244 research outputs found
X-Ray Polarization of the Black Hole X-Ray Binary 4U 1630-47 Challenges the Standard Thin Accretion Disk Scenario
No full textRatheesh, Ajay et al.--Full list of authors: Ratheesh, Ajay; Dovčiak, Michal; Krawczynski, Henric; Podgorný, Jakub; Marra, Lorenzo; Veledina, Alexandra; Suleimanov, Valery F.; Rodriguez Cavero, Nicole; Steiner, James F.; Svoboda, Jiří; Marinucci, Andrea; Bianchi, Stefano; Negro, Michela; Matt, Giorgio; Tombesi, Francesco; Poutanen, Juri; Ingram, Adam; Taverna, Roberto; West, Andrew; Karas, Vladimir; Ursini, Francesco; Soffitta, Paolo; Capitanio, Fiamma; Viscolo, Domenico; Manfreda, Alberto; Muleri, Fabio; Parra, Maxime; Beheshtipour, Banafsheh; Chun, Sohee; Cibrario, Nicolò; Di Lalla, Niccolò; Fabiani, Sergio; Hu, Kun; Kaaret, Philip; Loktev, Vladislav; Mikušincová, Romana; Mizuno, Tsunefumi; Omodei, Nicola; Petrucci, Pierre-Olivier; Puccetti, Simonetta; Rankin, John; Zane, Silvia; Zhang, Sixuan; Agudo, Iván; Antonelli, Lucio A.; Bachetti, Matteo; Baldini, Luca; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolò; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chien-Ting; Ciprini, Stefano; Costa, Enrico; De Rosa, Alessandra; Del Monte, Ettore; Di Gesu, Laura; Di Marco, Alessandro; Donnarumma, Immacolata; Doroshenko, Victor; Ehlert, Steven R.; Enoto, Teruaki; Evangelista, Yuri; Ferrazzoli, Riccardo; Garcia, Javier A.; Gunji, Shuichi; Hayashida, Kiyoshi; Heyl, Jeremy; Iwakiri, Wataru; Jorstad, Svetlana G.; Kislat, Fabian; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; La Monaca, Fabio; Latronico, Luca; Liodakis, Ioannis; Maldera, Simone; Marin, Frédéric; Marscher, Alan P.; Marshall, Herman L.; Massaro, Francesco; Mitsuishi, Ikuyuki; Ng, Stephen C. -Y.; O'Dell, Stephen L.; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel L.; Perri, Matteo; Pesce-Rollins, Melissa; Pilia, Maura; Possenti, Andrea; Ramsey, Brian D.; Roberts, Oliver J.; Romani, Roger W.; Sgrò, Carmelo; Slane, Patrick; Spandre, Gloria; Swartz, Douglas A.; Tamagawa, Toru; Tavecchio, Fabrizio; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; Trois, Alessio; Tsygankov, Sergey S.; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C.; Wu, Kinwah; Xie, FeiA large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer (IXPE) in the high-soft emission state of the black hole X-ray binary 4U 1630–47. The highly significant detection (at ≈50σ confidence level) of an unexpectedly high polarization, rising from ∼6% at 2 keV to ∼10% at 8 keV, cannot be easily reconciled with standard models of thin accretion disks. In this work, we compare the predictions of different theoretical models with the IXPE data and conclude that the observed polarization properties are compatible with a scenario in which matter accretes onto the black hole through a thin disk covered by a partially ionized atmosphere flowing away at mildly relativistic velocities. © 2024. The Author(s). Published by the American Astronomical Society.The Imaging X-ray Polarimetry Explorer (IXPE) is a joint US and Italian mission. The US contribution is supported by the National Aeronautics and Space Administration (NASA) and led and managed by its Marshall Space Flight Center (MSFC), with industry partner Ball Aerospace (contract NNM15AA18C). The Italian contribution is supported by the Italian Space Agency (Agenzia Spaziale Italiana, ASI) through contract ASI-OHBI-2022-13-I.0, agreements ASI-INAF-2022-19-HH.0 and ASI-INFN-2017.13-H0, and its Space Science Data Center (SSDC) with agreements ASI-INAF-2022-14-HH.0 and ASI-INFN 2021-43-HH.0, and by the Istituto Nazionale di Astrofisica (INAF) and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. This research used data products provided by the IXPE Team (MSFC, SSDC, INAF, and INFN) and distributed with additional software tools by the High-Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC). M.D., J.Pod., J.S., and V.K. acknowledge the support from the Czech Science Foundation project GACR 21-06825X and the institutional support from the Astronomical Institute of the Czech Academy of Sciences RVO:67985815. J. Podgorný and V.K. thank the Czech-Polish mobility program (MŠMT 8J20PL037 and PPN/BCZ/2019/1/00069) and the European Space Agency PRODEX project 4000132152. M.D. and J. Podgorný especially thank Prof. Agata Różańska for explanations and guidance using the TITAN code. H.K., N.R.C., and A.W. acknowledge NASA support through grants NNX16AC42G, 80NSSC20K0329, 80NSSC20K0540, NAS8-03060, 80NSSC21K1817, 80NSSC22K1291, and 80NSSC22K1883 as well as support from the McDonnell Center for the Space Sciences. A.V., J.Pou., V.L., and S.S.T. acknowledge support from Academy of Finland grants 349144 and 355672. V.F.S. acknowledges Deutsche Forschungsgemeinschaft (DFG) support through grant WE 1312/59-1 and the German Academic Exchange Service (DAAD) support through project 57525212. A.I. acknowledges support from the Royal Society. The French collaborators acknowledge financial support from the French High Energy national program from CNRS and from the French Space Agency (CNES). M.N. acknowledges the support by NASA under award No. 80GSFC21M0002.Peer reviewe
Sub-MeV spectroscopy with AstroSat-CZT imager for gamma ray bursts
No full textCadmium–Zinc–Telluride Imager (CZTI) onboard AstroSat has been a prolific Gamma-Ray Burst (GRB) monitor. While the 2-pixel Compton scattered events (100–300 keV) are used to extract sensitive spectroscopic information, the inclusion of the low-gain pixels (∼ 20% of the detector plane) after careful calibration extends the energy range of Compton energy spectra to 600 keV. The new feature also allows single-pixel spectroscopy of the GRBs to the sub-MeV range which is otherwise limited to 150 keV. We also introduced a new noise rejection algorithm in the analysis (‘Compton noise’). These new additions not only enhances the spectroscopic sensitivity of CZTI, but the sub-MeV spectroscopy will also allow proper characterization of the GRBs not detected by Fermi. This article describes the methodology of single, Compton event and veto spectroscopy in 100–900 keV combined for the GRBs detected in the first year of operation. CZTI in last five years has detected ∼ 20 bright GRBs. The new methodologies, when applied on the spectral analysis for this large sample of GRBs, has the potential to improve the results significantly and help in better understanding the prompt emission mechanism
Polarization properties of X-ray tubes used for Imaging X-ray Polarimetry Explorer calibration
No full textHard X-Ray Polarization Catalog for a Five-year Sample of Gamma-Ray Bursts Using AstroSat CZT Imager
No full textThe Cadmium Zinc Telluride Imager (CZTI) on board AstroSat has been regularly detecting gamma-ray bursts (GRBs) since its launch in 2015. Its sensitivity to polarization measurements at energies above 100 keV allows CZTI to attempt spectropolarimetric studies of GRBs. Here, we present the first catalog of GRB polarization measurements made by CZTI during its first five years of operation. This includes the time-integrated polarization measurements of the prompt emission of 20 GRBs in the energy range 100-600 keV. The sample includes the bright GRBs that were detected within an angle range of 0 degrees-60 degrees and 120 degrees-180 degrees where the instrument has useful polarization sensitivity and is less prone to systematics. We implement a few new modifications in the analysis to enhance the polarimetric sensitivity of the instrument. The majority of the GRBs in the sample are found to possess less/null polarization across the total bursts' duration in contrast to a small fraction of five GRBs that exhibit high polarization. The low polarization across the bursts might be due either to the burst being intrinsically weakly polarized or to a varying polarization angle within the burst even when it is highly polarized. In comparison to POLAR measurements, CZTI has detected a larger number of cases with high polarization. This may be a consequence of the higher energy window of CZTI observations, which results in the sampling of a shorter duration of burst emissions than POLAR, thereby probing emissions with less temporal variation in polarization properties
X-Ray Polarization of the Black Hole X-Ray Binary 4U 1630-47 Challenges the Standard Thin Accretion Disk Scenario
No full textA large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer (IXPE) in the high-soft emission state of the black hole X-ray binary 4U 1630-47. The highly significant detection (at approximate to 50 sigma confidence level) of an unexpectedly high polarization, rising from similar to 6% at 2 keV to similar to 10% at 8 keV, cannot be easily reconciled with standard models of thin accretion disks. In this work, we compare the predictions of different theoretical models with the IXPE data and conclude that the observed polarization properties are compatible with a scenario in which matter accretes onto the black hole through a thin disk covered by a partially ionized atmosphere flowing away at mildly relativistic velocities.</p
Universality of coronal properties in accreting black holes across mass and accretion rate
No full textThrough their radio loudness, lack of thermal UV emission from the accretion
disk and power-law dominated spectra, Low Luminosity AGN (LLAGN) display
similarity with the hard state of stellar-mass black hole X-Ray Binaries
(BHBs). In this work we perform a systematic hard X-ray spectral study of a
carefully selected sample of unobscured LLAGN using archival data, to
understand the central engine properties in the lower accretion regime. We
analyze the spectra of a sample of 16 LLAGN. We model the continuum
emission with detailed Comptonization models. We find a strong anti-correlation
between the optical depth and the electron temperature of the corona,
previously also observed in the brighter Seyferts. This anti-correlation is
present irrespective of the shape of the corona, and the slope of this
anti-correlation in the log space for LLAGN (0.68-1.06) closely matches that of
the higher accretion rate Seyferts (0.55-1.11) and hard state of BHBs
(0.87). This anti-correlation may indicate a departure from a fixed
disk-corona configuration in radiative balance. Our result, therefore,
demonstrates a possible universality in Comptonization processes of black hole
X-ray sources across multiple orders of magnitude in mass and accretion rate.Comment: 9 pages, 3 figures. Shortened abstract. Accepted for publication in
A&A Letter
Polarization Properties of the Weakly Magnetized Neutron Star X-Ray Binary GS 1826–238 in the High Soft State
No full textCapitanio, Fiamma et al.--Full list of authors: Capitanio, Fiamma; Fabiani, Sergio; Gnarini, Andrea; Ursini, Francesco; Ferrigno, Carlo; Matt, Giorgio; Poutanen, Juri; Cocchi, Massimo; Mikusincova, Romana; Farinelli, Ruben; Bianchi, Stefano; Kajava, Jari J. E.; Muleri, Fabio; Sanchez-Fernandez, Celia; Soffitta, Paolo; Wu, Kinwah; Agudo, Ivan; Antonelli, Lucio A.; Bachetti, Matteo; Baldini, Luca; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolo; Castellano, Simone; Cavazzuti, Elisabetta; Ciprini, Stefano; Costa, Enrico; De Rosa, Alessandra; Del Monte, Ettore; Di Gesu, Laura; Di Lalla, Niccolo; Di Marco, Alessandro; Donnarumma, Immacolata; Doroshenko, Victor; Dovciak, Michal; Ehlert, Steven R.; Enoto, Teruaki; Evangelista, Yuri; Ferrazzoli, Riccardo; Garcia, Javier A.; Gunji, Shuichi; Hayashida, Kiyoshi; Heyl, Jeremy; Iwakiri, Wataru; Jorstad, Svetlana G.; Karas, Vladimir; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; Krawczynski, Henric; La Monaca, Fabio; Latronico, Luca; Liodakis, Ioannis; Maldera, Simone; Manfreda, Alberto; Marin, Frederic; Marinucci, Andrea; Marscher, Alan P.; Marshall, Herman L.; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; Ng, C. -Y.; O'Dell, Stephen L.; Omodei, Nicola; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel L.; Perri, Matteo; Pesce-Rollins, Melissa; Petrucci, Pierre-Olivier; Pilia, Maura; Possenti, Andrea; Puccetti, Simonetta; Ramsey, Brian D.; Rankin, John; Ratheesh, Ajay; Romani, Roger W.; Sgro, Carmelo; Slane, Patrick; Spandre, Gloria; Tamagawa, Toru; Tavecchio, Fabrizio; Taverna, Roberto; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; Tombesi, Francesco; Trois, Alessio; Tsygankov, Sergey S.; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C.; Xie, Fei; Zane, SilviaThe launch of the Imaging X-ray Polarimetry Explorer (IXPE) on 2021 December 9 has opened a new window in X-ray astronomy. We report here the results of the first IXPE observation of a weakly magnetized neutron star, GS 1826−238, performed on 2022 March 29–31 when the source was in a high soft state. An upper limit (99.73% confidence level) of 1.3% for the linear polarization degree is obtained over the IXPE 2–8 keV energy range. Coordinated INTEGRAL and NICER observations were carried out simultaneously with IXPE. The spectral parameters obtained from the fits to the broadband spectrum were used as inputs for Monte Carlo simulations considering different possible geometries of the X-ray emitting region. Comparing the IXPE upper limit with these simulations, we can put constraints on the geometry and inclination angle of GS 1826–238. © 2023. The Author(s). Published by the American Astronomical Society.J.P. and S.S.T. acknowledge support from Russian Science Foundation grant 20-12-00364 and Academy of Finland travel grants 349144, 349373, and 349906. J.P. and J.J.E.K. were supported by Academy of Finland grant 333112.Peer reviewe
In-flight calibration system of imaging x-ray polarimetry explorer
No full textThe NASA/ASI Imaging X-ray Polarimetry Explorer, which will be launched in 2021, will be the first instrument to perform spatially resolved X-ray polarimetry on several astronomical sources in the 2-8 keV energy band. These measurements are made possible owing to the use of a gas pixel detector (GPD) at the focus of three X-ray telescopes. The GPD allows simultaneous measurements of the interaction point, energy, arrival time, and polarization angle of detected X-ray photons. The increase in sensitivity, achieved 40 years ago, for imaging and spectroscopy with the Einstein satellite will thus be extended to X-ray polarimetry for the first time. The characteristics of gas multiplication detectors are subject to changes over time. Because the GPD is a novel instrument, it is particularly important to verify its performance and stability during its mission lifetime. For this purpose, the spacecraft hosts a filter and calibration set (FCS), which includes both polarized and unpolarized calibration sources for performing in-flight calibration of the instruments. In this study, we present the design of the flight models of the FCS and the first measurements obtained using silicon drift detectors and CCD cameras, as well as those obtained in thermal vacuum with the flight units of the GPD. We show that the calibration sources successfully assess and verify the functionality of the GPD and validate its scientific results in orbit; this improves our knowledge of the behavior of these detectors in X-ray polarimetry
IXPE DU-FM ions-UV filters characterization
No full textIXPE (Imaging X-ray Polarimetry Explorer) is a NASA SMEX in a partnership with ASI. The focal plane Detector Units (DUs) and the Detector Service Unit (DSU) were developed by the Italian research Institutes INAF-IAPS and INFN and were manufactured by OHB-I. IXPE will investigate X-ray polarimetry in the 2-8 keV energy band. The payload comprises three identical telescopes, each composed of a mirror and a detector unit with an X-ray polarimeter based on the Gas Pixel Detector (GPD). A stray-light collimator (SLC) is mounted on the top of the DU to shield the GPD from background X-rays not coming from the optics. At the bottom of the SLC, an ions-UV filter is mounted to reduce the thermal load and to prevent ions and UV from entering the DU. The ions-UV filters consist mainly of 1 um LUXFilm (based on polyimide). During on-ground calibration activities of the IXPE DUs, X-ray transparency of DU-FM ions-UV filters was measured with monochromatic X-ray at 2.7 keV and 6.4 keV at INAF-IAPS
The Imaging X-ray Polarimetry Explorer (IXPE) at last!
No full textFull list of the authors: Soffitta, Paolo; Baldini, Luca; Baumgartner, Wayne; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bucciantini, Niccolò; Costa, Enrico; Dovčiak, Michal; Ehlert, Steven; Kaaret, Philip E.; Kolodziejczak, Jeffery J.; Latronico, Luca; Marin, Frédéric; Marscher, Alan P.; Marshall, Herman L.; Matt, Giorgio; Muleri, Fabio; O'Dell, Stephen L.; Poutanen, Juri; Ramsey, Brian; Romani, Roger W.; Slane, Patrick; Tennant, Allyn F.; Turolla, Roberto; Weisskopf, Martin C.; Agudo, Iván.; Antonelli, Lucio Angelo; Bachetti, Matteo; Bianchi, Stefano; Bonino, Raffaella; Brez, Alessandro; Capitanio, Fiamma; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chiel-Ting; Ciprini, Stefano; De Rosa, Alessandra; Del Monte, Ettore; Di Gesu, Laura; Di Lalla, Niccolò; Di Marco, Alessandro; Donnarumma, Immacolata; Doroshenko, Victor; Enoto, Teruaki; Evangelista, Yuri; Fabiani, Sergio; Ferrazzoli, Riccardo; Garcia, Javier A.; Gunji, Shuichi; Hayashida, Kiyoshi; Heyl, Jeremy; Iwakiri, Wataru; Jorstad, Svetlana G.; Karas, Vladimir; Kislat, Fabian; Kitaguchi, Takao; Krawczynski, Henric; La Monaca, Fabio; Liodakis, Ioannis; Maldera, Simone; Manfreda, Alberto; Marinucci, Andrea; Massaro, Francesco; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; Negro, Michela; Ng, C. -Y.; Omodei, Nicola; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel Lawrence; Perri, Matteo; Pesce-Rollins, Melissa; Petrucci, Pierre-Olivier; Pilia, Maura; Possenti, Andrea; Puccetti, Simonetta; Rankin, John; Ratheesh, Ajay; Roberts, Oliver J.; Sgrò, Carmelo; Spandre, Gloria; Swartz, Douglas A.; Tamagawa, Toru; Tavecchio, Fabrizio; Taverna, Roberto; Tawara, Yuzuru; Thomas, Nicholas E.; Tombesi, Francesco; Trois, Alessio; Tsygankov, Sergey S.; Vink, Jacco; Wu, Kinwah; Xie, Fei; Zane, Silvia.--
Part of the Proceedings of SPIE - The International Society for Optical Engineering Volume 126782023 Article number 1267803 UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XXIII 2023 San Diego 20 August 2023 through 22 August 2023 Code 193795IXPE, the first observatory dedicated to imaging X-ray polarimetry, was launched on Dec 9, 2021 and is operating successfully. A partnership between NASA and the Italian Space Agencey (ASI) IXPE features three X-ray telescopes each comprised of a mirror module assembly with a polarization sensitive detector at its focus. An extending boom was deployed on orbit to provide the necessary 4 m focal length. A 3-axis-stabilized spacecraft provides power, attitude determination and control, and commanding. After one year of observation IXPE has measured statistically-significant polarization from almost all the classes of celestial sources that emit X-rays. In the following we describe the IXPE mission, reporting on its performance after 1.5 year of operations. We show the main astrophysical results which are outstanding for a SMEX mission. © 2023 SPIE.Peer reviewe
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