An X-ray study of the SNR G344.7-0.1 and the central object CXOU J170357.8-414302 (original) (raw)
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Optical and infrared observations of the X-ray source 1WGA J1713.4–3949 in the G347.3-0.5 SNR
Astronomy and Astrophysics, 2008
Context. X-ray observations unveiled the existence of enigmatic point-like sources at the centre of young supernova remnants (SNRs). These sources, dubbed Central Compact Objects (CCOs), are thought to be neutron stars formed by the supernova explosion. However, their multi-wavelength phenomenology is surprisingly different from that of most young neutron stars. Aims. The aim of this work is to understand the nature of the CCO 1WGA J1713.4−3949 in the G347.3-0.5 SNR, through deep optical and IR observations, the first ever performed for this source. Methods. By exploiting its derived Chandra X-ray position we carried out optical (BVI) observations with the NTT and Adaptive Optics IR (JHKs) observations with the VLT. Results. We detected two faint (I≈ 23.5, I≈ 24.3.) patchy objects in the NTT images, close to the Chandra error circle. They were clearly resolved in our VLT images which unveiled a total of six candidate counterparts (17.8 < H < 20.3) with quite red colours (H-Ks∼0.6). If they are stars, none of them can be associated with 1WGA J1713.4−3949 for the most likely values of distance and hydrogen column density. The identification of the faintest candidate with the neutron star itself can not be firmly excluded, while the identification with a fallback disk is ruled out by its non-detection in the I band. No other candidates are detected down to B∼ 26, V∼ 26.2, I∼ 24.7, H∼21.3 and K∼20.5. Conclusions. Our high-resolution IR imaging of unveiled a few objects close/within the Chandra X-ray position of 1WGA J1713.4−3949. However, at present none of them can be firmly identified as its likely counterpart.
The compact central source in the RX J0852-4622 supernova remnant
2001
The central region of the recently discovered supernova remnant RX J0852.0-4622 was observed with the ACIS detector aboard the Chandra X-ray Observatory. We found only one relatively bright source, about 4' north of the SNR center, with a flux of sim2times10−12\sim 2\times 10^{-12}sim2times10−12 erg s$^{-1}$ cm$^{-2}$ in the 0.5--10 keV band. The position of this point-like source, CXOU J085201.4-461753, rules out its association with the two bright stars in the field, HD 76060 and Wray 16-30. Observations of the field with the CTIO 0.9-m telescope show a star ($R\approx 17$, Bapprox19B\approx 19Bapprox19) at about 2\farcs4 from the nominal X-ray position. We consider association of this star with the X-ray source unlikely and estimate a limiting magnitude of the optical counterpart as Bge22.5B \ge 22.5Bge22.5 and Rge21.0R \ge 21.0Rge21.0. Based on the X-ray-to-optical flux ratio, we argue that the X-ray source is likely the compact remnant of the supernova explosion that created the RX J0852.0-4622 SNR. The observed X-ray spectrum of the source is softer than spectra of magnetospheric radiation of rotation-powered pulsars, but it is harder than spectra of cooling neutron stars emitting thermal radiation from the entire surface, similar to the central compact source of the Cas A SNR. We suggest that CXOU J085201.4-461753 belongs to the growing family of radio-quiet compact central sources, presumably neutron stars, recently discovered in a number of SNRs.
The (Re-)Discovery of G350.1-0.3: A Young, Luminous Supernova Remnant and Its Neutron Star
The Astrophysical Journal, 2008
We present an XMM-Newton observation of the long-overlooked radio source G350.1-0.3. The X-ray spectrum of G350.1-0.3 can be fit by a shocked plasma with two components: a high-temperature (1.5 keV) region with a low ionization time scale and enhanced abundances, plus a cooler (0.36 keV) component in ionization equilibrium and with solar abundances. The X-ray spectrum and the presence of non-thermal, polarized, radio emission together demonstrate that G350.1-0.3 is a young, luminous supernova remnant (SNR), for which archival H I and 12 CO data indicate a distance of 4.5 kpc. The diameter of the source then implies an age of only ≈ 900 years. The SNR's distorted appearance, small size and the presence of 12 CO emission along the SNR's eastern edge all indicate that the source is interacting with a complicated distribution of dense ambient material. An unresolved X-ray source, XMMU J172054.5-372652, is detected a few arcminutes west of the brightest SNR emission. The thermal X-ray spectrum and lack of any multi-wavelength counterpart suggest that this source is a neutron star associated with G350.1-0.3, most likely a "central compact object", as seen coincident with other young SNRs such as Cassiopeia A.
Discovery of a Compact X‐Ray Source in the LMC Supernova Remnant N23 withChandra
The Astrophysical Journal, 2006
An X-ray compact source was discovered with Chandra in a supernova remnant (SNR) N23, located in the Large Magellanic Cloud. The compact source (CXOU J050552.3−680141) is seen in only the hard band (> 2 keV) image of N23, while the soft band image (< 2 keV) shows diffuse emission of the SNR, with an extent of ∼ 60 ′′ × 80 ′′. The compact source is located at almost the center of N23, and there is no identifiable object for the source from previous observations at any other wavelength. The source spectrum is best explained by a power-law model with a photon index of Γ = 2.2 +0.5 −0.3 and an absorption-corrected luminosity of L x = 1.0 × 10 34 ergs s −1 in the 0.5-10 keV band for a distance of 50 kpc. Neither pulsation nor time variability of the source was detected with this observation with a time resolution of 3.2 sec. These results correspond with those of Hughes et al. (2006), who carried out analysis independently around the same time as our work. Based on information from the best-fit power-law model, we suggest that the source emission is most likely from a rotation-powered pulsar and/or a pulsar wind nebula. It is generally inferred that the progenitor of N23 is a core-collapsed massive star.
The X-Ray Properties of Five Galactic Supernova Remnants Detected by the Spitzer Glimpse Survey
The Astronomical Journal, 2014
We present a study of the X-ray properties of five Galactic supernova remnants (SNRs)-Kes 17 (G304.6+0.1), G311.5−0.3, G346.6−0.2, CTB 37A (G348.5+0.1) and G348.5−0.0-that were detected in the infrared by Reach et al. (2006) in an analysis of data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) that was conducted by the Spitzer Space Telescope. We present and analyze archival ASCA observations of Kes 17, G311.5−0.3 and G346.6−0.2, archival XMM-Newton observations of Kes 17, CTB 37A and-2-G348.5−0.0 and an archival Chandra observation of CTB 37A. All of the SNRs are clearly detected in the X-ray possibly except for G348.5−0.0. Our study reveals that the four detected SNRs all feature center-filled X-ray morphologies and that the observed emission from these sources is thermal in all cases. We argue that these SNRs should be classified as mixed-morphology SNRs (MM SNRs): our study strengthens the correlation between MM SNRs and SNRs interacting with molecular clouds and suggests that the origin of mixed-morphology SNRs may be due to the interactions between these SNRs and adjacent clouds. Our ASCA analysis of G311.5−0.3 reveals for the first time X-ray emission from this SNR: the X-ray emission is center-filled within the radio and infrared shells and thermal in nature (kT ∼ 0.98 keV), thus motivating its classification as an MM SNR. We find considerable spectral variations in the properties associated with the plasmas of the other X-ray-detected SNRs, such as a possible overabundance of magnesium in the plasma of Kes 17. Our new results also include the first detailed spatially-resolved spectroscopic study of CTB 37A using Chandra as well as a spectroscopic study of the discrete X-ray source CXOU J171428.5−383601, which may be a neutron star associated with CTB 37A. Finally, we also estimate such properties as electron density n e , radiative age t rad and swept-up mass M X for each of the four X-ray-detected SNRs. Each of these values are comparable to archetypal mixed-morphology SNRs like 3C 391 and W44. In an analysis of the spectrum of Kes 17, we did not find evidence of over-ionization unlike other archetypal mixed-morphology SNRs like W28 and W44.
XMM‐Newton , Chandra , and CGPS observations of the Supernova Remnants G85.4+0.7 and G85.9−0.6
The Astrophysical Journal, 2008
We present an XMM-Newton detection of two low radio surface brightness SNRs, G85.4+0.7 and G85.9−0.6, discovered with the Canadian Galactic Plane Survey (CGPS). High-resolution XMM-Newton images revealing the morphology of the diffuse emission, as well as discrete point sources, are presented and correlated with radio and Chandra images. The new data also permit a spectroscopic analysis of the diffuse emission regions, and a spectroscopic and timing analysis of the point sources. Distances have been determined from H I and CO data to be 3.5 ± 1.0 kpc for SNR G85.4+0.7 and 4.8 ± 1.6 kpc for SNR G85.9−0.6.
The Astrophysical Journal, 2005
We report the discovery of 105-ms X-ray pulsations from the compact central object (CCO) in the supernova remnant Kes 79 using data acquired with the Newton X-Ray Multi-Mirror Mission. Two observations of the pulsar taken 6 days apart yield an upper limit on its spin-down rate oḟ P < 7 × 10 −14 s s −1 and no evidence for binary orbital motion. The implied energy loss rate iṡ E < 2 × 10 36 ergs s −1 , surface magnetic field strength is B p < 3 × 10 12 G, and spin-down age is τ > 24 kyr. The latter exceeds the remnant's estimated age, suggesting that the pulsar was born spinning near its current period. The X-ray spectrum of PSR J1852+0040 is best characterized by a blackbody model of temperature kT BB = 0.44±0.03 keV, radius R BB ≈ 0.9 km, and L bol = 3.7×10 33 ergs s −1 at d = 7.1 kpc. The sinusoidal light curve is modulated with a pulsed fraction of > 45%, suggestive of a small hot spot on the surface of the rotating neutron star. The lack of a discernible pulsar wind nebula is consistent with an interpretation of PSR J1852+0040 as a rotation-powered pulsar whose spin-down luminosity falls below the empirical threshold for generating bright wind nebulae,Ė c ≈ 4 × 10 36 ergs s −1. The age discrepancy implies that itsĖ has always been belowĖ c , perhaps a distinguishing property of the CCOs. Alternatively, the X-ray spectrum of PSR J1852+0040 suggests a low-luminosity AXP, but the weak inferred B p field is incompatible with a magnetar theory of its X-ray luminosity. So far, we cannot exclude accretion from a fall-back disk. The ordinary spin parameters discovered from PSR J1852+0040 highlight the difficulty that existing theories of isolated neutron stars have in explaining the high luminosities and temperatures of CCO thermal X-ray spectra.
The Astrophysical Journal, 2007
We present X-ray, infrared and radio observations of the field centered on X-ray source 1E 1547.0-5408 in the Galactic Plane. Analysis of a new Chandra observation of this source shows it is unresolved at arc-second resolution, and analysis of a new XMM observation shows that its X-ray spectrum is best described by an absorbed power-law and blackbody model. A comparison of the X-ray flux observed from 1E 1547.0-5408 between 1980 and 2006 by Einstein, ASCA, XMM, and Chandra reveals that its absorbed 0.5-10 keV X-ray flux decreased significantly during this period, from ∼ 2×10 −12 ergs cm −2 s −1 to ∼ 3 × 10 −13 ergs cm −2 . No pulsations in the X-ray emission from 1E 1547.0-5408 were observed during the most recent XMM observation, which allows us to put a 5σ confidence upper limit of 14% for the 0.5-10 keV peak-to-peak pulsed fraction (for sinusoidal pulses with periods slower than 1.8s). A near-infrared observation of this field shows a source with magnitude K s = 15.9 ± 0.2 near the position of 1E 1547.0-5408, but the implied X-ray to infrared flux ratio indicates the infrared emission is most likely from an unrelated field source, allowing us to limit the IR magnitude of any counterpart to 1E 1547.0-5408 to 17.5. Archival radio observations reveal that 1E 1547.0-5408 sits at the center of a faint, small (4 ′ diameter) radio shell, G327.24-0.13, which is possibly a previously unidentified supernova remnant. The X-ray properties of 1E 1547.0-5408 suggest that this source is a magnetar -a young neutron star whose X-ray emission is powered by the decay of its extremely strong magnetic field, B ∼ 10 14−15 G. The spatial coincidence between this source and G327.24-0.13 suggests that 1E 1547.0-5408 is associated with a young supernova remnant, supporting a neutron star interpretation. Additional observations are needed to confirm the nature of both 1E 1547.0-5408 and G327.24-0.13, and to determine whether these sources are physically associated. If confirmed, this pair will be an important addition to the small number of known associations between magnetars and supernova remnants.
Detailed study of SNR G306.3−0.9 usingXMM-NewtonandChandraobservations
Astronomy and Astrophysics, 2016
Aims. We aim to study the spatial distribution of the physical and chemical properties of the X-ray emitting plasma of the supernova remnant (SNR) G306.3−0.9 in detail to obtain constraints on its ionization stage, the progenitor supernova explosion, and the age of the remnant. Methods. We used combined data from XMM-Newton and Chandra observatories to study the X-ray morphology of G306.3−0.9 in detail. A spatially resolved spectral analysis was used to obtain physical and geometrical parameters of different regions of the remnant. Spitzer infrared observations, available in the archive, were also used to constrain the progenitor supernova and study the environment in which the remnant evolved. Results. The X-ray morphology of the remnant displays a non-uniform structure of semi-circular appearance, with a bright southwest region and very weak or almost negligible X-ray emission in its northern part. These results indicate that the remnant is propagating in a non-uniform environment as the shock fronts are encountering a high-density medium, where enhanced infrared emission is detected. The X-ray spectral analysis of the selected regions shows distinct emission-line features of several metal elements, confirming the thermal origin of the emission. The X-ray spectra are well represented by a combination of two absorbed thermal plasma models: one in equilibrium ionization (VAPEC) with a mean temperature of ∼0.19 keV, and another out of equilibrium ionization (VNEI) at a higher temperature of ∼1.1 or 1.6-1.9 keV. For regions located in the northeast, central, and southwest part of the SNR, we found elevated abundances of Si, S, Ar, Ca, and Fe, typical of ejecta material. The outer regions located northwest and south show values of the abundances above solar but lower than to those found in the central regions. This suggests that the composition of the emitting outer parts of the SNR is a combination of ejecta and shocked material of the interstellar medium. The comparison between the S/Si, Ar/Si, and Ca/Si abundances ratios (1.75, 1.27, and 2.72 in the central region, respectively), favor a Type Ia progenitor for this remnant, a result that is also supported by an independent morphological analysis using the X-ray and 24 µm IR data.
Discovery of thermal X-ray emission in the supernova remnant G337.8-0.1 (Kes 41)
Astronomy and Astrophysics, 2008
Aims. We report here on the first detection at X-ray wavelengths of the Supernova Remnant (SNR) G337.8−0.1, carried out with the XMM-Newton Observatory. Methods. Using the X-ray observations, we studied the X-ray morphology of the remnant at different energy ranges, analysed the spectral properties and investigated a possible variable behavior. Results. The SNR shows a diffuse filled-center structure in the X-ray region with an absence of a compact source in its center. We find a high column density of N H > 6.9×10 22 cm −2 , which supports a relatively distant location (d ≥ 7 kpc). The X-ray spectrum exhibits emission lines, indicating that the X-ray emission has a thin thermal plasma origin, and is well represented by a non-equilibrium ionization (NEI) plasma model. The X-ray characteristics and well-known radio parameters show that G337.8−0.1 belongs to the emerging class of mixed-morphology (MM) SNRs.