- ID:
- ivo://CDS.VizieR/J/A+A/581/A126
- Title:
- Application of the D^3^PO algorithm
- Short Name:
- J/A+A/581/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the 6.5yr all-sky data from the Fermi LAT restricted to gamma-ray photons with energies between 0.6-307.2GeV. We present a non-parametric reconstruction of the diffuse photon flux up to several hundred GeV, its all-sky spectral index map, and its angular power spectrum. We decompose the diffuse emission into a cloud-like abd a bubble-like component and analyze their spectra. Additionally, we wrote up a catalog of source candidates that includes 3106 sources. For each source we report the location in the sky, flux, spectral index, and possible associations with sources from the second and third Fermi source catalog.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/747/L19
- Title:
- A search for SNR 0519-69.0 progenitors
- Short Name:
- J/ApJ/747/L19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for an ex-companion star in SNR 0519-69.0, located in the Large Magellanic Cloud, based on images taken with the Hubble Space Telescope with a limiting magnitude of V=26.05. SNR 0519-69.0 is confidently known to be from a Type Ia supernova based on its light echoes and X-ray spectra. The geometric center of the remnant (based on the H{alpha} and X-ray shell) is at 05:19:34.83, -69:02:06.92 (J2000). Accounting for the measurement uncertainties, the orbital velocity, and the kick velocity, any ex-companion star must be within 4.7" of this position at the 99.73% confidence level. This circle contains 27 main-sequence stars brighter than V=22.7, any one of which could be the ex-companion star left over from a supersoft source progenitor system. The circle contains no post-main-sequence stars, and this rules out the possibility of all other published single-degenerate progenitor classes (including symbiotic stars, recurrent novae, helium donors, and the spin-up/spin-down models) for this particular supernova. The only remaining possibility is that SNR 0519-69.0 was formed from either a supersoft source or a double-degenerate progenitor system.
- ID:
- ivo://CDS.VizieR/J/A+A/481/169
- Title:
- ATCA 3mm obs. of NGC 6334I and NGC 6334I(N)
- Short Name:
- J/A+A/481/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the dense gas, the outflows, and the continuum emission from the massive twin cores NGC 6334I and I(N) at high spatial resolution. We imaged the region with the Australia Telescope Compact Array (ATCA) at 3.4mm wavelength in continuum, as well as CH_3_CN (5_K_-4_K_) and HCN(1-0) spectral line emission.
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/44
- Title:
- ATCA SMC Radio Continuum Source. II.
- Short Name:
- J/MNRAS/355/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the classification of 717 radio-continuum sources from the Australia Telescope Compact Array (ATCA) Catalogue of the Small Magellanic Cloud (SMC). All 717 sources have been categorised into one of three groups: supernova remnants (SNRs), HII regions and background sources. In total, we name 71 sources as HII regions (or candidates) and 21 sources as SNRs (or candidates). Six sources are named as either HII regions or background sources and two are candidate radio planetary nebulae. One source is coincident with an X-ray binary. We classify 616 objects as background sources and present their statistics.
- ID:
- ivo://CDS.VizieR/J/AJ/104/704
- Title:
- A VLA Search for Young Galactic Supernova Remnants
- Short Name:
- J/AJ/104/704
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the attempt to identify very young galactic supernova remnants (SNRs), 290 known compact (<2') galactic plane radio sources were observed at 20cm using the VLA in its 36 km configuration. The VLA observations described could detect supernovae with diameters between 5 and 20"; these would have an age of between 25 and 100 yr. Compact structure was detected in 168 (58%) of the 290 different sources observed; 73 sources (25%) were unresolved or slightly resolved point sources, 21 (7%) were single-well resolved, 56 (19%) were double, 18 (6%) were triple or complex. The large scale structure was completely resolved out for 122 (42%) of sources. Additional observations at 6cm with the VLA in the 11 km configuration were made of 14 sources with apparent shell structures that might have been characteristic of young SNRs. Low resolution observations were made at 20cm of 62 fields where the source was completely resolved out in the high resolution images. Only one source, G25.5+0.2, is a possible very young SNR. New H66_alpha recombination line observations place severe constrains on any thermal interpretation for this object.
- ID:
- ivo://CDS.VizieR/J/A+A/435/437
- Title:
- Brightness and diameters for extragalactic SNRs
- Short Name:
- J/A+A/435/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper examines relations between the radio surface brightness Sigma and the diameter D (also known as Sigma-D relations) for a sample of extragalactic supernova remnants (SNRs) as constructed from a combination of published data and data from our own surveys. Our sample of extragalactic SNRs is the largest ever devised for the purpose of analyzing Sigma-D relations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/2026
- Title:
- Calibration of some distance scales
- Short Name:
- J/MNRAS/440/2026
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method for distance calibration without using standard fitting procedures. Instead, we use random resampling to reconstruct the probability density function (PDF) of calibration data points in the fitting plane. The resulting PDF is then used to estimate distance-related properties. The method is applied to samples of radio surface brightness to diameter ({Sigma}-D}) data for the Galactic supernova remnants (SNRs) and planetary nebulae (PNe), and period-luminosity (PL) data for the Large Magellanic Cloud (LMC) fundamental mode classical Cepheids. We argue that resulting density maps can provide more accurate and more reliable calibrations than those obtained by standard linear fitting procedures. For the selected sample of the Galactic SNRs, the presented PDF method of distance calibration results in a smaller average distance fractional error of up to ~16 percentage points. Similarly, the fractional error is smaller for up to ~8 and ~0.5 percentage points, for the samples of Galactic PNe and LMC Cepheids, respectively. In addition, we provide a PDF-based calibration data for each of the samples.
- ID:
- ivo://CDS.VizieR/J/ApJ/613/343
- Title:
- Cas A knot and filament proper motions
- Short Name:
- J/ApJ/613/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution X-ray proper-motion measurements of Cassiopeia A using Chandra X-Ray Observatory observations from 2000 and 2002. We separate the emission into four spectrally distinct classes: Si-dominated, Fe-dominated, low-energy-enhanced, and continuum-dominated. These classes also represent distinct spatial and kinematic components.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A110
- Title:
- Cas A LOFAR and VLA images
- Short Name:
- J/A+A/612/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cassiopeia A is one of the best-studied supernova remnants. Its bright radio and X-ray emission is due to shocked ejecta. Cas A is rather unique in that the unshocked ejecta can also be studied: through emission in the infrared, the radio-active decay of ^44^Ti, and the low-frequency free-free absorption caused by cold ionised gas, which is the topic of this paper. Free-free absorption processes are acted by the mass, geometry, temperature, and ionisation conditions in the absorbing gas. Observations at the lowest radio frequencies can constrain a combination of these properties. We used Low Frequency Array (LOFAR) Low Band Antenna observations at 30-77MHz and Very Large Array (VLA) L-band observations at 1-2GHz to fit for internal absorption as parametrised by the emission measure. We simultaneously fit multiple UV-matched images with a common resolution of 17" (this corresponds to 0.25pc for a source at the distance of Cas A). The ample frequency coverage allows us separate the relative contributions from the absorbing gas, the unabsorbed front of the shell, and the absorbed back of the shell to the emission spectrum. We explored the effects that a temperature lower than the ~100-500K proposed from infrared observations and a high degree of clumping can have on the derived physical properties of the unshocked material, such as its mass and density. We also compiled integrated radio flux density measurements, fit for the absorption processes that occur in the radio band, and considered their ect on the secular decline of the source. We find a mass in the unshocked ejecta of M=2.95+/-0.48M_{sun}_ for an assumed gas temperature of T=100K. This estimate is reduced for colder gas temperatures and, most significantly, if the ejecta are clumped.We measure the reverse shock to have a radius of 114+/-6" and be centred at 23:23:26, +58:48:54 (J2000).We also find that a decrease in the amount of mass in the unshocked ejecta (as more and more material meets the reverse shock and heats up) cannot account for the observed low-frequency behaviour of the secular decline rate. To reconcile our low-frequency absorption measurements with models that reproduce much of the observed behaviour in Cas A and predict little mass in the unshocked ejecta, the ejecta need to be very clumped or the temperature in the cold gas needs to be low (~10K). Both of these options are plausible and can together contribute to the high absorption value that we find.
- ID:
- ivo://CDS.VizieR/J/ApJ/456/234
- Title:
- Cas A radio knots spectral indices
- Short Name:
- J/ApJ/456/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined the synchrotron spectral indices of 304 compact radio knots in the supernova remnant Cassiopeia A. A comparison of these data with the dynamical and brightness properties of these knots tabulated by Anderson & Rudnick (Cat. <J/ApJ/441/307>) indicates that spectral index shows a significant correlation with projected radius from the center of the remnant. Spectrally flat knots reside in a shell coincident with the bright radio ring, while steeper knots occupy a shell coincident with the diffuse radio plateau surrounding the ring. To a lesser extent, we find spectral index to be correlated also with the radio brightness of the knot, in the sense that brighter knots tend to have steeper spectra. No significant correlation is found between spectral index and knot deceleration or rate of brightness change. As the synchrotron spectral index traces the distribution of energy among relativistic particle populations, we use these results to study the nature of particle acceleration mechanisms active in Cas A. Given the dual shell nature of the spectral index distribution in Cas A and the lack of strong correlation between spectral index and dynamical properties of the knots, we conclude that radio-bright compact features are not sites of currently active particle acceleration in Cas A. This conclusion is in agreement with models of supersonic gaseous bullets constructed by Jones, Kang, & Tregillis (1994ApJ...432..194J). In these models, the marked synchrotron brightening which accompanies bullet deceleration is due primarily to preexisting relativistic particles radiating in rapidly amplifying shear-layer magnetic fields, rather than a large infusion of new relativistic particles accelerated in situ. Spectral variations between compact features in Cas A are more likely to reflect modulations in the background particle energy spectra within the remnant, perhaps instilled by temperature variations in the underlying thermal material. This interpretation requires that the diffuse synchrotron emission show the same spectral variations as seen in compact features; preliminary indications suggest that this is the case.
