Article
Astronomy & Astrophysics
Yuri Cavecchi, Alessandro Patruno
Summary: Research confirms that burst oscillations of AMXP XTE J1814-338 are phase-locked to accretion-powered pulsations during thermonuclear bursts, with moderate drifts observed. This phenomenon could provide important constraints on the thermonuclear burst mechanism.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ashwin Devaraj, Biswajit Paul
Summary: We report the results of a timing and spectral analysis of the Be/X-ray binary, XTE J1946 + 274, which underwent a Type II outburst. We detected a cyclotron line and observed energy dependence in the pulse profile. Compilation of previous literature suggests that this source has been observed over a wide range of fluxes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
V Sguera, L. Sidoli, A. J. Bird, N. La Palombara
Summary: We present new results from INTEGRAL and Swift observations of the poorly studied and unidentified X-ray source XTE J1906+090. A bright hard X-ray outburst has been detected, as well as consistent low X-ray luminosity values. Based on our findings, we propose that XTE J1906+090 belongs to the small and rare group of persistent low-luminosity Be X-ray binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Varun Varun, Gayathri Raman
Summary: We conducted a comprehensive study of two high mass X-ray binary sources using NuSTAR observations. The sources, IGR J16320-4751 and IGR J16479-4514, were characterized for the first time in the hard X-ray band. Intense X-ray flares were observed in both sources, with average luminosities exceeding 10(36) erg/s. The flares were found to occur during the periastron passage of the neutron star, rather than due to the presence of a corotating interaction region. The pulse fraction was lower in hard X-rays compared to soft X-rays in IGR J16320-4751. Spectral parameters and surface magnetic field strength estimates were provided for both sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alexander Salganik, Sergey S. Tsygankov, Anlaug A. Djupvik, Dmitri I. Karasev, Alexander A. Lutovinov, David A. H. Buckley, Mariusz Gromadzki, Juri Poutanen
Summary: This study focuses on the spectral and timing properties of the poorly studied X-ray pulsar XTE J1859+083 during its 2015 outburst. The source pulse profile was found to have a complex shape depending on the energy band, and the pulse fraction remained constant around 35% in the broad energy band, which is atypical for X-ray pulsars. The optical and infrared observations revealed that the system is a Be X-ray binary.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ruican Ma, Lian Tao, Shuang-Nan Zhang, Long Ji, Liang Zhang, Qingcui Bu, Jinlu Qu, Pablo Reig, Mariano Mendez, Yanan Wang, Xiang Ma, Yue Huang, Mingyu Ge, Liming Song, Shu Zhang, Hexin Liu, Pengju Wang, Lingda Kong, Xiaoqin Ren, Shujie Zhao, Wei Yu, Zixu Yang, Panping Li, Shumei Jia
Summary: In this study, we investigated the millihertz quasi-periodic oscillation (mHz QPO) in the 2020 outburst of the Be/X-ray binary 1A 0535 + 262 using Insight-HXMT data. The mHz QPO was detected in the energy range of 27-120 keV and showed a correlation with the source flux. The most significant QPO signal was observed in the 50-65 keV energy band, reaching a significance level of approximately 8 sigma. Interestingly, this study also detected mHz QPO above 80 keV, which is the highest energy at which such oscillations have been observed so far.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Chetana Jain, Rahul Sharma, Biswajit Paul
Summary: We present an updated measurement of the orbital period evolution of LMXB XTE J1710-281 using the eclipse timing technique. Our findings include the discovery of a third orbital period glitch and the detection of four distinct epochs of orbital period in this system. We also provide a more robust estimation of the second orbital period glitch. The implications of our findings for the magnetic nature of the companion star and possible scattering events are discussed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. A. Mushtukov, S. S. Tsygankov, J. Poutanen, V. Doroshenko, A. Salganik, E. Costa, A. Di Marco, J. Heyl, F. La Monaca, A. A. Lutovinov, I. A. Mereminsky, A. Papitto, A. N. Semena, A. E. Shtykovsky, V. F. Suleimanov, S. V. Forsblom, D. Gonzalez-Caniulef, C. Malacaria, R. A. Sunyaev, I. Agudo, L. A. Antonelli, M. Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, C. -T. Chen, S. Ciprini, A. De Rosa, E. Del Monte, L. Di Gesu, N. Di Lalla, I. Donnarumma, M. Dovciak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia, S. Gunji, K. Hayashida, W. Iwakiri, S. G. Jorstad, P. Kaaret, V. Karas, F. Kislat, T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski, L. Latronico, I. Liodakis, S. Maldera, A. Manfreda, F. Marin, A. P. Marscher, H. L. Marshall, F. Massaro, G. Matt, I. Mitsuishi, T. Mizuno, F. Muleri, M. Negro, C. -Y. Ng, S. L. O'Dell, N. Omodei, C. Oppedisano, G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce-Rollins, P. -O. Petrucci, M. Pilia, A. Possenti, S. Puccetti, B. D. Ramsey, J. Rankin, A. Ratheesh, O. J. Roberts, R. W. Romani, C. Sgro, P. . Slane, P. . Soffitta, G. Spandre, D. A. Swartz, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois, R. Turolla, J. Vink, M. C. Weisskopf, K. Wu, F. Xie, S. Zane
Summary: X Persei is a highly magnetized X-ray pulsar with a low luminosity and a period of 835 seconds. Observations with the IXPE revealed a strong dependency of the X-ray polarization signal on the pulsar's spin phase. The polarization degree varied from several to approximately 20% over the pulse, with a phase dependence resembling the pulse profile. The polarimetric data also implied a large angle between the rotation and magnetic dipole axes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Federico A. Fogantini, Federico Garcia, Jorge A. Combi, Sylvain Chaty
Summary: The study aims to investigate the geometrical and physical properties of stellar wind structures formed by the interaction between the compact object and the supergiant star. The XMM-Newton light curves show that the source hardens during the eclipse, and a reduced pulse modulation is observed on the ingress to the eclipse. By analyzing the spectral analysis, a scenario is proposed where a photo-ionization wake and an accretion wake are responsible for the absorption column, continuum emission, and variability seen at the Fe-line complex.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. M. Chen, J. Takata
Summary: Our study focuses on the wind interactions and shock radiations in Be/gamma-ray binaries, showing that the bimodal structures observed in keV/TeV light curves are caused by enhanced synchrotron radiation and IC scattering during disc passages. We use a radiation model to reproduce orbital modulations and compare with confirmed binaries, finding that the former two can be well explained while the latter two remain challenging. We propose alternative orbital geometries for the latter two sources and estimate the positions and inclination angles of Be discs. Our results could benefit future measurements and searches for radio pulsations.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
G. Sanjurjo-Ferrin, J. M. Torrejon, J. J. Rodes-Roca
Summary: We present the first XMM-Newton observation of the classical supergiant high-mass X-ray binary XTE J1855-026 taken entirely during the eclipse of the neutron star (NS). By analyzing the data, we compare the parameters obtained during pre-eclipse observation and explore the back-illuminated stellar wind of the B0I-type donor. We find that the blackbody component, used to describe the soft excess during pre-eclipse, is not observed during eclipse, and the Fe K alpha line intensity and the 0.3-10 keV luminosity during eclipse are significantly lower than during pre-eclipse. The eclipse spectrum can be successfully modeled by adding two photoionized plasmas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
I. M. Monageng, M. J. Coe, L. J. Townsend, S. G. T. Laycock, J. A. Kennea, A. Roy, A. Udalski, S. Bhattacharya, D. M. Christodoulou, D. A. H. Buckley, P. A. Evans
Summary: This study presents the results of the investigation of two Be X-ray binaries, SXP 15.3 and SXP 305, in the Small Magellanic Cloud. Through long-term optical and X-ray monitoring, the historic and recent behavior of these sources were studied. It was found that the X-ray emission likely comes from SXP 15.3, and the optical outbursts show modulation at approximately twice the frequency of the X-ray outbursts. Models based on the geometric orientations of the Be disc and neutron star were proposed to explain the physical origin of the outbursts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Valentina Peirano, Mariano Mendez
Summary: We analyzed 14 observations of the neutron star X-ray binary XTE J1701-462 and found differences in time lags between atoll and Z-phase observations of the kHz QPOs. We suggest that these differences may be related to a Comptonizing component or an oscillation of the corona coupled with the innermost regions of the accretion disk.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
K. Anastasopoulou, A. Zezas, J. F. Steiner, P. Reig
Summary: This paper uses spectral models from X-ray binaries and ultra-luminous X-ray sources to analyze the behavior of accretion flow and the contribution of the disc to optical emission in binary systems. The research provides valuable insights for understanding the energetics and nature of X-ray binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Alexander Salganik, Sergey S. Tsygankov, Alexander A. Lutovinov, Anlaug A. Djupvik, Dmitri Karasev, Sergey Molkov
Summary: This study investigates the temporal and spectral properties of the poorly studied X-ray pulsar Swift J1808.4-1754. The results reveal strong pulsations with non-monotonic variation in the pulsed fraction along the energy range, with a local minimum around 17-22 keV. The study also discovers phase lags in the pulse profile components and analyzes the pulse phase-averaged spectrum.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
C. Malacaria, L. Ducci, M. Falanga, D. Altamirano, E. Bozzo, S. Guillot, G. K. Jaisawal, P. Kretschmar, M. Ng, P. Pradhan, R. Rothschild, A. Sanna, P. Thalhammer, J. Wilms
Summary: When X-ray pulsars accrete and undergo bright X-ray outbursts, their spectral and timing features can be analyzed. The X-ray pulsar GRO J1750-27 recently went through an outburst episode and was observed with NuSTAR and monitored with NICER. The analysis of the data revealed a highly absorbed spectrum with an iron line, a blackbody component from the accretion disk, and the discovery of a deep cyclotron line. The pulse profiles observed remained steady throughout the outburst, contrary to expectations and other similar sources.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Giulia Illiano, Alessandro Papitto, Andrea Sanna, Peter Bult, Filippo Ambrosino, Arianna Miraval Zanon, Francesco Coti Zelati, Luigi Stella, Diego Altamirano, Maria Cristina Baglio, Enrico Bozzo, Luciano Burderi, Domitilla de Martino, Alessandro Di Marco, Tiziana di Salvo, Carlo Ferrigno, Vladislav Loktev, Alessio Marino, Mason Ng, Maura Pilia, Juri Poutanen, Tuomo Salmi
Summary: We analyzed NICER observations of SAX J1808.4-3658 and found similar behavior as previous outbursts. After peaking at a luminosity of about 1 x 10^36 erg/s, the pulsar entered a month-long reflaring stage. The average pulsar spin frequency during the outburst was confirmed to match previous measurements, indicating a long-term spin derivative and a rotating magnetic dipole. Furthermore, for the first time in twenty years, the orbital phase evolution showed evidence of a decreasing orbital period, which is influenced by a modulation with a period of approximately 21 years.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
A. Manca, A. F. Gambino, A. Sanna, G. K. Jaisawal, T. Di Salvo, R. Iaria, S. M. Mazzola, A. Marino, A. Anitra, E. Bozzo, A. Riggio, L. Burderi
Summary: The study focuses on the Accreting Millisecond X-ray Pulsar IGR J17591-2342, a Low Mass X-ray Binary (LMXB) system that experienced an outburst in August 2018. By analyzing the X-ray data from multiple observations, the researchers investigated the evolution of the spectral emission during the outburst. The findings suggest the presence of an absorbed Comptonization component with a temperature of 34 keV and a moderately optically thick corona. In addition, a blackbody component and absorption edge of O viii, as well as emission lines of Ne ix ions, were detected in some spectra, indicating possible reflection in the system.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Rahul Sharma, Andrea Sanna, Aru Beri
Summary: We analyzed the data set of the accreting millisecond X-ray pulsar SAX J1808.4-3658 obtained during its 2019 outburst using AstroSat. The pulsar showed coherent pulsations at around 401 Hz and had a consistent orbital solution with previous studies. The pulse profile in the 3-20 keV energy range could be well fitted with three harmonically related sinusoidal components, and the energy-resolved pulse profile evolution study indicated a strong energy dependence. The broad-band spectrum of SAX J1808.4-3658 could be described by a combination of thermal emission, thermal Comptonization from the hot corona, and broad emission lines due to Fe.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
G. K. Jaisawal, G. Vasilopoulos, S. Naik, C. Maitra, C. Malacaria, B. Chhotaray, K. C. Gendreau, S. Guillot, M. Ng, A. Sanna
Summary: We present the spectral and temporal properties of the Be/X-ray binary pulsar SMC X-2 based on X-ray observations during the 2015 and 2022 outbursts. The pulse profile of the pulsar is luminosity dependent, transitioning from a broad-humped to a double-peaked profile above a certain luminosity. The pulse fraction and energy of the pulsar show a linear correlation. In addition, we observe spectral evolution during the latest outburst, suggesting a transition from sub-critical to supercritical regime.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. C. Albayati, P. Bult, D. Altamirano, J. Chenevez, S. Guillot, T. Guever, G. K. Jaisawal, C. Malacaria, G. C. Mancuso, A. Marino, M. Ng, A. Sanna, T. E. Strohmayer
Summary: This paper reports on observations made by NICER of seven thermonuclear X-ray bursts from Swift J1749.4-2807 during its 2021 outburst. The bursts show different characteristics, with the first six indicating the presence of mixed H/He fuel and the last burst suggesting He-rich fuel. Time-resolved spectroscopy revealed an increase in blackbody temperature during the burst rise and a steady decrease in the decay. The observed change in absorption is interpreted as evidence of burst-disc interaction, due to the high inclination of the system. Additionally, burst oscillations at the known spin frequency of the neutron star were detected for the first time in Swift J1749.4-2807.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Del Santo, C. Pinto, A. Marino, A. D'Ai, P-O Petrucci, J. Malzac, J. Ferreira, F. Pintore, S. E. Motta, T. D. Russell, A. Segreto, A. Sanna
Summary: The transient X-ray source MAXI J1810-222, discovered in 2018, has shown continuous activity since then. A radio and X-ray monitoring campaign was conducted with the Australia Telescope Compact Array and Swift, respectively. The source is believed to be a distant black hole X-ray binary with peculiar outburst behavior. Spectral study using a large sample of NICER observations revealed a strong absorption feature at approximately 1 keV, characterized with a physical photoionization model. Evidence for a spectral-state dependent outflow with mildly relativistic speeds was obtained, suggesting that the outflows could be radiation pressure or magnetically driven winds. These results are crucial for testing theoretical models of wind formation in X-ray binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alessandro Di Marco, Fabio La Monaca, Juri Poutanen, Thomas Russell, Alessio Anitra, Ruben Farinelli, Guglielmo Mastroserio, Fabio Muleri, Fei Xie, Matteo Bachetti, Luciano Burderi, Francesco Carotenuto, Melania Del Santo, Tiziana Di Salvo, Michal Dovciak, Andrea Gnarini, Rosario Iaria, Jari J. E. Kajava, Kuan Liu, Riccardo L. Middei, Stephen O'Dell, Maura Pilia, John Rankin, Andrea Sanna, Jakob van den Eijnden, Martin C. Weisskopf, Anna Bobrikova, Fiamma Capitanio, Enrico Costa, Philip Kaaret, Alessio Marino, Paolo Soffitta, Francesco Ursini, Filippo Ambrosino, Massimo Cocchi, Sergio Fabiani, Herman Marshall, Giorgio Matt, Sara Elisa Motta, Alessandro Papitto, Luigi Stella, Antonella Tarana, Silvia Zane, Ivan Agudo, Lucio A. Antonelli, Luca H. Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolo Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolo Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao J. Kitaguchi, Jeffery Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frederic Marin, Andrea Marinucci, Alan P. Marscher, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Chi-Yung Ng, Nicola Omodei, Chiara G. Oppedisano, George L. Pavlov, Abel Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Simonetta D. Puccetti, Brian Ramsey, Ajay J. Ratheesh, Oliver W. Roberts, Roger Romani, Carmelo Sgro, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru F. Tawara, Allyn E. Tennant, Nicholas Thomas, Francesco Tombesi, Alessio Trois, Sergey Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu
Summary: This paper reports the first detection of polarization in the X-rays for atoll-source 4U 1820-303, obtained with the Imaging X-ray Polarimetry Explorer (IXPE) at a 99.999% confidence level. The source shows a significant polarization above 4 keV, with the polarization degree increasing with energy. The spectro-polarimetric fit indicates an orthogonal polarization direction between the hard spectral component and the accretion disk.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
A. Marino, T. D. Russell, M. Del Santo, A. Beri, A. Sanna, F. Coti Zelati, N. Degenaar, D. Altamirano, E. Ambrosi, A. Anitra, F. Carotenuto, A. D'Ai, T. Di Salvo, A. Manca, S. E. Motta, C. Pinto, F. Pintore, N. Rea, J. van den Eijnden
Summary: This paper presents the results of a multiwavelength observational campaign on the neutron star low-mass X-ray binary 4U 1820-30, showing that the X-ray flux modulation is mainly caused by changes in the size of the region providing seed photons for the Comptonization spectrum.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Anastasia Tsvetkova, Luciano Burderi, Alessandro Riggio, Andrea Sanna, Tiziana Di Salvo
Summary: According to Einstein's theory of relativity, the speed of light is constant in a vacuum. However, quantum gravity effects may cause dispersion in the speed of light depending on photon energy. Studying the spectral lags between gamma-ray burst (GRB) light curves recorded at different energy ranges can provide insights into this phenomenon, if the speed of light is linearly dependent on photon energy and a function of GRB redshift. We propose a methodology using GRB light curves to investigate the dispersion law of light propagation in a vacuum, with the intention of utilizing GRB data collected by THESEUS.