Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSupernova Remnants in the AKARI IRC Survey of the Large Magellanic Cloud
212
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present the near- to mid-infared study of supernova remnants (SNRs) using the AKARI IRC Survey of the Large Magellanic Cloud (LMC). The LMC survey observed about a 10 square degree area of the LMC in five bands centered at 3, 7, 11, 15, and 24 micron using the Infrared Camera (IRC) aboard AKARI. The number of SNRs in the survey area is 21, which is about a half of the known LMC SNRs. We systematically examined the AKARI images and identified eight SNRs with distinguishable infrared emission. All of them were detected at $gtrsim 10$ micron and some at 3 and 7 micron, too. We present their AKARI images and fluxes. In the 11/15 micron versus 15/24 micron color-color diagram, the SNRs appear to be aligned along a modified blackbody curve, representing thermal emission from dust at temperatures between 90 and 190 K. There is a good correlation between the 24 micron and X-ray fluxes of the SNRs. It was also found that there is a good correlation between the 24 micron and radio fluxes even if there is no direct physical connection between them. We considered the origin of the detected mid-infrared emission in individual SNRs. We conclude that the mid-infrared emissions in five SNRs that show morphologies similar to the X-rays are dominated by thermal emission from hot dust heated by X-ray emitting plasma. Their 15/24 micron color temperatures are generally higher than the Spitzer 24/70 micron color temperatures, which suggests that a single-temperature dust model cannot describe the full spectral energy distribution (SED) of the SNRs. It also implies that our understanding of the full SED is essential for estimating the dust destruction rate of grains by SNR shocks.
rate research
Read More
We observed an area of 10 deg^2 of the Large Magellanic Cloud using the Infrared Camera on board AKARI. The observations were carried out using five imaging filters (3, 7, 11, 15, and 24 micron) and a dispersion prism (2 -- 5 micron, $lambda / Deltalambda$ $sim$ 20) equipped in the IRC. This paper describes the outline of our survey project and presents some initial results using the imaging data that detected over 5.9x10^5 near-infrared and 6.4x10^4 mid-infrared point sources. The 10 $sigma$ detection limits of our survey are about 16.5, 14.0, 12.3, 10.8, and 9.2 in Vega-magnitude at 3, 7, 11, 15, and 24 micron, respectively. The 11 and 15 micron data, which are unique to AKARI IRC, allow us to construct color-magnitude diagrams that are useful to identify stars with circumstellar dust. We found a new sequence in the color-magnitude diagram, which is attributed to red giants with luminosity fainter than that of the tip of the first red giant branch. We suggest that this sequence is likely to be related to the broad emission feature of aluminium oxide at 11.5 micron. The 11 and 15 micron data also indicate that the ([11] - [15]) micron color of both oxygen-rich and carbon-rich red giants once becomes blue and then turns red again in the course of their evolution, probably due to the change in the flux ratio of the silicate or silicon carbide emission feature at 10 or 11.3 micron to the 15 micron flux.
It has often been suggested that supernova remnants (SNRs) can trigger star formation. To investigate the relationship between SNRs and star formation, we have examined the known sample of 45 SNRs in the Large Magellanic Cloud to search for associated young stellar objects (YSOs) and molecular clouds. We find seven SNRs associated with both YSOs and molecular clouds, three SNRs associated with YSOs but not molecular clouds, and eight SNRs near molecular clouds but not associated with YSOs. Among the 10 SNRs associated with YSOs, the association between the YSOs and SNRs can be either rejected or cannot be convincingly established for eight cases. Only two SNRs have YSOs closely aligned along their rims; however, the time elapsed since the SNR began to interact with the YSOs natal clouds is much shorter than the contraction timescales of the YSOs, and thus we do not see any evidence of SNR-triggered star formation in the LMC. The 15 SNRs that are near molecular clouds may trigger star formation in the future when the SNR shocks have slowed down to <45 km/s. We discuss how SNRs can alter the physical properties and abundances of YSOs.
We present a new optical sample of three Supernova Remnants and 16 Supernova Remnant (SNR) candidates in the Large Magellanic Cloud(LMC). These objects were originally selected using deep H$alpha$, [SII] and [OIII] narrow-band imaging. Most of the newly found objects are located in less dense regions, near or around the edges of the LMCs main body. Together with previously suggested MCSNR J0541-6659, we confirm the SNR nature for two additional new objects: MCSNR J0522-6740 and MCSNRJ0542-7104. Spectroscopic follow-up observations for 12 of the LMC objects confirm high [SII]/H$alpha$ a emission-line ratios ranging from 0.5 to 1.1. We consider the candidate J0509-6402 to be a special example of the remnant of a possible Type Ia Supernova which is situated some 2$^circ$ ($sim 1.75$kpc) north from the main body of the LMC. We also find that the SNR candidates in our sample are significantly larger in size than the currently known LMC SNRs by a factor of $sim 2$. This could potentially imply that we are discovering a previously unknown but predicted, older class of large LMC SNRs that are only visible optically. Finally, we suggest that most of these LMC SNRs are residing in a very rarefied environment towards the end of their evolutionary span where they become less visible to radio and X-ray telescopes.
We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in the LMC. Using primarily XMM-Newton, we conduct a systematic spectral analysis of LMC SNRs to gain new insights on their evolution and the interplay with their host galaxy. We combined all the archival XMM observations of the LMC with those of our Very Large Programme survey. We produced X-ray images and spectra of 51 SNRs, out of a list of 59. Using a careful modelling of the background, we consistently analysed all the X-ray spectra and measure temperatures, luminosities, and chemical compositions. We investigated the spatial distribution of SNRs in the LMC and the connection with their environment, characterised by various SFHs. We tentatively typed all LMC SNRs to constrain the ratio of core-collapse to type Ia SN rates in the LMC. We compared the X-ray-derived column densities to HI maps to probe the three-dimensional structure of the LMC. This work provides the first homogeneous catalogue of X-ray spectral properties of LMC SNRs. It offers a complete census of LMC SNRs exhibiting Fe K lines (13% of the sample), or revealing contribution from hot SN ejecta (39%). Abundances in the LMC ISM are found to be 0.2-0.5 solar, with a lower [$alpha$/Fe] than in the Milky Way. The ratio of CC/type Ia SN in the LMC is $N_{mathrm{CC}}/N_{mathrm{Ia}} = 1.35(_{-0.24}^{+0.11})$, lower than in local SN surveys and galaxy clusters. Comparison of X-ray luminosity functions of SNRs in Local Group galaxies reveals an intriguing excess of bright objects in the LMC. We confirm that 30 Doradus and the LMC Bar are offset from the main disc of the LMC, to the far and near sides, respectively. (abridged)
We present first results from an extensive survey of Magellanic Clouds supernova remnants (SNRs) with the Spitzer Space Telescope. We describe IRAC and MIPS imaging observations at 3.6, 4.5, 5.8, 8, 24, and 70 microns of four Balmer-dominated Type Ia SNRs in the Large Magellanic Cloud (LMC): DEM L71 (0505-67.9), 0509--67.5, 0519--69.0, and 0548-70.4. None was detected in the four short-wavelength IRAC bands, but all four were clearly imaged at 24 microns, and two at 70 microns. A comparison of these images to Chandra broadband X-ray images shows a clear association with the blast wave, and not with internal X-ray emission associated with ejecta. Our observations are well described by 1-D shock models of collisionally heated dust emission, including grain size distributions appropriate for the LMC, grain heating by collisions with both ions and electrons, and sputtering of small grains. Model parameters are constrained by X-ray, optical, and far-ultraviolet observations. Our models can reproduce observed 70/24 micron flux ratios only by including sputtering, destroying most grains smaller than 0.03-0.04 microns in radius. We infer total dust masses swept up by the SNR blast waves, before sputtering, of order 0.01 solar masses, several times less than those implied by a dust/gas mass ratio of 0.3 percent as often assumed for the LMC. Substantial dust destruction has implications for gas-phase abundances.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
