-
[show abstract]
[hide abstract]
ABSTRACT: Context: We study the X-ray emission of the Galactic supernova remnant (SNR)
CTB 109 (G109.1-1.0), which is well-known for its enigmatic half-shell
morphology both in radio and in X-rays and is associated with the anomalous
X-ray pulsar (AXP) 1E2259+586. Aims: We want to understand the origin of the
X-ray bright feature inside the SNR called the Lobe and the details of the
interaction of the SNR shock wave with the ambient interstellar medium (ISM).
Methods: The Lobe and the northeastern part of the SNR were observed with
Chandra ACIS-I. We analysed the spectrum of the X-ray emission by dividing the
entire observed emission into small regions. The X-ray emission is best
reproduced with one-component or two-component non-equilibrium ionisation
models depending on the position. In the two-component model one emission
component represents the shocked ISM and the other the shocked ejecta. Results:
We detect enhanced element abundances, in particular for Si and Fe, in and
around the Lobe. There is one particular region next to the Lobe with a high Si
abundance of 3.3 (2.6 - 4.0) times the solar value. This is the first,
unequivocal detection of ejecta in CTB 109. Conclusions: The new Chandra data
confirm that the Lobe was created by the interaction of the SNR shock and the
supernova ejecta with dense and inhomogeneous medium in the environment of SNR
CTB 109. The newly calculated age of the SNR is t ~ 1.4 x 10^4 yr.
02/2013;
-
[show abstract]
[hide abstract]
ABSTRACT: We present the analysis of supernova remnants (SNRs) and candidates in M31
identified in the XMM-Newton large programme survey of M31. SNRs are among the
bright X-ray sources in a galaxy. They are good indicators of recent star
formation activities of a galaxy and of the interstellar environment in which
they evolve. By combining the X-ray data of sources in M31 with optical data as
well as with optical and radio catalogues, we aim to compile a complete,
revised list of SNRs emitting X-rays in M31 detected with XMM-Newton, study
their luminosity and spatial distribution, and understand the X-ray spectrum of
the brightest SNRs. We analysed the X-ray spectra of the twelve brightest SNRs
and candidates using XMM-Newton data. The four brightest sources allowed us to
perform a more detailed spectral analysis and the comparison of different
models to describe their spectrum. For all M31 large programme sources we
searched for optical counterparts on the Ha, [Sii], and [Oiii] images of the
Local Group Galaxy Survey. We confirm 21 X-ray sources as counterparts of known
SNRs. In addition, we identify five new X-ray sources as X-ray and optically
emitting SNRs. Seventeen sources are no longer considered as SNR candidates. We
have thus created a list of 26 X-ray SNRs and 20 candidates in M31 based on
their X-ray, optical, and radio emission, which is the most recent complete
list of X-ray SNRs in M31. The brightest SNRs have X-ray luminosities of up to
8 x 10^36 erg/s in the 0.35 - 2.0 keV band.
06/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: Aims: We study the diffuse X-ray emission observed in the field of view of
the pulsar B 0540-69 in the Large Magellanic Cloud (LMC) by XMM-Newton. We want
to understand the nature of this soft diffuse emission, which coincides with
the superbubble in the HII region N 158, and improve our understanding of the
evolution of superbubbles. Methods: We analyse the XMM-Newton spectra of the
diffuse emission. Using the parameters obtained from the spectral fit, we
perform calculations of the evolution of the superbubble. The mass loss and
energy input rates are based on the initial mass function (IMF) of the observed
OB association inside the superbubble. Results: The analysis of the spectra
shows that the soft X-ray emission arises from hot shocked gas surrounded by a
thin shell of cooler, ionised gas. We show that the stellar winds alone cannot
account for the energy inside the superbubble, but the energy release of 2 - 3
supernova explosions in the past ~1 Myr provides a possible explanation.
Conclusions: The combination of high sensitivity X-ray data, allowing spectral
analysis, and analytical models for superbubbles bears the potential to reveal
the evolutionary state of interstellar bubbles, if the stellar content is
known.
10/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: The Chandra ACIS Survey of M33 (ChASeM33) has acquired seven fields of ACIS data covering M33 with 200 ks of exposure in each field. A catalog from the first 10 months of data, along with archival Chandra observations dating back to the year 2000, is currently available. We have searched these data for transient sources that are measured to have a 0.35-8.0 keV unabsorbed luminosity of at least 4 × 1035 ergs s−1 in one epoch and are not detected in another epoch. This set of the survey data has yielded seven such sources, including one previously known supersoft source. We analyzed XMM-Newton data from the archive distributed over the years 2000-2003 to search for recurrent outbursts and to get a spectrum for the supersoft transient. We find only one recurrent transient in our sample. The X-ray spectra, light curves, and optical counterpart candidates of two of the other sources suggest that they are high-mass X-ray binaries. Archival Spitzer photometry and high X-ray absorption suggest that one of the sources is a highly variable background active galactic nucleus. The other three sources are more difficult to classify. The bright transient population of M33 appears to contain a large fraction of high-mass X-ray binaries compared with the transient populations of M31 and the Galaxy, reflecting the later morphology of M33.
The Astrophysical Journal 12/2008; 680(2):1120. · 6.02 Impact Factor
-
Paul P. Plucinsky,
Benjamin Williams,
Knox S. Long,
Terrance J. Gaetz, Manami Sasaki,
Wolfgang Pietsch,
Ralph Tüllmann,
Randall K. Smith,
William P. Blair,
David Helfand, [......],
Richard J. Edgar,
Parviz Ghavamian,
Jonathan Grindlay,
Frank Haberl,
Robert Kirshner,
Kip Kuntz,
Tsevi Mazeh,
Thomas G. Pannuti,
Avi Shporer,
and David A. Thilker
[show abstract]
[hide abstract]
ABSTRACT: We present an overview of the Chandra ACIS Survey of M33 (ChASeM33): A Deep Survey of the Nearest Face-on Spiral Galaxy. The 1.4 Ms survey covers the galaxy out to R ≈ 18'(≈ 4 kpc) . These data provide the most intensive, high spatial resolution assessment of the X-ray source populations available for the confused inner regions of M33. Mosaic images of the ChASeM33 observations show several hundred individual X-ray sources as well as soft diffuse emission from the hot interstellar medium. Bright, extended emission surrounds the nucleus and is also seen from the giant H II regions NGC 604 and IC 131. Fainter extended emission and numerous individual sources appear to trace the inner spiral structure. The initial source catalog, arising from ~2/3 of the expected survey data, includes 394 sources significant at the 3 σ confidence level or greater, down to a limiting luminosity (absorbed) of ~1.6 × 1035 ergs s−1 (0.35-8.0 keV). The hardness ratios of the sources separate those with soft, thermal spectra such as supernova remnants from those with hard, nonthermal spectra such as X-ray binaries and background active galactic nuclei. Emission extended beyond the Chandra point-spread function is evident in 23 of the 394 sources. Cross-correlation of the ChASeM33 sources against previous catalogs of X-ray sources in M33 results in matches for the vast majority of the brighter sources and shows 28 ChASeM33 sources within 10'' of supernova remnants identified by prior optical and radio searches. This brings the total number of such associations to 31 out of 100 known supernova remnants in M33.
The Astrophysical Journal Supplement Series 12/2008; 174(2):366. · 13.46 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We present Far Ultraviolet Spectroscopic Explorer (FUSE) and X-Ray Multi-Mirror Mission (XMM-Newton) data for the reverse shock of the O-rich supernova remnant (SNR) 1E 0102.2-7219 in the Small Magellanic Cloud (SMC). The FUSE observations cover three regions with significantly different optical [O III] intensities, all associated with the relatively bright part of the X-ray ring. Emission lines of O VI λλ1032, 1038 are clearly detected in the FUSE spectra. The XMM-Newton EPIC MOS 1/2 spectra are dominated by strong emission lines of O, Ne, and Mg. By combining the O VI doublet emission with the O VII triplet and O VIII Lyα fluxes from the X-ray spectra and assuming a nonequilibrium ionization (NEI) model with a single ionization timescale for the spectra, we find an increase of the ionization timescale τ from north (τ ≈ 0.6 × 1011 s cm-3) to southeast (τ ≈ 2 × 1011 s cm-3). This is indicative of increasing density in the X-ray-bright ring, in good agreement with the optical [O III] emission, which is strongest in the southeast. However, if we assume a plane-parallel shock model with a distribution of ionization timescales, the O VI emission appears to be inconsistent with O VII and O VIII in X-rays. The analysis of the total X-ray spectra shows that there is no consistent set of values for the temperature and ionization timescale that can explain the observed line ratios for O, Ne, and Mg. This would be consistent with a structured distribution of the ejecta, as the O, Ne, and Mg would have interacted with the reverse shock at different times.
The Astrophysical Journal 12/2008; 642(1):260. · 6.02 Impact Factor
-
Terrance J. Gaetz,
William P. Blair,
John P. Hughes,
P. Frank Winkler,
Knox S. Long,
Thomas G. Pannuti,
Benjamin Williams,
Richard J. Edgar,
Parviz Ghavamian,
Paul P. Plucinsky, Manami Sasaki,
Robert P. Kirshner,
Miguel Avillez,
and Dieter Breitschwerdt
[show abstract]
[hide abstract]
ABSTRACT: We present and interpret new X-ray data for M33SNR 21, the brightest X-ray supernova remnant (SNR) in M33. The SNR is in seen projection against (and appears to be interacting with) the bright H II region NGC 592. Data for this source were obtained as part of the Chandra ACIS Survey of M33 (ChASeM33) Very Large Project. The nearly on-axis Chandra data resolve the SNR into a ~5'' diameter (20 pc at our assumed M33 distance of 817 ± 58 kpc) slightly elliptical shell. The shell is brighter in the east, which suggests that it is encountering higher density material in that direction. The optical emission is coextensive with the X-ray shell in the north, but extends well beyond the X-ray rim in the southwest. Modeling the X-ray spectrum with an absorbed sedov model yields a shock temperature of 0.46 keV, with an ionization timescale of net = 2.1 × 1012 cm-3 s and half-solar abundances (0.45). Assuming Sedov dynamics gives an average preshock H density of 1.7 ± 0.3 cm-3. The dynamical age estimate is 6500 ± 600 yr, while the best-fit net value and derived ne gives 8200 ± 1700 yr; the weighted mean of the age estimates is 6700 ± 600 yr. We estimate an X-ray luminosity (0.25-4.5 keV) of (1.2 ± 0.2) × 1037 ergs s-1 (absorbed), and (1.7 ± 0.3) × 1037 ergs s-1 (unabsorbed), in good agreement with the recent XMM-Newton determination. No significant excess hard emission was detected; the luminosity 1.2 × 1035 ergs s-1 (2-8 keV) for any hard point source.
The Astrophysical Journal 12/2008; 663(1):234. · 6.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We present the analysis of the X-ray Multimirror Mission (XMM-Newton) European Photon Imaging Camera (EPIC) data of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0). CTB 109 is associated with the anomalous X-ray pulsar (AXP) 1E 2259+586 and has an unusual semicircular morphology in both the X-ray and the radio and an extended X-ray bright interior region known as the "Lobe." The deep EPIC mosaic image of the remnant shows no emission toward the west where a giant molecular cloud complex is located. No morphological connection between the Lobe and the AXP is found. We find remarkably little spectral variation across the remnant given the large intensity variations. All spectra of the shell and the Lobe are well fitted by a single-temperature nonequilibrium ionization model for a collisional plasma with solar abundances [kT ≈ 0.5-0.7 keV, τ = ne dt ≈ (1-4) × 1011 s cm-3, NH ≈ (5-7) × 1021 cm-2]. There is no indication of nonthermal emission in the Lobe or the shell. We conclude that the Lobe originated from an interaction of the SNR shock wave with an interstellar cloud. Applying the Sedov solution for the undisturbed eastern part of the SNR and assuming full equilibration between the electrons and ions behind the shock front, the SNR shock velocity is derived as vs = 720 ± 60 km s-1, the remnant age as t = (8.8 ± 0.9) × 103d3 yr, the initial energy as E0 = (7.4 ± 2.9) × 1050d ergs, and the preshock density of the nuclei in the ambient medium as n0 = (0.16 ± 0.02)d cm-3, at an assumed distance of D = 3.0d3 kpc. Assuming that CTB 109 and 1E 2259+586 are associated, these values constrain the age and the environment of the progenitor of the SNR and the pulsar.
The Astrophysical Journal 12/2008; 617(1):322. · 6.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We present results of a search for supernova remnants (SNRs) in archival Chandra images of M33. We have identified X-ray SNRs by comparing the list of Chandra X-ray sources in M33 with tabulations of SNR candidates identified from (1) elevated [S II]/Hα ratios in the optical and (2) radio spectral indices. In addition, we have searched for optical counterparts to soft sources in the Chandra images and X-ray SNR candidates identified in the XMM-Newton survey of M33. Of the 98 optically known SNRs in M33, 22 have been detected at >3 σ level in the soft band (0.35–1.1 keV). At least four of these SNR candidates are spatially extended based on a comparison of the data to simulated images of point sources. Aside from the optically matching SNRs, we have found one soft X-ray source in M33 that exhibits no optical emission and is coincident with a known radio source. The radio spectral index of this source is consistent with particle acceleration in shocks, leading us to suggest that it is a nonradiative SNR. We have also found new optical counterparts to two soft X-ray SNRs in M33. These counterparts exhibit enhanced [S II]/Hα ratios characteristic of radiative shocks. Pending confirmation from optical spectroscopy, the identification of these two optical counterparts increases the total number of known optically emitting SNRs in M33 to 100. This brings the total number of identified SNRs with X-ray counterparts, including those exclusively detected by the XMM-Newton survey of M33, to 37 SNRs. We find that while there are a similar number of confirmed X-ray SNRs in M33 and the LMC with X-ray luminosities in excess of 1035 ergs s-1, nearly 40% of the LMC SNRs are brighter than 1036 ergs s-1, while only 13% of the M33 sample exceed this luminosity. Including X-ray SNR candidates from the XMM-Newton survey (objects lacking optical counterparts) increases the fraction of M33 SNRs brighter than 1036 ergs s-1 to 22%, still only half the LMC fraction. The differences in luminosity distributions cannot be fully explained by uncertainty in spectral model parameters and are not fully accounted for by abundance differences between the galaxies.
The Astronomical Journal 12/2007; 130(2):539. · 4.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the detection of molecular clouds around the X-ray bright interior feature in the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0). This feature, called the Lobe, has been previously suggested to be the result of an interaction of the SNR shock wave with a molecular cloud complex. We present new high resolution X-ray data from the Chandra X-ray Observatory and new high resolution CO data from the Five College Radio Observatory which show the interaction region with the cloud complex in greater detail. The CO data reveal three clouds around the Lobe in the velocity interval -57 < v < -52 km s^-1. The velocity profiles of 12CO at various parts of the east cloud are well fit with a Gaussian; however, at the position where the CO cloud and the Lobe overlap, the velocity profile has an additional component towards higher negative velocities. The molecular hydrogen density in this part of the cloud is relatively high (N_H2 = 1.9 x 10^20 cm^-2), whereas the foreground absorption in X-rays (N_H = 4.5 x 10^21 cm^-2), obtained from Chandra data, is lower than in other parts of the cloud and in the north and south cloud. These results indicate that this cloud has been hit by the SNR blast wave on the western side, forming the bright X-ray Lobe. Comment: Accepted for publication in ApJL. 3 figures
04/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: We present FUSE and XMM-Newton data for the reverse shock of the O-rich SNR 1E0102.2-7219 in the SMC. The FUSE observations cover three regions with significantly different optical [O III] intensities, all associated with the relatively bright part of the X-ray ring. Emission lines of O VI 1032, 1038 are clearly detected in the FUSE spectra. By combining this O VI doublet emission with the O VII triplet and O VIII Lyalpha fluxes from the XMM-Newton spectra and assuming a non-equilibrium ionization model with a single ionization timescale for the spectra, we are able to find a narrow range of temperatures and ionization timescales that are consistent with the respective line ratios. However, if we assume a plane-parallel shock model with a distribution of ionization timescales, the O VI emission appears to be inconsistent with O VII and O VIII in X-rays. We also analyze the total XMM-Newton EPIC-MOS 1/2 spectra for the three regions. The X-ray spectra are dominated by strong emission lines of O, Ne, and Mg, however, we detect an emission component that accounts for 14 - 25% of the flux and can be attributed to shocked ISM. We find that there is no consistent set of values for the temperature and ionization timescale which can explain the observed line ratios for O, Ne, and Mg. This would be consistent with a structured distribution of the ejecta as the O, Ne, Mg would have interacted with the reverse shock at different times. Comment: 28 pages, 5 figues, Fig. 1 as JPEG. To be published in ApJ (01 May 2006, v. 642, 1 issue)
02/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: Since supernova remnants (SNRs) are believed to be the primary sources of Galactic cosmic rays (CRs), their distribution in galaxies is an important basis for modelling and understanding the distribution of the CRs and their γ-ray spectrum. We analysed the radial surface density of X-ray and radio selected SNRs in the Large Magellanic Cloud (LMC) and M 33. Both in X-rays and in radio, the surface densities of the SNRs are in excellent agreement in both galaxies, showing an exponential decay in radius. The results were compared to the SNR distribution in the spiral galaxies M 31 and NGC 6946 as well. The radial scale length of the distribution is
\frac1 4 \frac{1} {4}
−
\frac1 3 \frac{1} {3}
of the radius of the galaxies, fully consistent with values derived for the Milky Way, the LMC, and M 33. Therefore, not only the radio SNRs, but also the X-ray detected SNR sample can be interpreted to be representative for the CR sources within a galaxy.
Astrophysics and Space Science 01/2004; 289(3):283-286. · 1.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Based on XMM-Newton EPIC data of four pointings towards the Small Magellanic Cloud (SMC), results on timing and spectral analyses of 16 known high mass X-ray binaries (HMXBs) and HMXB candidates in the SMC are presented. We confirm the pulse periods of four sources which were known to show pulsations. In addition, two new X-ray pulsars are discovered: XMMU J005605.2-722200 with P_pulse = 140.1 +/- 0.3 s and RX J0057.8-7207 with P_pulse = 152.34 +/- 0.05 s. Due to the low Galactic foreground absorption, X-ray binary systems in the Magellanic Clouds are well suited for studies of the soft component in their X-ray spectrum. Spectral analysis reveals soft emission besides a power law component in the spectra of three sources. The existence of emission lines in at least one of them corroborates the thermal nature of this emission with temperatures of 0.2 - 0.3 keV and heavy element abundances lower than solar. For the HMXB SMC X-2 which was in a low luminosity state, we determine a flux upper limit of 1.5 x 10^-14 erg cm^-2 s^-1 (0.3 - 10.0 keV). Furthermore, two new sources (XMMU J005735.7-721932 and XMMU J010030.2-722035) with hard spectrum and emission line objects as likely optical counterparts are proposed as new X-ray binary candidates. Comment: 17 pages, 16 figures, accepted by A&A
03/2003;
-
[show abstract]
[hide abstract]
ABSTRACT: All 543 pointed observations of the ROSAT High Resolution Imager (HRI) with exposure times higher than 50 sec in a field of 10 deg x 10 deg covering the Large Magellanic Cloud (LMC) were analyzed. A catalogue was produced containing 397 X-ray sources with their properties measured by the HRI. The list was cross-correlated with the ROSAT Position Sensitive Propotional Counter (PSPC) source catalogue presented by Haberl & Pietsch (1999), the SIMBAD data base, and the TYCHO catalogue. 138 HRI sources are contained in the PSPC catalogue. The spatial resolution of the HRI was higher than that of the PSPC and the source position could be determined with errors mostly smaller than 15 arcsec which are dominated by systematic attitude errors. 94 HRI sources were identified with known objects based on their positional coincidence and X-ray properties. The catalogue contains 39 foreground stars, 24 supernova remnants (SNRs), five supersoft sources (SSSs), nine X-ray binaries (XBs), and nine AGN well known from literature. Another eight sources were identified with known candidates for these source classes. Additional 21 HRI sources are suggested in the present work as candidates for SNR, X-ray binary in the LMC, or background AGN because of their extent, hardness ratios, X-ray to optical flux ratio, or flux variability. Comment: 22 pages, 8 figures, 4 tables
02/2000;
-
Kajita, T.;Asaoka. Y.;Matsubara, Y.;Sasaki, M.: 28th International Cosmic Ray Conference - ICRC 2003 -, Universal Academy Press, 2639-2642 (2003).
