Multifrequency Radio Measurements of Supernova 1987a Over 22 Years

Zanardo, Giovanna; Staveley‐Smith, L.; Ball, Lewis; Gaensler, B. M.; Kesteven, Michael; Manchester, R. N.; Ng, C.‐Y.; Tzioumis, A. K.; Potter, Toby

doi:10.1088/0004-637x/710/2/1515

Cited by 68 publications

(130 citation statements)

References 52 publications

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“…The present work concentrates on the nonthermal characteristics and, in particular, on the particle acceleration aspects and the expected γ -ray emission. It extends two earlier studies by Berezhko & Ksenofontov (2000), and by Berezhko & Ksenofontov (2006, hereafter referred to as BK), to include the subsequent Chandra observations of the soft and hard X-ray emission (Park et al 2007), as well as the most recent and very detailed observations of the radio continuum emission by Zanardo et al (2010). At the same time a qualitative and in fact semi-quantitative prediction of the future nonthermal emission from this source for the next decades is attempted.…”

Section: Introductionsupporting

confidence: 58%

“…The present paper assumes such a simplification to be the main reason why a corresponding theoretical model fits the data only on average. This concerns the shape of the radio spectrum and the time dependence of the radio flux over an extended period of SNR evolution (Zanardo et al 2010). In the case of SN 1987A, on the other hand, it is natural to expect substantial time variations of these injection parameters since the SN shock propagates through a strongly nonuniform CSM whose physical parameters at the shock front are expected to change in time.…”

Section: Particle Acceleration Modelmentioning

confidence: 99%

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Expected Gamma-Ray Emission of Supernova Remnant Sn 1987a

Berezhko

Ksenofontov

Völk

2011

ApJ

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A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is employed to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5-100 yr. It is shown that an efficient production of nuclear CRs leads to a strong modification of the outer SNR shock and to a large downstream magnetic field B d ≈ 20 mG. The shock modification and the strong field are required to yield the steep radio emission spectrum observed, as well as the considerable synchrotron cooling of high-energy electrons which diminishes their X-ray synchrotron flux. These features are also consistent with the existing X-ray observations. The expected γ -ray energy flux at TeV energies at the current epoch is nearly γ F γ ≈ 4 × 10 −13 erg cm 2 s −1 under reasonable assumptions about the overall magnetic field topology and the turbulent perturbations of this field. The general nonthermal strength of the source is expected to increase roughly by a factor of two over the next 15-20 years; thereafter, it should decrease with time in a secular form.

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Section: Introductionsupporting

confidence: 58%

Section: Particle Acceleration Modelmentioning

confidence: 99%

Expected Gamma-Ray Emission of Supernova Remnant Sn 1987a

Berezhko

Ksenofontov

Völk

2011

ApJ

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“…The outer ejecta of SN 1987A travelling at around 30 000 km s −1 have reached the outer ring a decade ago, and have become visible mostly in the reverse shocks generated by the collision with the ring material (McCray 2003;Gröningsson et al 2006Gröningsson et al , 2008bKjaer et al 2007;Zanardo et al 2010). The inner ejecta are still heated by the radioactive decays (mostly positrons from the 44 Ti decays; Fransson & Kozma 2002) and have expanded enough to be spatially resolved.…”

Section: Discussionmentioning

confidence: 99%

The 3-D structure of SN 1987A's inner ejecta

Kjaer¹,

Leibundgut

Fransson

et al. 2010

A&A

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Context. Observing the inner ejecta of a supernova is possible only in a handful of nearby supernova remnants. The core-collapse explosion mechanism has been extensively explored in recent models and predict large asymmetries. SN 1987A is the first modern stellar explosion that has been continuously observed from its beginning to the supernova remnant phase. Twenty years after the explosion, we are now able to observe the three-dimensional spatially resolved inner ejecta of this supernova. Aims. Detailed mapping of newly synthesised material and its radioactive decay daughter products sheds light on the explosion mechanism. This may reveal the geometry of the explosion and its connection to the equatorial ring and the outer rings around SN 1987A. Methods. We have used integral field spectroscopy to image the supernova ejecta and the equatorial ring in the emission lines of [Si I] + [Fe II] (λ1.64 μm) and He I (λ2.058 μm). The spectral information can be mapped into a radial velocity image revealing the expansion of the ejecta both as projected onto the sky and perpendicular to the sky plane. Results. The inner ejecta are spatially resolved in a North-South direction and are clearly asymmetric. Like the ring emission, the northern parts of the ejecta are blueshifted, while the material projected to the South of the supernova centre is moving away from us. We argue that the bulk of the ejecta is situated in the same plane as defined by the equatorial ring and does not form a bipolar structure as has been suggested. The exact shape of the ejecta is modelled and we find that an elongated triaxial ellipsoid fits the observations best. The velocity measured in the [Si I] + [Fe II] line corresponds to ∼3000 km s −1 and is the same as the width of the IR [Fe II] line profiles during the first years. From our spectral analyses of the ejecta spectrum we find that most of the He I, [Si I] and [Fe I-II] emission originates in the core material which has undergone explosive nucleosynthesis. The He I emission may be the result of α-rich freeze-out if the positron energy is deposited locally. Conclusions. Our observations clearly indicate a non-symmetric explosion mechanism for SN 1987A. The elongation and velocity asymmetries point towards a large-scale spatial non-spherical distribution as predicted in recent explosion models. The orientation of the ejecta in the plane of the equatorial ring argues against a jet-induced explosion through the poles due to stellar rotation.

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“…3, where the IR data comprise groundbased nearand mid-IR, and Spitzer observations published by Bouchet et al (2006), AKARI observations published by Seok et al (2008), a Spitzer 70-μm upper limit published by Dwek et al (2010) and Herschel observations published by Matsuura et al (2011) 1 . The radio data solely comprise ATCA observations, published by Manchester et al (2005), Potter et al (2009), and by the most up-to-date summary at the longest wavelengths by Zanardo et al (2010). In Fig.…”

Section: Bridging the Ir And Radio Spectral Energy Distributionsmentioning

confidence: 99%

“…Its circumburst environment has been studied in great detail, revealing a dusty equatorial ring ∼2 in diameter (Bouchet et al 2006) with two fainter isomorphological rings -but offset from the former -on either side of SN 1987A. The light echo from SN 1987A has been used to probe the surrounding ISM (Xu et al 1995 regions around day 6000 and the resulting increased radiation is observed at all frequencies (Dwek et al 2010;Zanardo et al 2010).…”

Section: Introductionmentioning

confidence: 99%

The remnant of SN 1987A revealed at (sub-)mm wavelengths

Lakićević

Loon

Patat

et al. 2011

A&A

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Context. Supernova 1987A (SN 1987A) exploded in the Large Magellanic Cloud (LMC). Its proximity and rapid evolution makes it a unique case study of the early phases in the development of a supernova remnant. One particular aspect of interest is the possible formation of dust in SN 1987A, as SNe could contribute significantly to the dust seen at high redshifts. Aims. We explore the properties of SN 1987A and its circumburst medium as seen at mm and sub-mm wavelengths, bridging the gap between extant radio and infrared (IR) observations of respectively the synchrotron and dust emission. Results. SN 1987A is detected as an unresolved point source of 11.2 ± 2.0 mJy at 3.2 mm (5 beam) and 21 ± 4 mJy at 0.87 mm (18 beam). These flux densities are in perfect agreement with extrapolations of the powerlaw radio spectrum and modified-blackbody dust emission, respectively. This places limits on the presence of free-free emission, which is similar to the expected free-free emission from the ionized ejecta from SN 1987A. Adjacent, fainter emission is observed at 0.87 mm extending ∼0.5 towards the south-west. This could be the impact of the supernova progenitor's wind when it was still a red supergiant upon a dense medium. Conclusions. We have established a continuous spectral energy distribution for the emission from SN 1987A and its immediate surroundings, linking the IR and radio data. This places limits on the contribution from ionized plasma. Our sub-mm image reveals complexity in the distribution of cold dust surrounding SN 1987A, but leaves room for freshly synthesized dust in the SN ejecta.

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Multifrequency Radio Measurements of Supernova 1987a Over 22 Years

Cited by 68 publications

References 52 publications

Expected Gamma-Ray Emission of Supernova Remnant Sn 1987a

Expected Gamma-Ray Emission of Supernova Remnant Sn 1987a

The 3-D structure of SN 1987A's inner ejecta

The remnant of SN 1987A revealed at (sub-)mm wavelengths

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