A5048278923- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Particle physics theoretical and experimental studies
- Astrophysics and Star Formation Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Earthquake Detection and Analysis
- Particle Detector Development and Performance
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Computational Physics and Python Applications
- Historical Astronomy and Related Studies
- Engineering and Technology Innovations
- Scientific Research and Discoveries
- Statistics Education and Methodologies
- Astronomical Observations and Instrumentation
National University of Malaysia
2018-2024
Durham University
2015-2020
Ever since the discovery of first active galactic nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures some level in their X-ray spectra. However, despite more than six decades effort, open questions remain: does accretion power impact structure circum-nuclear...
The intrinsic column density (NH) distribution of quasars is poorly known. At the high obscuration end quasar population and for redshifts z < 1, X-ray spectra can only be reliably characterized using broad-band measurements that extend to energies above 10 keV. Using hard observatory NuSTAR, along with archival Chandra XMM-Newton data, we study nine optically selected (from SDSS), candidate Compton-thick (NH > 1.5 × 1024 cm−2) type 2 (CTQSO2s); five new NuSTAR observations are reported...
We present two NuSTAR observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton Swift-BAT, we perform a high-quality broadband spectral analysis AGN over decades energy ($\sim$0.5-100 keV). Previous suggested that is obscured by Compton-thick (CT) column obscuring gas along our line-of-sight. However, lack $\gtrsim$ 10 keV observations, together presence nearby luminous...
Broadband X-ray spectroscopy of the emission produced in coronae active galactic nuclei (AGN) can provide important insights into physical conditions very close to their central supermassive black holes. The temperature Comptonizing plasma that forms corona is manifested through a high-energy cutoff has been difficult directly constrain even brightest AGN because it requires high-quality data at energies above 10 keV. In this paper we present large collection coronal constraints for obscured...
Abstract We present the first full catalog and science results for Nuclear Spectroscopic Telescope Array (NuSTAR) serendipitous survey. The incorporates data taken during 40 months of NuSTAR operation, which provide ≈20 Ms effective exposure time over 331 fields, with an areal coverage 13 deg 2 , 497 sources detected in total 3–24 keV energy range. There are 276 spectroscopic redshifts classifications, largely resulting from our extensive campaign ground-based follow-up. characterize overall...
We identify sources with extremely hard X-ray spectra (i.e., photon indices of Gamma<0.6 in the 13 sq. deg. NuSTAR serendipitous survey, to search for most highly obscured AGNs detected at >10 keV. Eight extreme are identified, and we use data combination lower energy observations (from Chandra, Swift XRT, XMM-Newton) characterize broad-band (0.5-24 keV) spectra. find that all AGNs, including three robust Compton-thick (CT; N_H > 1.5e24 cm^-2) low redshift (z<0.1), a likely-CT AGN higher...
Abstract Obscuration in active galactic nuclei (AGN) provides valuable insights into the nature of material surrounding central engine. Comptonthick AGN (CTAGN), characterised by a column density N H ≥ 1.5 × 10 24 cm −2 , are heavily obscured substantial amounts dust and gas. While X-ray observations primarily used to determine this density, our understanding obscuration properties sub-mm regime, particularly for CTAGN, remains limited. In study, we analyse archival data from Atacama Large...
We present a broad-band (~0.3-70 keV) spectral and temporal analysis of NuSTAR observations the luminous infrared galaxy NGC 6240, combined with archival Chandra, XMM-Newton BeppoSAX data. 6240 is in relatively early merger state two distinct nuclei separated by ~1."5. Previous Chandra have resolved nuclei, showing that they are both active obscured Compton-thick material. Although cannot be NuSTAR, thanks to unprecedented quality data at energies >10 keV, we clearly detect, for first time,...
We present $NuSTAR$ X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested alternate possibility recently switched-off AGN with observed X-rays being lagged echo from torus. Our high-quality data show to be reflection-dominated hard X-rays, but relatively weak neutral Fe K$\alpha$ emission line (equivalent width [EW] $\approx$...
NGC 1448 is one of the nearest luminous galaxies ($L_{8-1000\mu m} >$ 10$^{9} L_{\odot}$) to ours ($z$ $=$ 0.00390), and yet active galactic nucleus (AGN) it hosts was only recently discovered, in 2009. In this paper, we present an analysis nuclear source across three wavebands: mid-infrared (MIR) continuum, optical, X-rays. We observed with Nuclear Spectroscopic Telescope Array (NuSTAR), combined data archival Chandra perform broadband X-ray spectral fitting ($\approx$0.5-40 keV) AGN for...
We analyse high-quality NuSTAR observations of the local (z = 0.011) Seyfert 2 active galactic nucleus (AGN) IC 3639, in conjunction with archival Suzaku and Chandra data. This provides first broadband X-ray spectral analysis source, spanning nearly two decades energy (0.5-30 keV). Previous source below 10 keV indicated strong reflection/obscuration on basis a pronounced iron fluorescence line at 6.4 keV. The hard coverage NuSTAR, together self-consistent toroidal reprocessing models,...
Abstract A geomagnetic storm is a global disturbance of Earth's magnetosphere, occurring as result the interaction with magnetic plasma ejected from Sun. Despite considerable research, comprehensive classification storms for complete solar cycle has not yet been fully developed, most previous studies have limited to specific types. This study, therefore, attempted present statistics 24, detailing occurrence events and classifying them by type intensity (moderate, intense, severe), interval...
Abstract We present a catalog of hard X-ray serendipitous sources detected in the first 80 months observations by Nuclear Spectroscopic Telescope Array (NuSTAR). The NuSTAR survey month (NSS80) has an unprecedented ∼62 Ms effective exposure time over 894 unique fields (a factor 3 increase 40 catalog, NSS40), with areal coverage ∼36 deg 2 , larger than all extragalactic surveys. NSS80 provides 1274 3−24 keV band (822 new detections compared to previous NSS40). Approximately 76% have...
We present $NuSTAR$ observations of four active galactic nuclei (AGN) located within 15 Mpc. These AGN, namely ESO 121-G6, NGC 660, 3486 and 5195, have observed X-ray luminosities $L_{\rm 2-10\ keV, obs} \lesssim$ 10$^{39}$ erg s$^{-1}$, classifying them as low luminosity AGN (LLAGN). perform broadband spectral analysis for the by combining our data with $Chandra$ or $XMM-Newton$ to directly measure their column densities ($N_{\rm H}$) infer intrinsic power. complement archival new high...
Ever since the discovery of first Active Galactic Nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures some level in their X-ray spectra. But despite more than six decades effort, open questions remain: How does accretion power impact structure circum-nuclear...
We present a broadband X-ray spectral analysis of the M51 system, including dual active galactic nuclei (AGN) and several off-nuclear point sources. Using deep observation by NuSTAR, new high-resolution coverage M51b Chandra, latest torus models, we measure intrinsic luminosities AGN in these galaxies. The M51a is found to be Compton thick, both have very low accretion rates ($\lambda_{\rm Edd} <10^{-4}$). latter surprising considering that galaxies are process merging, which generally...
Abstract In this paper, we present the analysis of stellar system HIP 101227 to determine actual number components in system, and their properties. We use dynamical modeling complex spectrophotometric (involving atmospheric modeling) techniques with recent data, physical properties orbital solution for respectively, better accuracy than past studies. Based on our analysis, found that is more consistent being a quadruple rather binary or triple as suggested by previous The total mass...
Abstract In this paper, we present the broadband (0.5–195 keV) X-ray spectral analysis for one of newly detected AGNs in Swift-BAT 105 month Hard Survey Catalog, NGC 4117. According to our ongoing research on low luminosity from catalog, examine whether they are indeed or heavily obscured AGNs. One sample is 4117, where discover it could be potentially a CTAGN. Therefore 4117 detail, combined high energy data with XMM-Newton and Swift-XRT, fitted spectra simultaneously using...
Kertas ini membentangkan pemerhatian Observatori Sinar-X Chandra terhadap Sagittarius A* (Sgr A*) yang diambil sepanjang dua dekad pertama operasi observatori tersebut antara tahun 1999 dan 2019. Spektrum sinar-X bagi 143 dianalisis untuk mengkaji evolusi Sgr 20 melalui ciri utamanya, iaitu kecerahan (luminositi), ketumpatan gas debu (NH) indeks foton (Γ). Secara amnya, berada dalam keadaan stabil tempoh pemerhatian, dengan purata luminositi intrinsik julat tenaga 2 – 8 keV iaitu, L2-8...
We present a catalog of hard X-ray serendipitous sources detected in the first 80 months observations by Nuclear Spectroscopic Telescope Array (NuSTAR). The NuSTAR survey 80-month (NSS80) has an unprecedented $\sim$ 62 Ms effective exposure time over 894 unique fields (a factor three increase 40-month catalog), with areal coverage $\sim $36 deg$^2$, larger than all extragalactic surveys. NSS80 provides 1274 $3-24$ keV band (822 new detections compared to previous catalog). Approximately 76%...
Hard X-ray-selected samples of Active Galactic Nuclei (AGN) provide one the cleanest views supermassive black hole accretion, but are biased against objects obscured by Compton-thick gas column densities $N_{\rm H}$ $>$ 10$^{24}$ cm$^{-2}$. To tackle this issue, we present NuSTAR Local AGN Distribution Survey (NuLANDS)$-$a legacy sample 122 nearby ($z$ $<$ 0.044) primarily selected to have warm infrared colors from IRAS between 25$-$60 $\mu$m. We show that optically classified type 1 and 2...
To answer NASA’s call for a sensitive X-ray observatory in the 2030s, we present High Energy Probe (HEX-P) mission concept. HEX-P is designed to provide required capabilities explore current scientific questions and make new discoveries with broadband that simultaneously measures sources from 0.2 80 keV. HEX-P’s main goals include: 1) understand growth of supermassive black holes how they drive galaxy evolution; 2) lower mass populations white dwarfs, neutron stars, stellar-mass nearby...
Abstract Hard X-ray-selected samples of active galactic nuclei (AGN) provide one the cleanest views supermassive black hole accretion but are biased against objects obscured by Compton-thick gas column densities N H > 10 24 cm −2 . To tackle this issue, we present NuSTAR Local AGN Distribution Survey (NuLANDS)—a legacy sample 122 nearby ( z < 0.044) primarily selected to have warm infrared colors from IRAS between 25 and 60 μ m. We show that optically classified Type 1 2 in NuLANDS...
Abstract This study presented the effect of a geomagnetic storm that was driven by coronal mass ejection (CME) on ionospheric disturbance dynamo (Ddyn) near equatorial region. The Ddyn variation calculated using Earth’s magnetic field’s H component data. On other hand, Space Weather Prediction Center (SWPC) provides data CME events utilized in this analysis. is identified time (Dst) index. Multiple 8 May 2024 and 9 triggered two-step with great type where Dst values are -352 nT (10 2024,...