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Classification of X-ray Binaries in NGC 6946 with the use of Multiwavelength Data
Senay Avdan, Hasan Avdan, Eda Sonbas +1
We identified X-ray binary (XRB) candidates in the galaxy NGC 6946 using archival {\it Chandra} data. A total of 98 XRB candidates were detected within the 0.38 keV energy range…
X-ray to Mid-IR Spectral Energy Distributions: A Catalog of X-ray Selected AGNs in the XMM-COSMOS Survey
Şeyda Şen, Eda Sonbas, Ece Kilerci +4
We present a component-resolved analysis of the IR--X-ray connection in a sample of 104 spectroscopically confirmed Type~1 AGN. By combining \xmm, \swift/UVOT, and new high--angula…
Optical Counterparts of Two Candidate Ultraluminous X-ray Sources in NGC 4536
H. Avdan, E. Sonbas, K. S. Dhuga +7
Archival {\it XMM-Newton}, {\it Chandra} and {\it Hubble Space Telescope (HST)} data have been used to study the X-ray and optical properties of two candidate ultraluminous X-ray s…
Optical Counterparts of ULXs in NGC 1672
S. Allak, A. Akyuz, E. Sonbas +1
In this work, we deploy archival data from {\it HST}, {\it Chandra}, {\it XMM-Newton}, and {\it Swift-XRT}, to probe the nature of 9 candidate ULXs in NGC 1672. Specifically, our s…
The Disk-Corona Model and Mass Estimates of the Ultraluminous X-ray Source Holmberg IX X-1
Ramandeep Gill, Eda Sonbas, Kalvir S. Dhuga +1
The origin of the variable X-ray emission in the keV energy range of ultraluminous X-ray sources (ULXs) remains unclear, making it difficult to constrain the mass of th…
A Temporal Scale to Track the Spectral Transitions in Low-Mass X-ray Binaries
E. Sonbas, K. Mohamed, K. S. Dhuga +1
The results of a temporal analysis of observations for a sample of nine low-mass X-ray binaries (LMXBs) are presented. Of these sources, five host a neutron star (NS) primary (4U16…
A Minimal Timescale for the Continuum in 4U 1608-52 and Aql X-1
K. Mohamed, E. Sonbas, K. S. Dhuga +4
Similar to black-hole X-ray binary (BHXRB) transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries (NSXRBs). Using a method based on wavelet…
A Minimal Time Scale for the Spectral States of GX 339-4
E. Sonbas, K. Mohamed, K. S. Dhuga +2
Black hole transients are known to undergo spectral transitions that form q-shaped tracks on a hardness intensity diagram. In this work, we use archival RXTE data to extract a char…
Evidence of an X-Ray-UV Spectral Correlation in ULXs
E. Sonbas, K. S. Dhuga, E. Gogus
By comparing the ratio of flux densities in the X-ray and UV wavebands by way of the spectral optical-X-Ray index, , we explore the relation between the emissions in the re…
The Bright X-Ray Source in NGC 3413
E. Sonbas, K. S. Dhuga, E. Göğüş
The emission-line dwarf galaxy NGC 3413 is known to host a bright X-ray source near its optical center. The 0.3-10 keV luminosity of this source is estimated to be approximately 10…
A Study of Low-Mass X-Ray Binaries in the Low-Luminosity Regime
E. Sonbas, K. S. Dhuga, E. Gogus
A recent study of a small sample of X-ray binaries (XRBs) suggests a significant softening of spectra of neutron star (NS) binaries as compared to black hole (BH) binaries in the l…
Properties of the Intergalactic Magnetic Field Constrained by Gamma-ray Observations of Gamma-Ray Bursts
P. Veres, C. D. Dermer, K. S. Dhuga
The magnetic field in intergalactic space gives important information about magnetogenesis in the early universe. The properties of this field can be probed by searching for radiat…
Gamma-Ray Bursts: Temporal Scales and the Bulk Lorentz Factor
E. Sonbas, G. A. MacLachlan, K. S. Dhuga +3
For a sample of Swift and Fermi GRBs, we show that the minimum variability timescale and the spectral lag of the prompt emission is related to the bulk Lorentz factor in a complex…
X - Ray Flares and Their Connection With Prompt Emission in GRBs
E. Sonbas, G. A. MacLachlan, A. Shenoy +2
We use a wavelet technique to investigate the time variations in the light curves from a sample of GRBs detected by Fermi and Swift. We focus primarily on the behavior of the flari…
Probing Curvature Effects in the Fermi GRB 110920
A. Shenoy, E. Sonbas, C. Dermer +7
Curvature effects in Gamma-ray bursts (GRBs) have long been a source of considerable interest. In a collimated relativistic GRB jet, photons that are off-axis relative to the obser…
A New Correlation Between GRB X-Ray Flares And The Prompt Emission
E. Sonbas, G. A. MacLachlan, A. Shenoy +2
From a sample of GRBs detected by the and missions, we have extracted the minimum variability time scales for temporal structures in the light curves associated wit…
The Hurst Exponent of Fermi GRBs
Glen MacLachlan, Ashwin Shenoy, Eda Sonbas +5
Using a wavelet decomposition technique, we have extracted the Hurst exponent for a sample of 46 long and 22 short Gamma-ray bursts (GRBs) detected by the Gamma-ray Burst Monitor (…
Infrahumps detected in Kepler light curve of V1504 Cygni
Robert Coyne, Ashwin Shenoy, Glen MacLachlan +6
We present a power spectral density analysis of the short cadence Kepler data for the cataclysmic variable V1504 Cygni. We identify three distinct periods: the orbital period (1.66…
The Minimum Variability Time Scale and its Relation to Pulse Profiles of Fermi GRBs
G. A. MacLachlan, A. Shenoy, E. Sonbas +4
We present a direct link between the minimum variability time scales extracted through a wavelet decomposition and the rise times of the shortest pulses extracted via fits of 34 Fe…
Minimum Variability Time Scales of Long and Short GRBs
G. A. MacLachlan, A. Shenoy, E. Sonbas +7
We have investigated the time variations in the light curves from a sample of long and short Fermi/GBM Gamma ray bursts (GRBs) using an impartial wavelet analysis. The results indi…
Follow the BAT: Monitoring Swift BAT FoV for Prompt Optical Emission from Gamma-ray Bursts
T. N. Ukwatta, J. T. Linnemann, K. S. Dhuga +1
We investigate the feasibility of implementing a system called 'Follow the BAT' that will coordinate ground-based robotic optical and near infrared (NIR) telescopes to monitor the…
The Lag-Luminosity Relation in the GRB Source-Frame: An Investigation with Swift BAT Bursts
T. N. Ukwatta, K. S. Dhuga, M. Stamatikos +12
Spectral lag, which is defined as the difference in time of arrival of high and low energy photons, is a common feature in Gamma-ray Bursts (GRBs). Previous investigations have sho…
A New Frequency-Luminosity Relation for Long GRBs?
T. N. Ukwatta, K. S. Dhuga, D. C. Morris +7
We have studied power density spectra (PDS) of 206 long Gamma-Ray Bursts (GRBs). We fitted the PDS with a simple power-law and extracted the exponent of the power-law (alpha) and t…
Sensitivity of the FERMI Detectors to Gamma-Ray Bursts from Evaporating Primordial Black Holes (PBHs)
T. N. Ukwatta, Jane H. MacGibbon, W. C. Parke +6
Primordial Black Holes (PBHs), which may have been created in the early Universe, are predicted to be detectable by their Hawking radiation. The Fermi Gamma-ray Space Telescope obs…