SN 1993J VLBI. II. Related Changes of the Deceleration, Flux Density Decay, and Spectrum

Bartel, N.; Bietenholz, M. F.; Rupen, M. P.; Beasley, A. J.; Graham, D. A.; Altunin, V. I.; Venturi, T.; Umana, G.; Cannon, W. H.; Conway, J.

doi:10.1086/344198

Cited by 101 publications

(160 citation statements)

References 35 publications

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“…Each group has used different data acquisition and analysis strategies. Bartel et al (2002) confirmed the deceleration reported earlier by Marcaide et al (1997), but claimed that the values of m differ for different expansion periods. Those results were in agreement with previous results from numerical simulations made by Mioduszewski et al (2001) using a rather specific explosion model.…”

Section: Introductionsupporting

confidence: 87%

“…The results from such monitoring have lent support to the SCIM initially proposed by Chevalier (1982a,b). However, Bartel et al (2002) claim to have detected departures from a self-similar expansion with regimes of changing expansion rates over different periods. In this paper, we provide evidence contrary to such claims based on our own data and on the use of new analysis tools, and support the validity of the SCIM model in which additional fine observational effects have to be taken into account.…”

Section: Introductionmentioning

confidence: 97%

“…The principal drawback of the procedure of Bartel et al (2000) was that the estimates were model-dependent. This drawback became apparent when it was found later that the emission from the central part of the source is greatly suppressed (Bartel et al 2002;Marcaide et al 2005). We refined the procedure of Marcaide et al (1997) by developing new tools that allow for accurate measurements on the sky plane, while keeping the measuring scheme model-independent.…”

Section: Introductionmentioning

confidence: 99%

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A decade of SN 1993J: discovery of radio wavelength effects in the expansion rate

Marcaide¹,

Martí-Vidal

Alberdi

et al. 2009

A&A

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We studied the growth of the shell-like radio structure of supernova SN 1993J in M 81 from September 1993 to October 2003 with very-long-baseline interferometry (VLBI) observations at the wavelengths of 3.6, 6, and 18 cm. We developed a method to accurately determine the outer radius (R) of any circularly symmetric compact radio structure such as SN 1993J. The source structure of SN 1993J remains circularly symmetric (with deviations from circularity under 2%) over almost 4000 days. We characterize the decelerated expansion of SN 1993J until approximately day 1500 after explosion with an expansion parameter m = 0.845 ± 0.005 (R ∝ t m ). However, from that day onwards the expansion differs when observed at 6 and 18 cm. Indeed, at 18 cm, the expansion can be well characterized by the same m as before day 1500, while at 6 cm the expansion appears more decelerated, and is characterized by another expansion parameter, m 6 = 0.788 ± 0.015. Therefore, since about day 1500 onwards, the radio source size has been progressively smaller at 6 cm than at 18 cm. These findings differ significantly from those of other authors in the details of the expansion. In our interpretation, the supernova expands with a single expansion parameter, m = 0.845 ± 0.005, and the 6 cm results beyond day 1500 are caused by physical effects, perhaps also coupled to instrumental limitations. Two physical effects may be involved: (a) a changing opacity of the ejecta to the 6 cm radiation; and (b) a radial decrease of the magnetic field in the emitting region. We also found that at 6 cm about 80% of the radio emission from the backside of the shell behind the ejecta is absorbed (our average estimate, since we cannot determine any possible evolution of the opacity), and the width of the radio shell is (31 ± 2)% of the outer radius. The shell width at 18 cm depends on the degree of assumed absorption. For 80% absorption, the width is (33.5 ± 1.7)%, and for 100% absorption, it is (37.8 ± 1.3)%. A comparison of our VLBI results with optical spectral line velocities shows that the deceleration is more pronounced in the radio than in the optical. This difference might be due to a progressive penetration of ejecta instabilities into the shocked circumstellar medium, as also suggested by other authors.

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Section: Introductionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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A decade of SN 1993J: discovery of radio wavelength effects in the expansion rate

Marcaide¹,

Martí-Vidal

Alberdi

et al. 2009

A&A

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“…One of the brightest RSN ever, SN1986J, has developed a complex and evolving morphology, and a spectrum which flattens over time (Bietenholz et al 2010a), however the lower limit on the expansion speed for the source in NGC 660 is significantly greater than the expansion seen in 1986J, or other nearby ordinary RSN which have been wellstudied on VLBI scales (e.g. Bartel et al 2002;Fenech et al 2010;Martí-Vidal et al 2011).…”

Section: A Single Luminous Radio Supernova/remnantmentioning

confidence: 99%

A new period of activity in the core of NGC 660

Argo

Bemmel

Connolly

et al. 2015

Mon. Not. R. Astron. Soc.

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The core of the nearby galaxy NGC 660 has recently undergone a spectacular radio outburst; using a combination of archival radio and Chandra X-ray data, together with new observations, the nature of this event is investigated. Radio observations made using e-MERLIN in mid-2013 show a new compact and extremely bright continuum source at the centre of the galaxy. High angular resolution observations carried out with the European VLBI Network show an obvious jet-like feature to the north east and evidence of a weak extension to the west, possibly a counter-jet. We also examine high angular resolution Hi spectra of these new sources, and the radio spectral energy distribution using the new wide-band capabilities of e-MERLIN. We compare the properties of the new object with possible explanations, concluding that we are seeing a period of new AGN activity in the core of this polar ring galaxy.

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“…This model uncertainty will usually dominate the uncertainty in the size estimate. Nonetheless, in most cases, angular size estimates can be made with a fractional accuracy of better than 50%, leading to estimates of the apparent expansion velocity of similar accuracy provided the distance and explosion date are well constrained (see Bartel et al 2002;Bietenholz, Soderberg, & Bartel 2009, for more detailed discussions of this process). Bietenholz & Bartel (2005 a The peak spectral luminosity of the supernova at 8.4 GHz.…”

Section: Introductionmentioning

confidence: 99%

VLBI Constraints on Type I b/c Supernovae

Bietenholz

2014

Publ. Astron. Soc. Aust.

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Very long baseline interferometry observations of supernovae and gamma-ray bursts provide almost the only way of obtaining spatially resolved information about the sources. In particular, a determination of the expansion velocity of the forward shock, as well as the geometry of the fireball and its evolution with time are possible for relatively nearby events, provided they are radio bright. Monitoring the expansion of the shock front can provide information on the density profiles of both the circumstellar material and on the ejecta. Very long baseline interferometry observations can also potentially resolve gamma-ray burst jets which are not directed along the line of sight, providing crucial confirmation of relativistic expansion in such objects. This review gives an overview of recent results from supernovae, including the Type I b/c SNe 2011dh, 2009bb, and 2007gr, and discusses the prospects for future observations.

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SN 1993J VLBI. II. Related Changes of the Deceleration, Flux Density Decay, and Spectrum

Cited by 101 publications

References 35 publications

A decade of SN 1993J: discovery of radio wavelength effects in the expansion rate

A decade of SN 1993J: discovery of radio wavelength effects in the expansion rate

A new period of activity in the core of NGC 660

VLBI Constraints on Type I b/c Supernovae

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