The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant

Fesen, Robert A.; Hammell, Molly; Morse, Jon A.; Chevalier, Roger A.; Borkowski, Kazimierz J.; Dopita, Michael A.; Gerardy, Christopher L.; Lawrence, Stephen S.; Raymond, J. C.; Bergh, Sidney van den

doi:10.1086/504254

Cited by 302 publications

(347 citation statements)

References 101 publications

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“…If the measurements of presolar grains by Nittler et al (1996), Clayton et al (1997), andHoppe et al (2000) are taken into account, which suggest that the ratio 44 Ca/ 40 Ca can be more than 100 times higher than solar, the forward-shock 44 Ca density is scaled down correspondingly to 10 3 -10 4 cm −3 . Although this density range appears plausible for optical knots and might even be consistent with expectations (Fesen et al 2006;Docenko & Sunyaev 2010), the estimated values appear extreme: Assuming a volume of the swept-up material near the Cas A SNR of ∼10 56 cm 3 , and a density of ∼10 3 cm −3 , the estimated 44 Ca mass would be of the order 10 3 M . Therefore, the ejecta from Cas A alone cannot explain this mass; adding the swept-up interstellar material cannot explain the additional flux either.…”

Section: Nuclear De-excitation?supporting

confidence: 52%

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Siegert

Diehl

Krause

et al. 2015

A&A

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Context. The 340-yr old supernova remnant Cassiopeia A, located at 3.4 kpc distance, is the best-studied young core-collapse supernova remnant. Nucleosynthesis yields in radioactive isotopes have been studied with different methods, in particular for production and ejection of 44 Ti and 56 Ni, which originate in the innermost regions of the supernova. 44 Ti was first discovered in this remnant, but is not seen consistently in other core-collapse sources. Aims. We aim to measure radioactive 44 Ti ejected in Cassiopeia A and to place constraints on velocities of these ejecta by determining X-and γ-ray line-shape parameters of the emission lines. Methods. We analyzed the observations made with the SPI spectrometer on INTEGRAL together with an improved instrumental background method, to achieve a high spectroscopic resolution that enables interpretation for a velocity constraint on 44 Ti ejecta from the 1.157 MeV γ-ray line of the 44 Sc decay. Results. We observe both the hard X-ray line at 78 keV and the γ-ray line at 1157 keV from the 44 Ti decay chain at a combined significance of 3.8σ. Measured fluxes are (2.1 ± 0.4) × 10 −5 ph cm −2 s −1 and (3.5 ± 1.2) × 10 −5 ph cm −2 s −1 , which corresponds to (1.5 ± 0.4) × 10 −4 and (2.4 ± 0.9) × 10 −4 M of 44 Ti, respectively. The measured Doppler broadening of the lines implies expansion velocities of 4300 and 2200 km s −1 , respectively. By combining our results with previous studies, we determine a more precise estimate of ejected 44 Ti of (1.37 ± 0.19) × 10 −4 M . Conclusions. The measurements of the two lines are consistent with previous studies. The flux in the line originating from excited 44 Ca is significantly higher than the flux determined in the lines from 44 Sc. Cosmic-ray acceleration within the supernova remnant may be responsible for an additional contribution to this line from nuclear de-excitation following energetic particle collisions in the remnant and swept-up material.

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Section: Nuclear De-excitation?supporting

confidence: 52%

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Siegert

Diehl

Krause

et al. 2015

A&A

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“…This result that asphericites are an ubiquitous feature during core-collapse is in line with similar conclusions based on polarization studies of SN II, Ib and SN Ic e.g., (Leonard & Filippenko 2005;Maund et al 2009a), neutron-star kick velocities (Wang et al 2006), young SN remnant morphologies (Fesen et al 2006), and theoretical modeling efforts (Scheck et al 2006;Burrows et al 2006;Dessart et al 2008). Aspherical explosion geometry does not appear to be distinguishing feature of SN-GRBs, though SN-GRBs may have the highest degree of asphericity according to some models (Maeda et al 2008).…”

Section: Relative Rates Of Sn Ic-bl Vs Lgrbsupporting

confidence: 92%

Stellar Forensics with the Supernova‐GRB Connection

Modjaz¹

2011

Reviews in Modern Astronomy

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Long-duration gamma-ray bursts (GRBs) and Type Ib/c Supernovae (SNe Ib/c) are amongst nature's most magnificent explosions. While GRBs launch relativistic jets, SNe Ib/c are core-collapse explosions whose progenitors have been stripped of their hydrogen and helium envelopes. Yet for over a decade, one of the key outstanding questions is which conditions lead to each kind of explosion and death in massive stars. Determining the fates of massive stars is not only a vibrant topic in itself, but also impacts using GRBs as star formation indicators over distances of up to 13 billion light-years and for mapping the chemical enrichment history of the universe. This article reviews a number of comprehensive observational studies that probe the progenitor environments, their metallicities and the explosion geometries of SN with and without GRBs, as well as the emerging field of SN environmental studies. Furthermore, it discusses SN 2008D/XRT 080109 which was discovered serendipitously with the Swift satellite via its X-ray emission from shock breakout, and which has generated great interest amongst both observers and theorists while illustrating a novel technique for stellar forensics. The article concludes with an outlook on how the most promising venues of research -with the many existing and upcoming large-scale surveys such as the Palomar Transient Factory and LSST -will shed new light on the diverse deaths of massive stars.

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“…The regions observed by ISO are shown in Fig. 4 Fesen et al 2006). 6 Here and everywhere below the "line ratio" denotes the ratio of the line fluxes in energy units.…”

Section: Iso Observationsmentioning

confidence: 99%

“…7 Results in this section are based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) and with the participation of ISAS and NASA. 8 http://www.iso.vilspa.esa.es/ida/ (Fesen et al 2006). North is upwards and East is to the left.…”

Section: Iso Observationsmentioning

confidence: 99%

Fine-structure infrared lines from the Cassiopeia A knots

Docenko

Sunyaev

2010

A&A

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Aims. Archival observations of infrared fine-structure lines of the young Galactic supernova remnant Cassiopeia A allow us to test existing models and determine the physical parameters of various regions of the fast-moving knots, which are metal-dominated clouds of material ejected by the supernova explosion. Spitzer data are used to determine the fluxes of the O, Ne, Si, S, Ar, and Fe ion fine-structure lines originating in the fast-moving knots. The ratios of these line fluxes are used as plasma diagnostics. We also determine the infrared line flux ratios with respect to the optical [O iii] 5007 Å line in the knots with previously measured reddening. Additionally, we analyze several optical and near-infrared observations of the fast-moving knots to obtain clearer insight into the post-shock photoionized region structure. Results. We show that the infrared oxygen line flux predictions of all existing theoretical models are correct only to within a factor of a several. Comparison of the model predictions shows that to reproduce the observations it is essential to include the effects of the electron conductivity and dust. Detailed analysis of the diagnostic line flux ratios of various ions allows us to qualitatively confirm the general model of fast-moving knot emission and determine observationally for the first time the physical conditions in the photoionized region after the shock. We infer from the [O iii] line flux ratios that the pre-shock cloud densities are higher than assumed in existing theoretical models and most probably correspond to several hundred particles per cm 3 . We also determine the Cas A luminosity in the infrared continuum and lines. We show that accounting for the charge exchange processes in the post-shock photoionized region allows us to reproduce most of the relevant spectral line ratios even in the frame of a single-temperature model of this region. We also estimate its plasma parameters, thickness, and carbon abundance.

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The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant

Cited by 302 publications

References 101 publications

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Stellar Forensics with the Supernova‐GRB Connection

Fine-structure infrared lines from the Cassiopeia A knots

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The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant

Cited by 302 publications

References 101 publications

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

Stellar Forensics with the Supernova‐GRB Connection

Fine-structure infrared lines from the Cassiopeia A knots

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Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A