kosec, P, MIT Kavli Institute for Astrophysics and Space Research, Walton, DJ, Pinto, C, Nowak, M, Bachetti, M, Sathyaprakash, R, Kara, E, Roberts, TP, Soria, R, Brightman, M, Canizares, CR, Earnshaw, HP, Fürst, F, Heida, M, Middleton, MJ, Stern, D, Tao, L, Webb, N, Alston, WN, Barret, D, Fabian, AC, Harrison, FA, and Kosec, P

Abstract

© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We present results from the major coordinated X-ray observing programme on the ULX NGC 1313 X-1 performed in 2017, combining XMM-Newton, Chandra, and NuSTAR, focusing on the evolution of the broad-band (∼0.3-30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above ∼10-15 keV, qualitatively similar to the ULX Holmberg IX X-1. We model the multi-epoch data with two-component accretion disc models designed to approximate super-Eddington accretion, allowing for both a black hole and a neutron star accretor. With regards to the hotter disc component, the data trace out two distinct tracks in the luminosity-temperature plane, with larger emitting radii and lower temperatures seen at higher observed fluxes. Despite this apparent anticorrelation, each of these tracks individually shows a positive luminosity-temperature relation. Both are broadly consistent with L ∝ T4, as expected for blackbody emission with a constant area, and also with L ∝ T2, as may be expected for an advection-dominated disc around a black hole. We consider a variety of possibilities for this unusual behaviour. Scenarios in which the innermost flow is suddenly blocked from view by outer regions of the super-Eddington disc/wind can explain the luminosity-temperature behaviour, but are difficult to reconcile with the lack of strong variability at higher energies, assuming this emission arises from the most compact regions. Instead, we may be seeing evidence for further radial stratification of the accretion flow than is included in the simple models considered, with a combination of winds and advection resulting in the suppressed high-energy variability.

Published
2021

7. Discovery of a soft X-ray lag in the ultraluminous X-ray source NGC 1313 X-1

Author

Kara, E, Pinto, C, Walton, DJ, Alston, WN, Bachetti, M, Barret, D, Brightman, M, Canizares, CR, Earnshaw, HP, Fabian, AC, Fürst, F, Kosec, P, Middleton, MJ, Roberts, TP, Soria, R, Tao, L, Webb, NA, Kara, E, Pinto, C, Walton, DJ, Alston, WN, Bachetti, M, Barret, D, Brightman, M, Canizares, CR, Earnshaw, HP, Fabian, AC, Fürst, F, Kosec, P, Middleton, MJ, Roberts, TP, Soria, R, Tao, L, and Webb, NA

Abstract

© 2019 The Author(s). Ultraluminous X-ray sources (ULXs) provide a unique opportunity to probe the geometry and energetics of super-Eddington accretion. The radiative processes involved in super-Eddington accretion are not well understood, and so studying correlated variability between different energy bands can provide insights into the causal connection between different emitting regions. We present a spectral-timing analysis of NGC 1313 X-1 from a recent XMM–Newton campaign. The spectra can be decomposed into two thermal-like components, the hotter of which may originate from the inner accretion disc, and the cooler from an optically thick outflow. We find correlated variability between hard (2–10 keV) and soft (0.3–2 keV) bands on kilosecond time-scales, and find a soft lag of ∼150 s. The covariance spectrum suggests that emission contributing to the lags is largely associated with the hotter of the two thermal-like components, likely originating from the inner accretion flow. This is only the third ULX to exhibit soft lags. The lags range over three orders of magnitude in amplitude, but all three are ∼5–20 per cent of the corresponding characteristic variability time-scales. If these soft lags can be understood in the context of a unified picture of ULXs, then lag time-scales may provide constraints on the density and extent of radiatively driven outflows.

Published
2021

10. A new transient ultraluminous X-ray source in NGC 7090

Author

Walton, D J, primary, Heida, M, additional, Bachetti, M, additional, Fürst, F, additional, Brightman, M, additional, Earnshaw, H, additional, Evans, P A, additional, Fabian, A C, additional, Grefenstette, B W, additional, Harrison, F A, additional, Israel, G L, additional, Lansbury, G B, additional, Middleton, M J, additional, Pike, S, additional, Rana, V, additional, Roberts, T P, additional, Rodriguez Castillo, G A, additional, Salvaterra, R, additional, Song, X, additional, and Stern, D, additional

Published
2020
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12. The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM–Newton, Chandra, and NuSTAR

Author

Walton, D J, primary, Pinto, C, additional, Nowak, M, additional, Bachetti, M, additional, Sathyaprakash, R, additional, Kara, E, additional, Roberts, T P, additional, Soria, R, additional, Brightman, M, additional, Canizares, C R, additional, Earnshaw, H P, additional, Fürst, F, additional, Heida, M, additional, Middleton, M J, additional, Stern, D, additional, Tao, L, additional, Webb, N, additional, Alston, W N, additional, Barret, D, additional, Fabian, A C, additional, Harrison, F A, additional, and Kosec, P, additional

Published
2020
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13. Searching for ultra-fast outflows in AGN using variability spectra

Author

Igo, Z, primary, Parker, M L, additional, Matzeu, G A, additional, Alston, W, additional, Alvarez Crespo, N, additional, Fürst, F, additional, Buisson, D J K, additional, Lobban, A, additional, Joyce, A M, additional, Mallick, L, additional, Schartel, N, additional, and Santos-Lleó, M, additional

Published
2020
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14. Discovery of a soft X-ray lag in the ultraluminous X-ray source NGC 1313 X-1

Author

Kara, E, primary, Pinto, C, additional, Walton, D J, additional, Alston, W N, additional, Bachetti, M, additional, Barret, D, additional, Brightman, M, additional, Canizares, C R, additional, Earnshaw, H P, additional, Fabian, A C, additional, Fürst, F, additional, Kosec, P, additional, Middleton, M J, additional, Roberts, T P, additional, Soria, R, additional, Tao, L, additional, and Webb, N A, additional

Published
2019
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15. MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries

Author

Buisson, D J K, primary, Fabian, A C, additional, Barret, D, additional, Fürst, F, additional, Gandhi, P, additional, García, J A, additional, Kara, E, additional, Madsen, K K, additional, Miller, J M, additional, Parker, M L, additional, Shaw, A W, additional, Tomsick, J A, additional, and Walton, D J, additional

Published
2019
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16. On the magnetic field in M51 ULX-8

Author

Middleton, M J, primary, Brightman, M, additional, Pintore, F, additional, Bachetti, M, additional, Fabian, A C, additional, Fürst, F, additional, and Walton, D J, additional

Published
2019
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23. A precessing Be disc as a possible model for occultation events in GX 304−1

Author

Kühnel, M., primary, Rothschild, R. E., additional, Okazaki, A. T., additional, Müller, S., additional, Pottschmidt, K., additional, Ballhausen, R., additional, Choi, J., additional, Kreykenbohm, I., additional, Fürst, F., additional, Marcu-Cheatham, D. M., additional, Hemphill, P., additional, Sagredo, M., additional, Kretschmar, P., additional, Martínez-Núñez, S., additional, Torrejón, J. M., additional, Staubert, R., additional, and Wilms, J., additional

Published
2017
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28. Disentangling the complex broad-band X-ray spectrum of IRAS 13197−1627 with NuSTAR, XMM–Newton and Suzaku

Author

D. Stern, Fiona A. Harrison, A. C. Fabian, Giorgio Matt, Murray Brightman, Anne M. Lohfink, Guido Risaliti, Michael Parker, Dom Walton, Felix Fürst, Giovanni Miniutti, Walton, D. J., Brightman, M., Risaliti, G., Fabian, A. C., Fürst, F., Harrison, F. A., Lohfink, A., Matt, G., Miniutti, G., Parker, M. L., and Stern, D.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, X-ray, FOS: Physical sciences, Astronomy, Broad band, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Galaxy, Rotating black hole, Space and Planetary Science, Homogeneous, Astrophysics of Galaxies (astro-ph.GA), Reprocessor, Ionization, 0103 physical sciences, Outflow, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We present results from a coordinated $XMM$-$Newton$+$NuSTAR$ observation of the type 1.8 Seyfert galaxy IRAS 13197-1627. This is a highly complex source, with strong contributions from relativistic reflection from the inner accretion disk, neutral absorption and further reprocessing by more distant material, and ionised absorption from an outflow. We undertake a detailed spectral analysis combining the broadband coverage provided by $XMM$-$Newton$+$NuSTAR$ with a multi-epoch approach incorporating archival observations performed by $XMM$-$Newton$ and $Suzaku$. Our focus is on characterising the reflection from the inner accretion disk, which previous works have suggested may dominate the AGN emission, and constraining the black hole spin. Using lamppost disk reflection models, we find that the results for the inner disk are largely insensitive to assumptions regarding the geometry of the distant reprocessor and the precise form of the illuminating X-ray continuum. However, these results do depend on the treatment of the iron abundance of the distant absorber/reprocessor. The multi-epoch data favour a scenario in which the AGN is chemically homogeneous, and we find that a rapidly rotating black hole is preferred, with $a^* \geq 0.7$, but a slowly-rotating black hole is not strongly excluded. In addition to the results for the inner disk, we also find that both the neutral and ionised absorbers vary from epoch to epoch, implying that both have some degree of inhomogeneity in their structure., 15 pages, 7 figures, accepted for publication in MNRAS

Published
2017
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