Дисертації з теми "X-ray pulsars"
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Gavriil, Fotis Panagiotis. "Magnetar-like x-ray bursts from anomalous x-ray pulsars." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100371.
Повний текст джерелаTang, Pui-shan Anisia, and 鄧佩姗. "Thermal X-ray pulses resulting from pulsar glitches." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B29790992.
Повний текст джерелаTang, Pui-shan Anisia. "Thermal X-ray pulses resulting from pulsar glitches /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2089675X.
Повний текст джерелаInam, Sitki Cagdas. "X-ray Observations Of Accretion Powered Pulsars." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605552/index.pdf.
Повний текст джерела吳國偉 and Kwok-wai Eddie Ng. "Neutrino production from accreting X-ray pulsars." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31211811.
Повний текст джерелаNg, Kwok-wai Eddie. "Neutrino production from accreting X-ray pulsars /." [Hong Kong : University of Hong Kong], 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13745013.
Повний текст джерелаIcdem, Burcin. "Viscous Time Scale In Accreting Powered Pulsars And Anomalous X-ray Pulsars." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613373/index.pdf.
Повний текст джерелаDib, Rim. "RXTE monitoring of 5 anomalous x-ray pulsars." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66730.
Повний текст джерелаI first present a long-term (1998-2006) study of AXP 4U 0142+61 in which we show that from 2000 to 2006 the pulse profile of the pulsar slowly evolved, and the pulsed flux increased by 29+/-8%.
AXP 4U 0142+61 then entered an active phase in 2006 March that lasted several months and included several X-ray bursts. I present a study of the behaviour of AXP 4U 0142+61 during this active phase.
I then present a long-term (1998-2007) study of AXPs RXS J170849.0-400910 and 1E 1841-045 in which we report on four new glitches. We show that AXPs are very active glitchers and that some AXP glitch properties are challenging to interpret in standard glitch models. Furthermore, we note that AXP glitches appear to fall in two classes: radiatively loud and radiatively quiet.
Finally, I present a long-term (1997-2008) study of AXP 1E 1048.1-5937 in which we show that three timing events occurred cont
Les pulsars X anormaux (AXPs) sont des étoiles à neutrons qui partagent certaines propriétés spécifiques. Ils sont dits "anormaux'" car leur luminosité est supérieure au taux de perte de leur énergie de rotation. Selon le modèle des "magnétars'', ces pulsars sont des étoiles à neutrons jeunes, isolées, et dont la luminosité provient d'un grand réservoir d'énergie magnétique. Cinq de ces AXPs (1E 2259+586, 4U 0142+61, RXS J170849.0-400910, 1E 1841-045, 1E 1048.1-5937) sont sous observation depuis 1997 dans le cadre d'un programme de surveillance utilisant le Rossi X-ray Timing Explorer (RXTE). Le but de ce programme est d'étudier les propriétés temporelles de ces pulsars tels les changements soudains de fréquence, et d'étudier leurs propriétés radiatives tels les changements de flux pulsé, les changements de profil de pulse, et les sursauts d'énergie. Ce programme de surveillance aide à obtenir une description détaillée des propriétés de ces objets, qui servira à tester les modèles théoriques des AXPs, dont le modèle des "magnétars''. Dans cette thèse, je présente quelques-unes de mes contributions au programme de surveillance.
D'abord, je présente une étude à long terme (1998-2006) du AXP 4U 0142+61 où nous montrons qu'entre 2000 et 2006, le profil de pulse du pulsar a lentement évolué, et que le flux pulsé a augmenté de 29+/-8%.
Le AXP 4U 0142+61 est ensuite entré dans une phase active en mars 2006, dans laquelle il a émis plusieurs sursauts d'énergie. Je présente une étude du comportement du AXP 4U 0142+61 pendant cette phase active.
Ensuite, je présente une étude à long terme (1998-2007) des AXPs RXS J170849.0-400910 et 1E 1841-045. Dans cette étude, nous avons détecté quatre nouveaux changements soudains de fréquence. Nous montrons que dans le contexte de changements soudains de fréquence, les AXPs sont très actifs. Nous montrons auss
Camero, Arranz Ascension. "Accreting X-Ray pulsars. The high energy picture." Doctoral thesis, Universitat de València, 2007. http://hdl.handle.net/10803/9484.
Повний текст джерелаGavriil, Fotis P. "Long-term monitoring of anomalous X-ray pulsars with the rossi x-ray timing explorer." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33763.
Повний текст джерелаMannings, Vincent. "TeV gamma-ray emission from accreting binary pulsars." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6297/.
Повний текст джерелаChadwick, Mary Paula. "Very high energy cosmic gamma rays from radio and X-ray pulsars." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6720/.
Повний текст джерела高樹豐 and Shu-fung Ko. "Emission morphologies and phase-resolved spectrum of gamma ray pulsar." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224489.
Повний текст джерелаKo, Shu-fung. "Emission morphologies and phase-resolved spectrum of gamma ray pulsar /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B23476370.
Повний текст джерелаRIGOSELLI, MICHELA. "X-ray emission from the magnetic polar caps of old rotation-powered pulsars." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/277373.
Повний текст джерелаNeutron stars are the remnants of massive stars whose cores collapse during the supernova explosions. The project of this PhD Thesis consisted in the study of the X-ray emission from isolated neutron stars older than about 100000 years. The work was based mainly on data obtained with the XMM-Newton satellite (ESA). To extract the best possible information from the data, I implemented a maximum likelihood (ML) technique and used it to derive the X-ray spectra and pulse profiles of several old pulsars, that were then studied with state-of-the-art models of X-ray emission. The Thesis is structured as follows: in the first three chapters I outline the main properties of neutron stars, with a major focus on the thermal and nonthermal processes that produce X-rays. The nonthermal X-rays are produced by relativistic particles accelerated by rotation-induced electric fields and moving along the magnetic field lines. A fraction of these particles is accelerated backward and returns on the stellar surface, heating the magnetic polar caps. The thermal component, that can be produced by the whole stellar surface or by small hot spots, can be described, in a first approximation, by a blackbody. However, the presence of intense surface magnetic fields strongly affects the properties of matter, and the emergent radiation is widely anisotropic. In Chapter 4, I describe how I generated synthetic spectra and pulse profiles using thermal emission models that consider polar caps covered by a magnetized hydrogen atmosphere or with a condensed iron surface. I relied on an existing software that, given a set of stellar parameters, evaluates the emerging intensity of the radiation. A second software, which I adapted on the sources I analyzed in the Thesis, collects the contribution of surface elements which are in view at different rotation phases from a stationary observer. Then, in Chapter 5, I describe how I implemented an analysis software that relies on the ML method. It estimates the most probable number of source and background counts by comparing the spatial distribution of the observed counts with the expected distribution for a point source plus an uniform background. I demonstrated that the ML method is particularly effective for dim sources, as most old pulsars are. Subsequently, I applied the methods described above to some old pulsars. In Chapter 6, I report the analysis of PSR J0726-2612, a radio pulsars that shares some properties with the radio-silent XDINSs, as the long period, the high magnetic field, and the thermal X-ray emission from the cooling surface. Thanks to an in-depth analysis of the combined spectrum and pulse profile, I showed that the presence of radio pulses from PSR J0726-2612, as well as the absence from the XDINSs, might simply be due to different viewing geometries. In Chapter 7, I present the case of PSR B0943+10, a pulsar with a nonthermal and thermal X-ray spectrum but that, despite being an aligned rotator, has a large pulsed fraction. I could reconcile the two opposite properties analyzing with the ML the spectrum and the pulse profile, and considering the magnetic beaming of a magnetized atmosphere model, that well fits the thermal component. In Chapter 8, I applied the ML method to seven old and dim pulsars, of which four had controversial published results, and three were so far undetected. I found convincing evidence of thermal emission only in the phase-averaged spectrum of two of them, plus a hint for a thermal pulsed spectrum in a third object. Finally, I considered all the old thermal emitters and I compared their observed temperatures, radii and luminosities to the expectations of the current theoretical models for these objects. In particular, I found that the emitting area are generally in agreement with the polar cap regions evaluated in a dipole approximation, if the combined effects of geometry projections plus realistic thermal models (as the magnetic atmosphere) are taken into account.
Wang, Yu, and 王禹. "Non-thermal X-ray and soft gamma-ray radiation from the young pulsars." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196467.
Повний текст джерелаpublished_or_final_version
Physics
Doctoral
Doctor of Philosophy
Huang, Hsiu-Hui. "X-ray and Optical observations of Globular Clusters and Pulsars." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-123830.
Повний текст джерелаAlbano, Alessandra. "Spectral and timing properties of transient anomalous x-ray pulsars." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427009.
Повний текст джерелаNegli ultimi anni, grazie alla nuova generazione di satelliti (in particolare Chandra e XMM-Newton), è divenuto possibile osservare, con alta risoluzione, un crescente numero di stelle di neutroni isolate (INSs) che emettono raggi X. Molte nuove classi di INSs che emettono raggi X sono state scoperte, nessuna delle quali emette nel radio, o con proprietà nel radio in disaccordo con quelle delle PSRs: X-ray Dim Isolated Neutron Stars (XDINSs), Anomalous X-ray Pulsars (AXPs) e Soft Gamma-ray Repeaters (SGRs), Central Compact Objects (CCOs), Rotating Radio Transient (RRATs, in un caso). AXPs e SGRs sono due gruppi di INSs con caratteristiche peculiari, formati in tutto da 15 oggetti (6 SGRs e 9 AXPs più una candidata). Anche se meno numerose delle PSRs, questi oggetti sono stati ampiamente studiati proprio in virtù delle loro proprietà peculiari ed estreme. Gli SGRs mostrano bursts e flares con intensità tra le $\sim 10^2$ e le $\sim 10^{11}$ volte la loro luminosit\`a quiescente in banda X ($10^{34} - 10^{36} \ {\rm erg/s}$). Nell'ultima decade fenomeni spettrali transienti sono stati osservati in alcune AXPs, con un aumento di luminosità compreso tra alcune decine e alcune centinaia di volte la luminosità di quiescenza. Le molte similarità nelle proprietà spettrali e di timing di SGRs e AXPs portano a suggerire che questi oggetti possano essere nient'altro che differenti manifestazioni dello stesso fenomeno. Si ritiene che queste sorgenti ospitino una Magnetar, una stella di neutroni ultra magnetizzata con campo magnetico pari a $\sim 10^{14}-10^{15}$ G. Nel modello Magnetar l'emissione da SGRs e AXPs proviene dall'espansione del campo magnetico ultra intenso piuttosto che ad energie di tipo rotazionale, gravitazionale o termico. Nelle Magnetars il campo magnetico esterno potrebbe acquisire una componente di tipo toroidale, come conseguenza della deformazione della crosta della stella indotta dall'intensissimo campo magnetico interno. Il risultato netto è un twist della magnetosfera della stella; inoltre le correnti richieste per supportare il campo non potenziale potrebbero dar luogo ad una profondità ottica sufficientemente spessa per il resonant cyclotron scattering (RCS). Di conseguenza ci si aspetta una distorsione negli spettri termici, dato che i fotoni primari guadagnano energia nei ripetuti urti con le particelle cariche presenti nella magnetosfera. Gli spettri all'uscita della magnetosfera twistata in presenza di RCS sono stati studiati da svariati autori (Lyutikov e Gavriil, 2006, Fernandez e Thompson, 2007, Nobili Turolla e Zane, 2008) e questo modello è stato applicato agli spettri di SGRs e AXPs da Rea et al. 2008 and Zane et al., 2008. Il codice montecarlo 3D creato da Nobili, Turolla e Zane (2008) è lo strumento più avanzato per calcolare curve di luce e spettri. Gli spettri così ottenuti possono essere descritti in termini di 5 parametri: l'angolo di twist $\Delta \phi$, la velocità di bulk degli elettroni $\beta$, la temperatura superficiale $T$ e i due angoli geometrici $\chi$ e $\xi$ ($\xi$ è il disassamento tra campo magnetico e asse di rotazione mentre $\chi$ è l'inclinazione della linea di vista rispetto all'asse di rotazione). In questo lavoro, riadattato dall'articolo Albano et al., 2010, viene presentato un ampio studio dei profili pulsati e dell'evoluzione spettrale delle due TAXPs a partire dall'inizio dell'outburst. Confrontando i dati di timing con le curve di luce sintentiche ottenute con il modello di magnetosfera twistata (Nobili, Turolla e Zane, 2008) siamo stati in grado di stimare l'evoluzione temporale del parametri fisici della sorgente (temperatura superficiale e area emittente, energia degli elettroni, angolo di twist). I fit del profilo pulsato ci permettono anche di asserire la eometria del sistema, e cioè l'angolo fra campo magnetico e asse di rotazione e quello tra asse di rotazione e linea di vista. I modelli spettrali, ottenuti dai valori dei parametri derivati dall'analisi di timing, danno dei fit accettabili dei dati di XMM-Newton.
Coburn, Wayne. "A study of magnetic fields of accreting x-ray pulsars with the Rossi x-ray timing explorer /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3015845.
Повний текст джерелаBeklen, Elif. "X-ray And Optical Observations Of High Mass X-ray Binaries." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612636/index.pdf.
Повний текст джерелаSasmaz, Mus Sinem. "X-ray And Timing Properties Of Anomalous X-ray Pulsar 1e 2259+586." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608625/index.pdf.
Повний текст джерелаGonzález, Galán Ana. "Fundamental properties of High Mass X-ray Binaries." Doctoral thesis, Universidad de Alicante, 2014. http://hdl.handle.net/10045/41723.
Повний текст джерелаChakrabarty, Deepto Prince Thomas A. Prince Thomas A. "Hard X-ray detection and timing of accretion-powered pulsars with BATSE /." Diss., Pasadena, Calif. : California Institute of Technology, 1996. http://resolver.caltech.edu/CaltechETD:etd-09022008-132322.
Повний текст джерелаKumar, Harsha Sanjeev. "X-ray studies of highly magnetized neutron stars and their environs." Astrophysical Journal Letters, 2008. http://hdl.handle.net/1993/22091.
Повний текст джерелаSahiner, Seyda. "X-ray Spectral And Timing Studies Of The High Mass X-ray Binary Pulsar 4u 1907+09." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610941/index.pdf.
Повний текст джерелаBeklen, Elif. "Timing Observations From Rossi X-ray Timing Explorer (rxte)." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1260199/index.pdf.
Повний текст джерелаMarini, Bettolo Cecilia. "Performance Studies and Star Tracking for PoGOLite." Doctoral thesis, KTH, Partikel- och astropartikelfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13015.
Повний текст джерелаQC20100629
Pivovaroff, Michael James 1971. "X-ray astronomy with CCDs : calibration of the advanced CCD imaging spectrometer and observations of rotation-powered pulsars." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9026.
Повний текст джерелаIncludes bibliographical references.
This dissertation concerns the use of charge coupled devices (CCDs) for X-ray astronomy. Part I of this thesis focuses on the calibration of the Advanced CCD Imaging Spectrometer (ACIS), one of the two primary focal plane instruments on the Chandra X-ray Observatory. I begin by presenting a series of measurements made using undispersed synchrotron radiation. I analyzed the results of these experiments to extract parameters necessary to model the absolute detection efficiency of CCDs used as reference standards for ACIS characterization. I also discuss a novel "mesh" technique I pioneered to non-destructively measure the sub-pixel structure of CCDs, including the channel stops and gates. This work also provided a valuable tool for understanding the way charge is collected inside certain regions of the ACIS detectors. Guided by the results of the mesh experiments, I performed additional measurements to constrain recombination effects in the channel stops. Part II of this thesis concerns the X-ray properties of rotation-powered (radio) pulsars. High energy observations serve as a powerful diagnostic of the energetics and emission mechanisms of neutron stars. Associations between pulsars and the remnants of their supernovae provide independent measures of the distance and age of neutron stars, as well as constraints on their initial velocities, magnetic fields, and spin periods. I analyze ASCA and ROSAT observations of three young pulsars which are particularly well-suited for addressing these issues. I also present observations of the rotation-powered pulsar with the highest known magnetic field, and describe how the results relate to anomalous X-ray pulsars, another type of neutron star. Finally, I analyze Chandra observations of the supernova remnant Cas A. These data fully demonstrate the capabilities of ACIS and reveal a previously unknown point source at the center of the remnant.
by Michael James Pivovaroff.
Ph.D.
Falkner, Sebastian [Verfasser], Jörn [Akademischer Betreuer] Wilms, Silas Gutachter] Laycock, and Jörn [Gutachter] [Wilms. "Modeling X-ray pulsars in curved space-time / Sebastian Falkner ; Gutachter: Silas Laycock, Jörn Wilms ; Betreuer: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/116380682X/34.
Повний текст джерелаFalkner, Sebastian Verfasser], Jörn [Akademischer Betreuer] [Wilms, Silas Gutachter] Laycock, and Jörn [Gutachter] [Wilms. "Modeling X-ray pulsars in curved space-time / Sebastian Falkner ; Gutachter: Silas Laycock, Jörn Wilms ; Betreuer: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/116380682X/34.
Повний текст джерелаVybornov, Vadim [Verfasser], and Andrea [Akademischer Betreuer] Santangelo. "Changes in X-ray spectra of accreting pulsars on short and long time scales / Vadim Vybornov ; Betreuer: Andrea Santangelo." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1179180968/34.
Повний текст джерелаYukita, M., A. Ptak, A. E. Hornschemeier, D. Wik, T. J. Maccarone, K. Pottschmidt, A. Zezas, et al. "Identification of the Hard X-Ray Source Dominating the E > 25 keV Emission of the Nearby Galaxy M31." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623858.
Повний текст джерелаCUOFANO, Carmine. "Magnetic fields generated by r-modes in accreting millisecond pulsars." Doctoral thesis, Università degli studi di Ferrara, 2010. http://hdl.handle.net/11392/2389313.
Повний текст джерелаKulebi, Baybars. "The Broad-band Noise Characteristics Of Selected Cataclysmic Variables (cvs), Anomalous X-ray Pulsars (axps) And Soft Gamma Repeaters (sgrs)." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608117/index.pdf.
Повний текст джерелаFarrell, Sean Adam Physical Environmental & Mathematical Sciences Australian Defence Force Academy UNSW. "The multi-coloured universe of 2S 0114+650." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Physical, Environmental and Mathematical Sciences, 2007. http://handle.unsw.edu.au/1959.4/38692.
Повний текст джерелаMüller, Sebastian [Verfasser], and Jörn [Akademischer Betreuer] Wilms. "Observations of the X-ray Pulsars XTE J1946+274, 4U 0115+634, and GX 304-1 / Sebastian Müller. Gutachter: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2013. http://d-nb.info/1065380526/34.
Повний текст джерелаMüller, Sebastian Verfasser], and Jörn [Akademischer Betreuer] [Wilms. "Observations of the X-ray Pulsars XTE J1946+274, 4U 0115+634, and GX 304-1 / Sebastian Müller. Gutachter: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2013. http://d-nb.info/1065380526/34.
Повний текст джерелаTaskin, Ozgur Mustafa. "Analysis Of The Physical Properties Of Different Types Of Neutron Stars." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606665/index.pdf.
Повний текст джерела1e12 G) and with characteristic ages (tau) less than 1e7 years is questioned. We proposed that such pulsars might occur as a result of the disruption of high-mass X-ray binary systems after a second supernova explosion. In these binaries, mass accretion on to the surface of X-ray pulsars may lead to the decrease in the magnetic field from its value at birth (B similar to 1e12 &ndash
1e13 G) down to B <
1e12 G similar to the processes in low-mass X-ray binaries. In the second part we put together many observational data of SGRs and AXPs and analyzed them with the main purpose of the removal of contradiction between the real age (t) of these objects and their characteristic times of period change (tau). SGRs and AXPs are neutron stars that undergo star-quakes. Magnetic activity increases from time to time. We suggest that as a result of these processes plasma is ejected from the NS and propeller mechanism starts to work. Due to propeller effect dP/dt increases, tau decreases. Indeed, high dP/dt values are observed in SGRs and in half of the AXPs. Then, for a long time NS looses its activity, its dP/dt decreases, tau increases and rapid cooling begins. It seems that there is a possible transition between each NS stage (AXP,SGR,dim). This transient cycle may be repeated once or several times until the spin period of the neutron star becomes P >
10 - 12 s. Observational data and mainly the data of AXP 1E 1048-5937 and DRQNS RX J1308.8+2127 support this idea. In the third part dependence of the X-ray luminosity (Lx) of young single pulsars, due to ejection of relativistic particles, on electric field intensity, rate of rotational energy loss (dE/dt), magnetic field, period and some other parameters of neutron stars are discussed. Influence of the magnetic field and effects of some other parameters of neutron stars on the Lx - dE/dt and the Lx - tau(characteristic time) relations are considered. Evolutionary factors also play an important role in our considerations. Only the pulsars whose X-ray luminosity in the 2 &ndash
10 keV energy band is greater than 1033 erg/s have pulsar wind nebula around them. The pulsars from which gamma-ray radiation has been observed have low X-ray luminosity in general.
Serim, Muhammed Mirac. "Timing Properties Of Recently Discovered Soft Gamma Repeaters." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614803/index.pdf.
Повний текст джерелаCaballero, Doménech Isabel. "X-ray observations of the accreting Be, X-ray binary pulsar A 0535+26 in outburst." Tübingen, Neue Str. 16 : I. Caballero Doménech, 2009. http://d-nb.info/995113327/34.
Повний текст джерелаMatheson, Heather. "X-ray observations of the young pulsar wind nebula G21.5–0.9 and the evolved pulsar wind nebulae CTB 87 (G74.9+1.2) and G63.7+1.1." IOP Publishing Ltd. for The American Astronomical Society, 2010. http://hdl.handle.net/1993/30163.
Повний текст джерелаBergh, Magnus. "Interaction of Ultrashort X-ray Pulses with Material." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8274.
Повний текст джерелаHartman, Jacob M. Ph D. Massachusetts Institute of Technology. "X-ray timing of the accreting millisecond pulsar SAX J1808.4-3658." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45413.
Повний текст джерелаIncludes bibliographical references (p. 105-114).
We present a 7 yr timing study of the 2.5 ms X-ray pulsar SAX J1808.4-3658, an X-ray transient with a recurrence time of =2 yr, using data from the Rossi X-ray Timing Explorer covering 4 transient outbursts (1998-2005). Substantial pulse shape variability, both stochastic and systematic, was observed during each outburst. Analysis of the systematic pulse shape changes suggests that, as an outburst dims, the X-ray "hot spot" on the pulsar surface drifts longitudinally and a second hot spot may appear. The overall pulse shape variability limits the ability to measure spin frequency evolution within a given X-ray outburst (and calls previous zi measurements of this source into question), with typical upper limits of Jil < 2.5 x 10-14 Hz s-1 (2a). However, combining data from all the outbursts shows with high (6 a) significance that the pulsar is undergoing long-term spin down at a rate /i = (-5.6 ± 2.0) x 10-16 Hz s-1, with most of the spin evolution occurring during X-ray quiescence. We discuss the possible contributions of magnetic propeller torques, magnetic dipole radiation, and gravitational radiation to the measured spin down, setting an upper limit of B < 1.5 x 108 G for the pulsar's surface dipole magnetic field and Q < 4.4 x 1036 g cm2 for the mass quadrupole moment. We also measured an orbital period derivative of Porb = (3.5 + 0.2) x 10-12 s s-1 We identify a strong anti-correlation between the fractional amplitude of the harmonic (r2) and the X-ray flux (fx) in the persistent pulsations of four sources: SAX J1808.4-3658, IGR J00291+5934, and XTE J1751-305, XTE J1807-294. These sources exhibit a powerlaw relationship r2 x( fx7 with slopes ranging from y = -0.47 to -0.70. The three other accreting millisecond pulsars that we analyzed, XTE J0929-314, XTE J1814-338, and HETE J1900.1-2455, do not as fully explore a wide range of fluxes, but they too seem to obey a similar relation. We argue that these trends may be evidence of the recession of the accretion disk as the outbursts dim. We examine the energy dependence of the persistent pulsations and thermonuclear burst oscillations from SAX J1808.4-3658.
We confirm the soft phase lags previously discovered from this source, and we discover that these phase lags increase as the source flux decays slowly following its peak flux. When the source decay becomes rapid and the outburst enters its flaring tail stage, this relationship reverses, and the phase lags diminish as the flux dims further. This result, along with the pulse profile changes observed at the beginning of the flairing tail stage, suggests an abrupt change in the geometry of the accretion disk and column at this time in the outburst. In contrast, the thermonuclear burst oscillation timing does not show appreciable lags, and the burst oscillation phases and fractional amplitudes appear to be relatively independent of energy.
by Jacob M. Hartman.
Ph.D.
Davies, Simon Robert. "The supernova remnant G109.1-1.0 and the X-ray pulsar 1E2259+586." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252711.
Повний текст джерелаCaballero, Doménech Isabel [Verfasser]. "X-ray observations of the accreting Be, X-ray binary pulsar A 0535+26 in outburst / vorgelegt von Isabel Caballero Doménech." Tübingen, Neue Str. 16 : I. Caballero Doménech, 2009. http://d-nb.info/995113327/34.
Повний текст джерелаCarstairs, Ian Ruthven. "Kernel density estimators applied to hard X-ray observations of the Crab Pulsar." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315292.
Повний текст джерелаBarszczak, Sardinha Anna Luiza. "Coherent imaging of nano-objects with ultra-short X-ray pulses." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX006/document.
Повний текст джерелаThe use of X-rays is fundamental to obtain a spatial resolution in the order of the dozen of nanometers. The duration of the flashes of radiation is placed between the dozen of femtoseconds (1 fs =10-15 s) to the hundreds of attoseconds (1as=10-18 s). During this time frame nano-objects are static in time, image wise it translates as a precise image. Exciting these nano-objects with flashes of X-ray beams it is possible to follow its temporal evolution and record a "movie" of the evolution due to excitation. This type of information is extremely important since it can allow the identification of intermediary structural states and therefore attaining a better understanding of their reactional power.This type of studies it is making its debut in the scientific community due to the recent development of ultra-fast and intense X-ray sources needed to perform this type of imaging. The referenced source is a free electron laser (FEL) and there are only tree of them in the world nowadays. One in Germany, one in the USA and one in Japan. The small amount of FELs is mainly due to its elevated costs. From some years the LOA has shown that lasers can also provide an X-ray beam in the femtosecond region and intense enough to produce images of nano-objects with equivalent temporal and spatial resolutions.This present thesis was built in tree phases: realization of an X-ray laser source, circularly polarized; realization of a new improved imaging system and testing of the nano-samples possessing nano-structures. These nano-structures have a velocity of evolution after excitation in the range of 100 fs. These studies have had place at LOA, LCLS, Laboratoire de Chimie-Physique, Matière et Rayonnement (LCPMR), the CEA de Saclay, BESSY-II in Germany. These cooperations have insured a specific training and expertise in the world of nanometric imaging based on the new technique developed during this work
Yu, Wayne Hong. "Application of X-ray pulsar navigation| A characterization of the Earth orbit trade space." Thesis, University of Maryland, College Park, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10012594.
Повний текст джерелаThe potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of X-ray photons from milli-second pulsars (MSP) to perform space navigation. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This thesis is the study of pulsar XNAV measurements for extended Kalman filter (EKF) tracking performance within a wide trade space of bounded Earth orbits, using a simulation of existing X-ray detector space hardware. An example of an X-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in 2016.
The study shows that the closed Earth orbit for XNAV performance is reliant on the orbit semi-major axis and eccentricity as well as orbit inclination. These parameters are the primary drivers of pulsar measurement availability and significantly influence the natural spacecraft orbit dynamics. Sensitivity to initial orbit determination error growth due to the scarcity of XNAV measurements within an orbital period require appropriate timing of initial XNAV measurements. The orbit angles of argument of perigee and right ascension of the ascending node, alongside the other orbit parameters, complete the initial cadence of XNAV measurements. The performance of initial XNAV measurements then propagates throughout the experimental period.
Camacho, Garibay Abraham. "Dynamics of Highly Charged Finite Systems Induced by Intense X-ray Pulses." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-212203.
Повний текст джерелаFabris, Nicola. "Instrumentation for Photon Handling of XUV and Soft X-ray Ultrafast Pulses." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3425791.
Повний текст джерела