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Showing 1-10 of about 10 results.
Designing miniature x-ray optics for the SmallSat lunar science mission concept CubeXKashyap, Vinay L.Hong, JaesubRomaine, SuzanneSethares, LeandraCotroneo, VincenzoSpiga, DanieleNittler, LarryDOI: info:10.1364/AO.393554v. 595560
Kashyap, Vinay L., Hong, Jaesub, Romaine, Suzanne, Sethares, Leandra, Cotroneo, Vincenzo, Spiga, Daniele, and Nittler, Larry. 2020. "Designing miniature x-ray optics for the SmallSat lunar science mission concept CubeX." Applied Optics 59:5560.
ID: 158153
Type: article
Authors: Kashyap, Vinay L.; Hong, Jaesub; Romaine, Suzanne; Sethares, Leandra; Cotroneo, Vincenzo; Spiga, Daniele; Nittler, Larry
Deep Chandra Survey of the Small Magellanic Cloud. III. Formation Efficiency of High-mass X-Ray BinariesAntoniou, ValliaZezas, AndreasDrake, Jeremy J.Badenes, CarlesHaberl, FrankWright, Nicholas J.Hong, JaesubDi Stefano, RosanneGaetz, Terrance J.Long, Knox S.Plucinsky, Paul P.Sasaki, ManamiWilliams, Benjamin F.Winkler, P. FrankSMC XVP collaborationDOI: info:10.3847/1538-4357/ab4a7av. 88720
Antoniou, Vallia, Zezas, Andreas, Drake, Jeremy J., Badenes, Carles, Haberl, Frank, Wright, Nicholas J., Hong, Jaesub, Di Stefano, Rosanne, Gaetz, Terrance J., Long, Knox S., Plucinsky, Paul P., Sasaki, Manami, Williams, Benjamin F., Winkler, P. Frank, and SMC XVP collaboration. 2019. "Deep Chandra Survey of the Small Magellanic Cloud. III. Formation Efficiency of High-mass X-Ray Binaries." The Astrophysical Journal 887:20.
ID: 154539
Type: article
Authors: Antoniou, Vallia; Zezas, Andreas; Drake, Jeremy J.; Badenes, Carles; Haberl, Frank; Wright, Nicholas J.; Hong, Jaesub; Di Stefano, Rosanne; Gaetz, Terrance J.; Long, Knox S.; Plucinsky, Paul P.; Sasaki, Manami; Williams, Benjamin F.; Winkler, P. Frank; SMC XVP collaboration
Abstract: We have compiled the most complete census of high-mass X-ray binaries (HMXBs) in the Small Magellanic Cloud with the aim to investigate the formation efficiency of young accreting binaries in its low-metallicity environment. In total, we use 123 X-ray sources with detections in our Chandra X-ray Visionary Program (XVP), supplemented by 14 additional (likely and confirmed) HMXBs identified by Haberl & Sturm that fall within the XVP area, but are neither detected in our survey (nine sources) nor matched with any of the 127 sources identified in the XVP data (five sources). Specifically, we examine the number ratio of the HMXBs [N(HMXBs)] to (a) the number of OB stars, (b) the local star formation rate (SFR), and (c) the stellar mass produced during the specific star formation burst, all as a function of the age of their parent stellar populations. Each of these indicators serves a different role, but in all cases we find that the HMXB formation efficiency increases as a function of time (following a burst of star formation) up to ∼40─60 Myr, and then gradually decreases. The formation efficiency peaks at ∼30─40 Myr with average rates of {\text{}}{{N}}({HMXB})/{SFR}={339}-83+78 {({M}ȯ /{yr})}-1, and N(HMXB)/M \star =({8.74}-0.92+1.0)× {10}-6 {M}ȯ -1, in good agreement with previous estimates of the average formation efficiency in the broad ∼20─60 Myr age range.
Neutron Stars and Black Holes in the Small Magellanic Cloud: The SMC NuSTAR Legacy SurveyLazzarini, M.Williams, B. F.Hornschemeier, A. E.Antoniou, ValliaVasilopoulos, G.Haberl, F.Vulic, N.Yukita, M.Zezas, AndreasBodaghee, A.Lehmer, B. D.Maccarone, T. J.Ptak, A.Wik, D.Fornasini, Francesca M.Hong, JaesubKennea, J. A.Tomsick, J. A.Venters, T.Udalski, A.Cassity, A.DOI: info:10.3847/1538-4357/ab3f32v. 8842
Lazzarini, M., Williams, B. F., Hornschemeier, A. E., Antoniou, Vallia, Vasilopoulos, G., Haberl, F., Vulic, N., Yukita, M., Zezas, Andreas, Bodaghee, A., Lehmer, B. D., Maccarone, T. J., Ptak, A., Wik, D., Fornasini, Francesca M., Hong, Jaesub, Kennea, J. A., Tomsick, J. A., Venters, T., Udalski, A., and Cassity, A. 2019. "Neutron Stars and Black Holes in the Small Magellanic Cloud: The SMC NuSTAR Legacy Survey." The Astrophysical Journal 884:2.
ID: 154709
Type: article
Authors: Lazzarini, M.; Williams, B. F.; Hornschemeier, A. E.; Antoniou, Vallia; Vasilopoulos, G.; Haberl, F.; Vulic, N.; Yukita, M.; Zezas, Andreas; Bodaghee, A.; Lehmer, B. D.; Maccarone, T. J.; Ptak, A.; Wik, D.; Fornasini, Francesca M.; Hong, Jaesub; Kennea, J. A.; Tomsick, J. A.; Venters, T.; Udalski, A.; Cassity, A.
Abstract: We present a source catalog from the first deep hard X-ray (E > 10 keV) survey of the Small Magellanic Cloud (SMC), the Nuclear Spectroscopic Telescope Array (NuSTAR) Legacy Survey of the SMC. We observed three fields, for a total exposure time of 1 Ms, along the bar of this nearby star-forming galaxy. Fields were chosen for their young stellar and accreting binary populations. We detected 10 sources above a 3σ significance level (4-25 keV) and obtained upper limits on an additional 40 sources. We reached a 3σ limiting luminosity in the 4-25 keV band of ̃1035 erg s-1, allowing us to probe fainter X-ray binary (XRB) populations than has been possible with other extragalactic NuSTAR surveys. We used hard X-ray colors and luminosities to constrain the compact-object type, exploiting the spectral differences between accreting black holes and neutron stars at E > 10 keV. Several of our sources demonstrate variability consistent with previously observed behavior. We confirmed pulsations for seven pulsars in our 3σ sample. We present the first detection of pulsations from a Be-XRB, SXP 305 (CXO J005215.4-73191), with an X-ray pulse period of 305.69 ± 0.16 s and a likely orbital period of ̃1160-1180 days. Bright sources (≳5 × 1036 erg s-1) in our sample have compact-object classifications consistent with their previously reported types in the literature. Lower-luminosity sources (≲5 × 1036 erg s-1) have X-ray colors and luminosities consistent with multiple classifications. We raise questions about possible spectral differences at low luminosity between SMC pulsars and the Galactic pulsars used to create the diagnostic diagrams.
Anticorrelation between X-ray luminosity and pulsed fraction in the Small Magellanic Cloud pulsar SXP 1323Yang, JunZezas, AndreasCoe, Malcolm J.Drake, Jeremy J.Hong, JaesubLaycock, Silas G. T.Wik, Daniel R.DOI: info:10.1093/mnrasl/sly085v. 479L1–L6
Yang, Jun, Zezas, Andreas, Coe, Malcolm J., Drake, Jeremy J., Hong, Jaesub, Laycock, Silas G. T., and Wik, Daniel R. 2018. "Anticorrelation between X-ray luminosity and pulsed fraction in the Small Magellanic Cloud pulsar SXP 1323." Monthly Notices of the Royal Astronomical Society 479:L1– L6.
ID: 149147
Type: article
Authors: Yang, Jun; Zezas, Andreas; Coe, Malcolm J.; Drake, Jeremy J.; Hong, Jaesub; Laycock, Silas G. T.; Wik, Daniel R.
Abstract: We report the evidence for the anticorrelation between pulsed fraction (PF) and luminosity of the X-ray pulsar SXP 1323, found for the first time in a luminosity range 1035-1037 erg s-1 from observations spanning 15 yr. The phenomenon of a decrease in X-ray PF when the source flux increases has been observed in our pipeline analysis of other X-ray pulsars in the Small Magellanic Cloud. It is expected that the luminosity under a certain value decreases as the PF decreases due to the propeller effect. Above the propeller region, an anticorrelation between the PF and the flux might occur either as a result of an increase in the unpulsed component of the total emission or a decrease of the pulsed component. Additional modes of accretion may also be possible, such as spherical accretion and a change in emission geometry. At higher mass accretion rates, the accretion disc could also extend closer to the neutron star surface, where a reduced inner radius leads to hotter inner disc emission. These modes of plasma accretion may affect the change in the beam configuration to fan-beam dominant emission.
Deep Chandra Survey of the Small Magellanic Cloud. II. Timing Analysis of X-Ray PulsarsHong, JaesubAntoniou, ValliaZezas, AndreasHaberl, FrankSasaki, ManamiDrake, Jeremy J.Plucinsky, Paul P.Laycock, SilasDOI: info:10.3847/1538-4357/aa8953v. 84726
Hong, Jaesub, Antoniou, Vallia, Zezas, Andreas, Haberl, Frank, Sasaki, Manami, Drake, Jeremy J., Plucinsky, Paul P., and Laycock, Silas. 2017. "Deep Chandra Survey of the Small Magellanic Cloud. II. Timing Analysis of X-Ray Pulsars." The Astrophysical Journal 847:26.
ID: 144706
Type: article
Authors: Hong, Jaesub; Antoniou, Vallia; Zezas, Andreas; Haberl, Frank; Sasaki, Manami; Drake, Jeremy J.; Plucinsky, Paul P.; Laycock, Silas
Abstract: We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg2 region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb-Scargle and epoch-folding techniques, we detected periodic modulations from 20 pulsars and a new candidate pulsar. The survey also covered 11 other pulsars with no clear sign of periodic modulation. The 0.5-8 keV X-ray luminosity (L X ) of the pulsars ranges from 1034 to 1037 erg s-1 at 60 kpc. All of the Chandra sources with L X ? 4 × 1035 erg s-1 exhibit X-ray pulsations. The X-ray spectra of the SMC pulsars (and high-mass X-ray binaries) are in general harder than those of the SMC field population. All but SXP 8.02 can be fitted by an absorbed power-law model with a photon index of ? ? 1.5. The X-ray spectrum of the known magnetar SXP 8.02 is better fitted with a two-temperature blackbody model. Newly measured pulsation periods of SXP 51.0, SXP 214, and SXP 701, are significantly different from the previous XMM-Newton and RXTE measurements. This survey provides a rich data set for energy-dependent pulse profile modeling. Six pulsars show an almost eclipse-like dip in the pulse profile. Phase-resolved spectral analysis reveals diverse spectral variations during pulsation cycles: e.g., for an absorbed power-law model, some exhibit an (anti)-correlation between absorption and X-ray flux, while others show more intrinsic spectral variation (I.e., changes in photon indices).
SXP 214: An X-Ray Pulsar in the Small Magellanic Cloud, Crossing the Circumstellar Disk of the CompanionHong, JaesubAntoniou, ValliaZezas, AndreasHaberl, FrankDrake, Jeremy J.Plucinsky, Paul P.Gaetz, TerranceSasaki, ManamiWilliams, BenjaminLong, Knox S.Blair, William P.Winkler, P. FrankWright, Nicholas J.Laycock, SilasUdalski, AndrzejDOI: info:10.3847/0004-637X/826/1/4v. 8264
Hong, Jaesub, Antoniou, Vallia, Zezas, Andreas, Haberl, Frank, Drake, Jeremy J., Plucinsky, Paul P., Gaetz, Terrance, Sasaki, Manami, Williams, Benjamin, Long, Knox S., Blair, William P., Winkler, P. Frank, Wright, Nicholas J., Laycock, Silas, and Udalski, Andrzej. 2016. "SXP 214: An X-Ray Pulsar in the Small Magellanic Cloud, Crossing the Circumstellar Disk of the Companion." The Astrophysical Journal 826:4.
ID: 140229
Type: article
Authors: Hong, Jaesub; Antoniou, Vallia; Zezas, Andreas; Haberl, Frank; Drake, Jeremy J.; Plucinsky, Paul P.; Gaetz, Terrance; Sasaki, Manami; Williams, Benjamin; Long, Knox S.; Blair, William P.; Winkler, P. Frank; Wright, Nicholas J.; Laycock, Silas; Udalski, Andrzej
Abstract: Located in the Small Magellanic Cloud (SMC), SXP 214 is an X-ray pulsar in a high mass X-ray binary system with a Be-star companion. A recent survey of the SMC under a Chandra X-ray Visionary program found that the source was in a transition when the X-ray flux was on a steady rise. The Lomb-Scargle periodogram revealed a pulse period of 211.49 ± 0.42 s, which is significantly (>5?) shorter than the previous measurements made with XMM-Newton and RXTE. This implies that the system has gone through sudden spin-up episodes recently. The pulse profile shows a sharp eclipse-like feature with a modulation amplitude of >95%. The linear rise of the observed X-ray luminosity from ?2× to 7× {10}35 erg s-1 is correlated with a steady softening of the X-ray spectrum, which can be described by the changes in the local absorption from N H ~ 1024 to ?1020 cm-2 for an absorbed power-law model. The soft X-ray emission below 2 keV was absent in the early part of the observation when only the pulsating hard X-ray component was observed, whereas at later times, both soft and hard X-ray components were observed to be pulsating. A likely explanation is that the neutron star was initially hidden in the circumstellar disk of the companion, and later came out of the disk with the accreted material that continued fueling the observed pulsation.
Chasing the Identification of ASCA Galactic Objects (ChIcAGO): An X-Ray Survey of Unidentified Sources in the Galactic Plane. I. Source Sample and Initial ResultsAnderson, Gemma E.Gaensler, B. M.Kaplan, David L.Slane, Patrick O.Muno, Michael P.Posselt, BettinaHong, JaesubMurray, Stephen S.Steeghs, Danny T. H.Brogan, Crystal L.Drake, Jeremy J.Farrell, Sean A.Benjamin, Robert A.Chakrabarty, DeeptoDrew, Janet E.Finley, John P.Grindlay, Jonathan E.Lazio, T. Joseph W.Lee, Julia C.Mauerhan, Jon C.van Kerkwijk, Marten H.DOI: info:10.1088/0067-0049/212/1/13v. 21213
Anderson, Gemma E., Gaensler, B. M., Kaplan, David L., Slane, Patrick O., Muno, Michael P., Posselt, Bettina, Hong, Jaesub, Murray, Stephen S., Steeghs, Danny T. H., Brogan, Crystal L., Drake, Jeremy J., Farrell, Sean A., Benjamin, Robert A., Chakrabarty, Deepto, Drew, Janet E., Finley, John P., Grindlay, Jonathan E., Lazio, T. Joseph W., Lee, Julia C., Mauerhan, Jon C., and van Kerkwijk, Marten H. 2014. "Chasing the Identification of ASCA Galactic Objects (ChIcAGO): An X-Ray Survey of Unidentified Sources in the Galactic Plane. I. Source Sample and Initial Results." The Astrophysical Journal Supplement Series 212:13.
ID: 123004
Type: article
Authors: Anderson, Gemma E.; Gaensler, B. M.; Kaplan, David L.; Slane, Patrick O.; Muno, Michael P.; Posselt, Bettina; Hong, Jaesub; Murray, Stephen S.; Steeghs, Danny T. H.; Brogan, Crystal L.; Drake, Jeremy J.; Farrell, Sean A.; Benjamin, Robert A.; Chakrabarty, Deepto; Drew, Janet E.; Finley, John P.; Grindlay, Jonathan E.; Lazio, T. Joseph W.; Lee, Julia C.; Mauerhan, Jon C.; van Kerkwijk, Marten H.
Abstract: We present the Chasing the Identification of ASCA Galactic Objects (ChIcAGO) survey, which is designed to identify the unknown X-ray sources discovered during the ASCA Galactic Plane Survey (AGPS). Little is known about most of the AGPS sources, especially those that emit primarily in hard X-rays (2-10 keV) within the Fx ~ 10-13 to 10-11 erg cm-2 s-1 X-ray flux range. In ChIcAGO, the subarcsecond localization capabilities of Chandra have been combined with a detailed multiwavelength follow-up program, with the ultimate goal of classifying the >100 unidentified sources in the AGPS. Overall to date, 93 unidentified AGPS sources have been observed with Chandra as part of the ChIcAGO survey. A total of 253 X-ray point sources have been detected in these Chandra observations within 3' of the original ASCA positions. We have identified infrared and optical counterparts to the majority of these sources, using both new observations and catalogs from existing Galactic plane surveys. X-ray and infrared population statistics for the X-ray point sources detected in the Chandra observations reveal that the primary populations of Galactic plane X-ray sources that emit in the Fx ~ 10-13 to 10-11 erg cm-2 s-1 flux range are active stellar coronae, massive stars with strong stellar winds that are possibly in colliding wind binaries, X-ray binaries, and magnetars. There is also another primary population that is still unidentified but, on the basis of its X-ray and infrared properties, likely comprises partly Galactic sources and partly active galactic nuclei.
Multi-wavelength Observations of the Radio Magnetar PSR J1622–4950 and Discovery of Its Possibly Associated Supernova RemnantAnderson, Gemma E.Gaensler, B. M.Slane, Patrick O.Rea, NandaKaplan, David L.Posselt, BettinaLevin, LinaJohnston, SimonMurray, Stephen S.Brogan, Crystal L.Bailes, MatthewBates, SamuelBenjamin, Robert A.Bhat, N. D. R.Burgay, MartaBurke-Spolaor, SarahChakrabarty, DeeptoD'Amico, NichiDrake, Jeremy J.Esposito, PaoloGrindlay, Jonathan E.Hong, JaesubIsrael, G. L.Keith, Michael J.Kramer, MichaelLazio, T. J.Lee, Julia C.Mauerhan, Jon C.Milia, SabrinaPossenti, AndreaStappers, BenSteeghs, Danny T. H.DOI: info:10.1088/0004-637X/751/1/53v. 75153
Anderson, Gemma E., Gaensler, B. M., Slane, Patrick O., Rea, Nanda, Kaplan, David L., Posselt, Bettina, Levin, Lina, Johnston, Simon, Murray, Stephen S., Brogan, Crystal L., Bailes, Matthew, Bates, Samuel, Benjamin, Robert A., Bhat, N. D. R., Burgay, Marta, Burke-Spolaor, Sarah, Chakrabarty, Deepto, D'Amico, Nichi, Drake, Jeremy J., Esposito, Paolo, Grindlay, Jonathan E., Hong, Jaesub, Israel, G. L., Keith, Michael J., Kramer, Michael et al. 2012. "Multi-wavelength Observations of the Radio Magnetar PSR J1622–4950 and Discovery of Its Possibly Associated Supernova Remnant." The Astrophysical Journal 751:53.
ID: 111681
Type: article
Authors: Anderson, Gemma E.; Gaensler, B. M.; Slane, Patrick O.; Rea, Nanda; Kaplan, David L.; Posselt, Bettina; Levin, Lina; Johnston, Simon; Murray, Stephen S.; Brogan, Crystal L.; Bailes, Matthew; Bates, Samuel; Benjamin, Robert A.; Bhat, N. D. R.; Burgay, Marta; Burke-Spolaor, Sarah; Chakrabarty, Deepto; D'Amico, Nichi; Drake, Jeremy J.; Esposito, Paolo; Grindlay, Jonathan E.; Hong, Jaesub; Israel, G. L.; Keith, Michael J.; Kramer, Michael; Lazio, T. J.; Lee, Julia C.; Mauerhan, Jon C.; Milia, Sabrina; Possenti, Andrea; Stappers, Ben; Steeghs, Danny T. H.
Abstract: We present multi-wavelength observations of the radio magnetar PSR J1622-4950 and its environment. Observations of PSR J1622-4950 with Chandra (in 2007 and 2009) and XMM (in 2011) show that the X-ray flux of PSR J1622-4950 has decreased by a factor of ~50 over 3.7 years, decaying exponentially with a characteristic time of t = 360 ± 11 days. This behavior identifies PSR J1622-4950 as a possible addition to the small class of transient magnetars. The X-ray decay likely indicates that PSR J1622-4950 is recovering from an X-ray outburst that occurred earlier in 2007, before the 2007 Chandra observations. Observations with the Australia Telescope Compact Array show strong radio variability, including a possible radio flaring event at least one and a half years after the 2007 X-ray outburst that may be a direct result of this X-ray event. Radio observations with the Molonglo Observatory Synthesis Telescope reveal that PSR J1622-4950 is 8' southeast of a diffuse radio arc, G333.9+0.0, which appears non-thermal in nature and which could possibly be a previously undiscovered supernova remnant (SNR). If G333.9+0.0 is an SNR then the estimates of its size and age, combined with the close proximity and reasonable implied velocity of PSR J1622-4950, suggest that these two objects could be physically associated.
Discovery of a Significant Magnetic Cataclysmic Variable Population in the Limiting WindowHong, Jaesubvan den Berg, MaureenGrindlay, Jonathan E.Servillat, MathieuZhao, PingDOI: info:10.1088/0004-637X/746/2/165v. 746No. 2
Hong, Jaesub, van den Berg, Maureen, Grindlay, Jonathan E., Servillat, Mathieu, and Zhao, Ping. 2012. "Discovery of a Significant Magnetic Cataclysmic Variable Population in the Limiting Window." The Astrophysical Journal 746 (2):
ID: 110267
Type: article
Authors: Hong, Jaesub; van den Berg, Maureen; Grindlay, Jonathan E.; Servillat, Mathieu; Zhao, Ping
Abstract: We have discovered 10 periodic X-ray sources from the 1 Ms Chandra ACIS observation of the Limiting Window (LW), a low-extinction region (AV ~ 3.9) at 1fdg4 south of the Galactic center. The observed periods (~1.3-3.4 hr) and the X-ray luminosities (1031.8-32.9 erg s–1 at 8 kpc) of the 10 periodic sources, combined with the lack of bright optical counterparts and thus high X-ray-to-optical flux ratios, suggest that they are likely accreting binaries, in particular, magnetic cataclysmic variables (MCVs). All of them exhibit a relatively hard X-ray spectrum (? < 2 for a power-law model), and relatively high extinction observed
The ChaMPlane Bright X-Ray Sources-Galactic Longitudes l = 2°-358°van den Berg, MaureenPenner, KyleHong, JaesubGrindlay, Jonathan E.Zhao, PingLaycock, SilasServillat, MathieuDOI: info:10.1088/0004-637X/748/1/31v. 74831
van den Berg, Maureen, Penner, Kyle, Hong, Jaesub, Grindlay, Jonathan E., Zhao, Ping, Laycock, Silas, and Servillat, Mathieu. 2012. "The ChaMPlane Bright X-Ray Sources-Galactic Longitudes l = 2°-358°." The Astrophysical Journal 748:31.
ID: 110770
Type: article
Authors: van den Berg, Maureen; Penner, Kyle; Hong, Jaesub; Grindlay, Jonathan E.; Zhao, Ping; Laycock, Silas; Servillat, Mathieu
Abstract: The Chandra Multi-wavelength Plane (ChaMPlane) survey aims to constrain the Galactic population of mainly accretion-powered, but also coronal, low-luminosity X-ray sources (L X 33 erg s-1). To investigate the X-ray source content in the plane at fluxes F X >~ 3 × 10-14 erg s-1 cm-2, we study 21 of the brightest ChaMPlane sources, viz., those with >250 net counts (0.3-8 keV). By excluding the heavily obscured central part of the plane, our optical/near-infrared follow-up puts useful constraints on their nature.