Altan Baykal
A5101670624- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- Families in Therapy and Culture
- Astronomy and Astrophysical Research
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Linguistics and Cultural Studies
- Astronomical Observations and Instrumentation
- Magnetic confinement fusion research
- Turkish Literature and Culture
- Stock Market Forecasting Methods
- Monetary Policy and Economic Impact
Middle East Technical University
2017-2023
ABSTRACT We investigate timing and spectral characteristics of the transient X-ray pulsar 2S 1417−624 during its 2018 outburst with NICER follow up observations. describe spectra high-energy cut-off partial covering fraction absorption (PCFA) model present flux-dependent changes source outburst. Utilizing correlation-mode switching parameters, we confirm previously reported sub-critical to critical regime transitions argue that secondary transition from gas-dominated radiation...
In this study, we examine the long term torque noise fluctuations of persistent Xray binaries Her X-1, Vela GX 301-2, CEN X-3, 4U 1538-53, OAO 1657-415 and 1626-67 using historical pulse frequency measurements provided by CGRO/BATSE Fermi/GBM. We find that known disk-fed sources exhibit $1/\omega^{2}$ red component in their power density spectra which is saturated over timescales. On other hand, wind-fed form a clear white with occasional transient disk formation imprint $1/\omega$ type...
ABSTRACT We present a timing and noise analysis of the Be/X-ray binary system Swift J0243.6+6124 during its 2017–2018 super-Eddington outburst using NICER/XTI observations. apply synthetic pulse to enrich Fermi/GBM spin frequency history source with new measurements from NICER/XTI. show that profiles switch double-peaked single-peaked when X-ray luminosity drops below ∼7 × 1036 erg s−1. suggest this transitional is associated transition pencil beam pattern hybrid Coulomb interactions become...
Using \emph{RXTE}, \emph{Chandra}, \emph{XMM-Newton} and \emph{Swift} observations, we for the first time construct power spectra torque noise strengths of magnetars. For some sources, measure strong red on timescales months to years which might be a consequence their outbursts. We compare magnetars with those radio pulsars by investigating possible correlations spin-down rate, magnetic field age. these correlations, find that magnetar are obeying similar trends pulsars. On contrary, do not...
We present analysis of RXTE--PCA observations GX 1+4 between March 3, 2001 and January 31, 2003 together with the CGRO--BATSE X-ray flux frequency derivative time series 1991 1999. From timing RXTE-PCA observations, we are able to phase connect pulse arrival times source within two different intervals obtain corresponding solutions. Using these times, contribute long term history source. look for episodic correlations anti-correlations torque luminosity using find that correlation state...
This is a White Paper in support of the mission concept Large Observatory for X-ray Timing (LOFT), proposed as medium-sized ESA mission. We discuss potential LOFT study high-mass binaries and ultra-luminous sources. For summary, we refer to paper.
We report on the timing characteristics of MXB 0656-072 throughout its 2007-2008 type I outbursts utilising RXTE/PCA and Fermi/GBM data. Using pulse technique, we explore spin frequency evolution source during this interval. Subsequently, by examining torque-luminosity relation, show that overall is substantially in line with Ghosh-Lamb model. Furthermore, residuals frequencies do not exhibit clear orbital modulations, which possibly indicate system observed a relatively top view. In...