<i>Spitzer</i>IRAC Images and Sample Spectra of Cassiopeia A’s Explosion

Ennis, J.; Rudnick, Lawrence; Reach, W. T.; Smith, John David; Rho, Jeonghee; DeLaney, Tracey; Gomez, Haley Louise; Kozasa, Takashi

doi:10.1086/508142

Cited by 66 publications

(107 citation statements)

References 49 publications

(87 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lines of Ar, Si, and S are very faint in these regions, and they have excess 4.5 μm brightness (Ennis et al 2006). The blended complex [O iv]+[Fe ii] is strong as well, though the coarser angular resolution prevents completely separating the small regions from the surrounding ring material at these longer wavelengths.…”

Section: Apparent Inhomogenous Mixing and The Neon Crescentsmentioning

confidence: 99%

“…A model of the composition and mass of emitting dust associated with the remnant using this MIR data set was undertaken by Rho et al (2008). Ennis et al (2006) highlighted the associated deep 3.6-8 μm Spitzer IRAC imaging, exploring the survival of the various nuclear burning layers. Here, we present the distribution of the global fine structure infrared emission lines and constrain conditions in the emitting environments over the full remnant.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

SPITZERSPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A

Smith¹,

Rudnick²,

DeLaney³

et al. 2009

ApJ

Self Cite

114

View full text Add to dashboard Cite

We present the global distribution of fine-structure infrared line emission in the Cassiopeia A supernova remnant using data from the Spitzer Space Telescope's infrared spectrograph. We identify emission from ejecta materials in the interior, prior to their encounter with the reverse shock, as well as from the postshock bright ring. The global electron density increases by 100 at the shock to ∼ 10 4 cm −3 , providing evidence for strong radiative cooling. There is also a dramatic change in ionization state at the shock, with the fading of emission from low-ionization interior species like [Si ii] giving way to [S iv] and, at even further distances, highenergy X-rays from hydrogenic silicon. Two compact, crescent-shaped clumps with highly enhanced neon abundance are arranged symmetrically around the central neutron star. These neon crescents are very closely aligned with the "kick" direction of the compact object from the remnant's expansion center, tracing a new axis of explosion asymmetry. They indicate that much of the apparent macroscopic elemental mixing may arise from different compositional layers of ejecta now passing through the reverse shock along different directions.

show abstract

Section: Apparent Inhomogenous Mixing and The Neon Crescentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

SPITZERSPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A

Smith¹,

Rudnick²,

DeLaney³

et al. 2009

ApJ

Self Cite

114

View full text Add to dashboard Cite

show abstract

“…Limits to the [Ne v] line ratio also do not provide strong constraints partly because of spectral fringing near 20 μm in the IRS spectra (Ennis et al 2006 Existence of Ar 4+ in the pre-shock region (see Table 6) is understandable, given its relatively low Ar 3+ ionization potential of 60 eV, comparable to the ionization potential of O 2+ (55 eV). Therefore, similar amounts of O 2+ and O 3+ in the pre-shock photoionized region in the SD-200 model give us a reason to deduce that Ar 3+ and Ar 4+ ions also have similar number densities.…”

Section: [O I] Fir Line Flux Ratiomentioning

confidence: 99%

Fine-structure infrared lines from the Cassiopeia A knots

Docenko

Sunyaev

2010

A&A

View full text Add to dashboard Cite

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.

show abstract

“…Additional low-resolution spectra were collected for outlying regions in the vicinity of the SNR. Two of the closest regions to the SNR, located within the northeast jet of ejecta and the southwest counterjet, have emission lines and the 22 m silicate feature that are characteristic of ejecta material (Ennis et al 2006;Rho et al 2008). Spectra of other regions exhibited a flat continuum and coincide with highly variable features, and are therefore assumed to be representative echo spectra.…”

Section: The Discovery Of the Echoesmentioning

confidence: 99%

Infrared Echoes Reveal the Shock Breakout of the Cas A Supernova

Dwek¹,

Arendt²

2008

Astrophysical Journal

View full text Add to dashboard Cite

Through the serendipitous discovery of infrared echoes around the Cas A supernova remnant, the Spitzer satellite has provided astronomers with a unique opportunity to study the properties of the echoing material and the history and nature of the outburst that generated these echoes. In retrospect, we find that the echoes are also clearly visible as infrared ''hot spots'' in IRAS images of the region. The spectra of the echoes are distinct from that of the dust in the general diffuse interstellar medium (ISM ), revealing hot silicate grains that are either stochastically heated to temperatures in excess of $150 K or radiating at an equilibrium temperature of this value. We show that the maximum luminosity that can be generated by the radioactive decay of 56 Ni is not capable of producing such spectra, and could therefore not have given rise to the echoes. Instead, we find that the echoes must have been generated by an intense and short burst of EUV-UV radiation associated with the breakout of the shock through the surface of the exploding star. The inferred luminosity of the burst depends on the amount of attenuation in the intervening medium to the clouds, and we derive a burst luminosity of $1:5 ; 10 11 L for an assumed H-column density of 1:5 ; 10 19 cm À2 . The average H-column density of the IR-emitting region in the echoing clouds is about 5 ; 10 17 cm À2 . Derivation of their density requires knowledge of the width of the echo that is sweeping through the ISM, which in turn is determined by the duration of the burst. A burst time of $1 day gives a cloud density of $400 cm À3 , typical of dense IR cirrus.

show abstract

SpitzerIRAC Images and Sample Spectra of Cassiopeia A’s Explosion

Cited by 66 publications

References 49 publications

SPITZERSPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A

SPITZERSPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A

Fine-structure infrared lines from the Cassiopeia A knots

Infrared Echoes Reveal the Shock Breakout of the Cas A Supernova

Contact Info

Product

Resources

About