Constraints on the kinematics of the ${^{44}}$Ti ejecta of Cassiopeia A from INTEGRAL/SPI

Martin, Pierrick; Knödlseder, J.; Vink, Jacco; Decourchelle, A.; Renaud, M.

doi:10.1051/0004-6361/200809735

Cited by 30 publications

(51 citation statements)

References 35 publications

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“…The distribution of these sky residuals should then follow a statistical distribution, the shape of which is derived from simulated observations. This method is described in greater detail in Martin et al (2009) and proved that our hypotheses regarding both the background noise and the sky intensity distribution are satisfactory and that the results obtained are not affected by systematic errors.…”

Section: Model Fittingmentioning

confidence: 77%

New estimates of the gamma-ray line emission of the Cygnus region from INTEGRAL/SPI observations

Martin

Knödlseder

Diehl

et al. 2009

A&A

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Context. The Cygnus region harbours a huge complex of massive stars at a distance of 1.0-2.0 kpc from us. About 170 O stars are distributed over several OB associations, among which the Cyg OB2 cluster is by far the largest with about 100-120 O stars. As a consequence of their successive nuclear-burning episodes, these massive stars inject large quantities of radioactive nuclei into the interstellar medium such as 26 Al and 60 Fe. The gamma-ray line signal from the latter is a solid tracer of ongoing nucleosynthesis. Aims. We want to compare the decay emission from the Cygnus region with predictions of recently improved stellar models. As a first step, we establish observational constraints upon the gamma-ray line emission from 26 Al and 60 Fe, with particular emphasis placed on separating the emission due to the Cygnus complex from the foreground and background mean Galactic contributions. Methods. We used the high-resolution gamma-ray spectrometer INTEGRAL/SPI to analyse the 26 Al and 60 Fe decay signal from the Cygnus region. The weak gamma-ray line emissions at 1809 and 1173/1332 keV have been characterised in terms of photometry, spectrometry, and source morphology. Results. The 1809 keV emission from Cygnus is centred on the position of the Cyg OB2 cluster and has a typical size of 9 • or more. The total 1809 keV flux from the Cygnus region is (6.0 ± 1.0) × 10 −5 ph cm −2 s −1 , but the flux really attributable to the Cygnus complex reduces to (3.9 ± 1.1) × 10 −5 ph cm −2 s −1 . The 1809 keV line centroid agrees with expectations considering the direction and distance of the Cygnus complex, and the line width is consistent with typical motions of the interstellar medium. No decay emission from 60 Fe has been observed from the Cygnus region and an upper limit of 1.6 × 10 −5 ph cm −2 s −1 was derived. Conclusions. The determination in a coherent way of the gamma-ray line emission of the clustered OB population of the nearby Cygnus complex will allow a more accurate comparison of observations with theoretical expectations based on the most recent stellar models.

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Section: Model Fittingmentioning

confidence: 77%

New estimates of the gamma-ray line emission of the Cygnus region from INTEGRAL/SPI observations

Martin

Knödlseder

Diehl

et al. 2009

A&A

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“…Both INTEGRAL main telescopes are sensitive to 44 Ti gamma-rays: The IBIS telescope obtained a flux value of (2.3±0.5) 10 −5 ph cm −2 s −1 [107] from the 68 and 78 keV lines. From the SPI spectrometer, an initial report of a detection consistent with expectations [87] was corrected later towards an upper flux limit, owed to large variations of background during observations [88]. This has been translated into an amount of 44 Ti at the time of explosion of 1.6 x 10 −4 M , with an uncertainty of ( +0.6 / −0.3 ) M .…”

Section: The Iron and Velocity Distribution In Cassiopeia Amentioning

confidence: 88%

“…Maeda & Nomoto (2003) show bipolar supernova explosion caused by a pair of opposit dynamic jets fed by accretion brings the material on the to higher temperatures than that reached in spherical and hence causes a more rapid expansion and hence a alpha-rich freeze-out for that material. This results p in an augmented 44 Ti yield, but the hydrodynamics as with that scenario also leads to an inversion of the v along the jet where 44 Ti and 56 Ni have the highest v If we assume that the data do not show any line at the expected energy of 1157 keV, the Cas A line must be broadened by at least 500 km s −1 for statistical consistency (2σ) [88]. detailed supernova model.…”

Section: The Iron and Velocity Distribution In Cassiopeia Amentioning

confidence: 95%

“…Thus the 44 Ti ejection from the Cas A supernova was a factor of three above predictions from models. The non-detection of the 1157 keV decay line by INTEGRAL's SPI instrument [88] (Fig. 9) suggests that 44 Ti-rich ejecta move at velocities above 500 km s −1 [88].…”

Section: The Iron and Velocity Distribution In Cassiopeia Amentioning

confidence: 99%

“…The non-detection of the 1157 keV decay line by INTEGRAL's SPI instrument [88] (Fig. 9) suggests that 44 Ti-rich ejecta move at velocities above 500 km s −1 [88]. As Doppler broadening increases with photon energy, this makes the high-energy decay line much broader than SPI's instrumental resolution, hence the signal-to-background ratio for this line degrades and may escape detection, less so the 68 and 78 keV lines which have been measured consistently from Cas A.…”

Section: The Iron and Velocity Distribution In Cassiopeia Amentioning

confidence: 99%

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Cosmic Gamma-Ray Spectroscopy

Diehl

2013

Astronomical Review

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Penetrating gamma-rays require complex instrumentation for astronomical spectroscopy measurements of gamma-rays from cosmic sources. Multiple-interaction detectors in space combined with sophisticated postprocessing of detector events on ground have lead to a spectroscopy performance which is now capable to provide new astrophysical insights. Spectral signatures in the MeV regime originate from transitions in the nuclei of atoms (rather than in their electron shell). Nuclear transitions are stimulated by either radioactive decays or high-energy nuclear collisions such as with cosmic rays. Gamma-ray lines have been detected from radioactive isotopes produced in nuclear burning inside stars and supernovae, and from energetic-particle interactions in solar flares. Radioactive-decay gamma-rays from 56 Ni directly reflect the source of supernova light. 44 Ti is produced in core-collapse supernova interiors, and the paucity of corresponding 44 Ti gamma-ray line sources reflects the variety of dynamical conditions herein. 26 Al and 60 Fe are dispersed in interstellar space from massive-star nucleosynthesis over millions of years. Gamma-rays from their decay are measured in detail by gamma-ray telescopes, astrophysical interpretations reach from massive-star interiors to dynamical processes in the interstellar medium. Nuclear de-excitation gamma-ray lines have been found in solar-flare events, and convey information about energetic-particle production in these events, and their interaction in the solar atmosphere. The annihilation of positrons leads to another type of cosmic gamma-ray source. The characteristic annihilation gamma-rays at 511 keV have been measured long ago in solar flares, and now throughout the interstellar medium of our Milky Way galaxy. But now a puzzle has appeared, as a surprising predominance of the central bulge region was determined. This requires either new positron sources or transport processes not yet known to us. In this paper we discuss instrumentation and data processing for cosmic gamma-ray spectroscopy, and the astrophysical issues and insights from these measurements.

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Massive Stars and Their Supernovae

Thielemann¹,

Diehl²,

Heger³

et al. 2018

Astrophysics With Radioactive Isotopes

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Our understanding of stellar evolution and the final explosive endpoints such as supernovae or hypernovae or gamma-ray bursts relies on the combination of a) (magneto-)hydrodynamics b) engergy generation due to nuclear reactions accomanying composition changes c) radiation transport d) thermodynamic properties (such as the equation of state of stellar matter).Hydrodynamics is essentially embedded within the numerical schemes which implement the physics of processes (b) to (d). In early phases of stellar evolution, hydrodynamical processes can be approximated by a hydrostatic treatment. Nuclear energy production (b) includes all nuclear reactions triggered during stellar evolution and explosive end stages, also among unstable isotopes produced on the way. Radiation transport (c) covers atomic physics (e.g. opacities) for photon transport, but also nuclear physics and neutrino nucleon/nucleus interactions in late phases and core collapse. The thermodynamical treatment (d) addresses the mixture of ideal gases of photons, electrons/positrons and nuclei/ions. These are fermions and bosons, in dilute media or at high temperatures their energies can often be approximated by Maxwell-Boltzmann distributions. At very high densities, the nuclear equation of state is required to relate pressure and density. It exhibits a complex behavior, with transitions from individual nuclei to clusters of nucleons with a background neutron bath, homogeneous phases of nucleons, the emergence of hyperons and pions up to a possible hadron-quark phase transition.The detailed treatment of all these ingredients and their combined application is discussed in more depth in textbooks (Kippenhahn and Weigert, 1994; Maeder, /or the preceding Chapter (3), where the evolution of low and intermediate mass stars is addressed. That chapter also includes the stellar structure equations in spherical symmetry and a discussion of opacities for photon transport. Ch. 8 and 9 (tools for modeling objects and their processes) go into more detail with regard to modeling hydrodynamics, (convective) instabilities and energy transport as well as the energy generation due to nuclear reactions and the determination of the latter. Here we want to focus on the astrophysical aspects, i.e. a description of the evolution of massive stars and their endpoints with a special emphasis on the composition of their ejecta (in form of stellar winds during the evolution or of explosive ejecta). Low and intermediate mass stars end their evolution as AGB stars, finally blowing off a planetary nebula via wind losses and leaving a white dwarf with an unburned C and O composition. Massive stars evolve beyond this point and experience all stellar burning stages from H over He, C, Ne, O and Si-burning up to core collapse and explosive endstages. In this chapter we want to discuss the nucleosynthesis processes involved and the production of radioactive nuclei 5 in more detail. This includes all hydrostatic nuclear-burning stages experienced by massive stars, and explosive burning stages wh...

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Constraints on the kinematics of the ${^{44}}$Ti ejecta of Cassiopeia A from INTEGRAL/SPI

Cited by 30 publications

References 35 publications

New estimates of the gamma-ray line emission of the Cygnus region from INTEGRAL/SPI observations

New estimates of the gamma-ray line emission of the Cygnus region from INTEGRAL/SPI observations

Cosmic Gamma-Ray Spectroscopy

Massive Stars and Their Supernovae

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