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Papers by Luke Bozzetto
Monthly Notices of the Royal Astronomical Society, 2022
We report the discovery of J0624–6948, a low-surface brightness radio ring, lying between the Gal... more We report the discovery of J0624–6948, a low-surface brightness radio ring, lying between the Galactic Plane and the large magellanic cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ∼196 arcsec. This source has phenomenological similarities to odd radio circles (ORCs). Significant differences to the known ORCs – a flatter radio spectral index, the lack of a prominent central galaxy as a possible host, and larger apparent size – suggest that J0624–6948 may be a different type of object. We argue that the most plausible explanation for J0624–6948 is an intergalactic supernova remnant due to a star that resided in the LMC outskirts that had undergone a single-degenerate type Ia supernova, and we are seeing its remnant expand into a rarefied, intergalactic environment. We also examine if a massive star or a white dwarf binary ejected from either galaxy could be the supernova progenitor. Finally, we consi...
Astronomy & Astrophysics, 2016
Aims. We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in th... more Aims. We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). Using primarily XMM-Newton observations, we conduct a systematic spectral analysis of LMC SNRs to gain new insight into their evolution and the interplay with their host galaxy. Methods. We combined all the archival XMM-Newton observations of the LMC with those of our Very Large Programme LMC survey. We produced X-ray images and spectra of 51 SNRs, out of a list of 59 objects compiled from the literature and augmented with newly found objects. Using a careful modelling of the background, we consistently analysed all the X-ray spectra and measure temperatures, luminosities, and chemical compositions. The locations of SNRs are compared to the distributions of stars, cold gas, and warm gas in the LMC, and we investigated the connection between the SNRs and their local environment, characterised by various star formation histories. We tentatively typed all LMC SNRs, in order to constrain the ratio of core-collapse to type Ia SN rates in the LMC. We also compared the column densities derived from X-ray spectra to H i maps, thus probing the three-dimensional structure of the LMC. Results. This work provides the first homogeneous catalogue of the X-ray spectral properties of SNRs in the LMC. It offers a complete census of LMC remnants whose X-ray emission exhibits Fe K lines (13% of the sample), or reveals the contribution from hot supernova ejecta (39%), which both give clues to the progenitor types. The abundances of O, Ne, Mg, Si, and Fe in the hot phase of the LMC interstellar medium are found to be between 0.2 and 0.5 times the solar values with a lower abundance ratio [α/Fe] than in the Milky Way. The current ratio of core-collapse to type Ia SN rates in the LMC is constrained to N CC /N Ia = 1.35(+0.11 −0.24), which is lower than in local SN surveys and galaxy clusters. Our comparison of the X-ray luminosity functions of SNRs in Local Group galaxies (LMC, SMC, M31, and M33) reveals an intriguing excess of bright objects in the LMC. Finally, 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.
Astronomy & Astrophysics, 2015
Aims. We present a multi-frequency study of the supernova remnant MCSNR J0512−6707 in the Large M... more Aims. We present a multi-frequency study of the supernova remnant MCSNR J0512−6707 in the Large Magellanic Cloud. Methods. We used new data from XMM-Newton to characterise the X-ray emission and data from the Australian Telescope Compact Array, the Magellanic Cloud Emission Line Survey, and Spitzer to gain a picture of the environment into which the remnant is expanding. We performed a morphological study, determined radio polarisation and magnetic field orientation, and performed an X-ray spectral analysis. Results. We estimated the remnant's size to be 24.9 (±1.5) × 21.9 (±1.5) pc, with the major axis rotated ∼29 • east of north. Radio polarisation images at 3 cm and 6 cm indicate a higher degree of polarisation in the northwest and southeast tangentially oriented to the SNR shock front, indicative of an SNR compressing the magnetic field threading the interstellar medium. The X-ray spectrum is unusual as it requires a soft (∼0.2 keV) collisional ionisation equilibrium thermal plasma of interstellar medium abundance, in addition to a harder component. Using our fit results and the Sedov dynamical model, we showed that the thermal emission is not consistent with a Sedov remnant. We suggested that the thermal X-rays can be explained by MCSNR J0512−6707 having initially evolved into a wind-blown cavity and is now interacting with the surrounding dense shell. The origin of the hard component remains unclear. We could not determine the supernova type from the X-ray spectrum. Indirect evidence for the type is found in the study of the local stellar population and star formation history in the literature, which suggests a core-collapse origin. Conclusions. MCSNR J0512−6707 likely resulted from the core-collapse of high mass progenitor which carved a low density cavity into its surrounding medium, with the soft X-rays resulting from the impact of the blast wave with the surrounding shell. The unusual hard X-ray component requires deeper and higher spatial resolution radio and X-ray observations to confirm its origin.
Astronomy & Astrophysics, 2012
Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be inve... more Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be investigated in detail with radio, optical, and X-ray observations. SNR J0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies. Aims. We study the emission of SNR J0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant. Methods. We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNR J0453-6829. We studied the morphology of SNR J0453-6829 from radio, optical, and X-ray images and investigated the energy spectra in the different parts of the remnant. Results. Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index α Core of −0.04 ± 0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with α Shell = −0.43 ± 0.01. We detect regions with a mean polarisation of P (12 ± 4)% at 6 cm and (9 ± 2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31 ± 1) pc × (29 ± 1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12 000-15 000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56 cm −3 , typical for LMC remnants, a large swept-up mass of 830 M , and an explosion energy of 7.6 × 10 50 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material.
Astronomy & Astrophysics, 2014
Aims. We present a detailed multi-wavelength study of four new supernova remnants (SNRs) in the L... more Aims. We present a detailed multi-wavelength study of four new supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). The objects were identified as SNR candidates in X-ray observations performed during the survey of the LMC with XMM-Newton. Methods. Data obained with XMM-Newton are used to investigate the morphological and spectral features of the remnants in X-rays. We measure the plasma conditions, look for supernova (SN) ejecta emission, and constrain some of the SNR properties (e.g. age and ambient density). We supplement the X-ray data with optical, infrared, and radio-continuum archival observations, which allow us to understand the conditions resulting in the current appearance of the remnants. Based on the spatially-resolved star formation history (SFH) of the LMC together with the X-ray spectra, we attempt to type the supernovae that created the remnants. Results. We confirm all four objects as SNRs, to which we assign the names MCSNR J0508−6830, MCSNR J0511−6759, MCSNR J0514−6840, and MCSNR J0517−6759. In the first two remnants, an X-ray bright plasma is surrounded by very faint [S ii] emission. The emission from the central plasma is dominated by Fe L-shell lines, and the derived iron abundance is greatly in excess of solar. This establishes their type Ia (i.e. thermonuclear) SN origin. They appear to be more evolved versions of other Magellanic Cloud iron-rich SNRs which are centrally-peaked in X-rays. From the two other remnants (MCSNR J0514−6840 and MCSNR J0517−6759), we do not see ejecta emission. At all wavelengths at which they are detected, the local environment plays a key role in their observational appearance. We present evidence that MCSNR J0517−6759 is close to and interacting with a molecular cloud, suggesting a massive progenitor.
Astrophysics and Space Science, 2019
Alsaberi R. Z. E.
Supernova remnants (SNRs) mark the end point of stellar evolution. They return nucleosynthesis pr... more Supernova remnants (SNRs) mark the end point of stellar evolution. They return nucleosynthesis products to the interstellar medium (ISM), enriching and mixing it with freshly-produced heavy elements. Studying SNRs in general, and their X-ray emission in particular, is crucial to advance our understanding of many important astrophysical processes. With an XMM-Newton Very Large Programme (PI: F. Haberl), we conducted an X-ray survey of the Large Magellanic Cloud (LMC). As opposed to the Milky Way, the LMC offers an ideal target, at a well-constrained distance with small absorption column densities. Thus, X-ray properties of the evolved end of the SNR population of a galaxy can be studied. I will present the characteristics of the newly X-ray-discovered SNRs, with emphasis on the discovery of several iron-rich SNRs, which are the most evolved remnants of type Ia (i.e. thermonuclear) supernovae. I will take advantage of the high level of completeness of our sample of SNRs to i) present the X-ray luminosity function (XLF) of LMC SNRs, extended towards lowerluminosity objects, comparing it to the XLF of SNRs in other galaxies; and ii) compare the spatial distribution of SNRs and star formation histories in the LMC
Monthly Notices of the Royal Astronomical Society
We present a new Australian Square Kilometre Array Pathfinder (ASKAP) sample of 14 radio supernov... more We present a new Australian Square Kilometre Array Pathfinder (ASKAP) sample of 14 radio supernova remnants (SNR) candidates in the Large Magellanic Cloud (LMC). This new sample is a significant increase to the known number of older, larger, and low surface brightness LMC SNRs. We employ a multifrequency search for each object and found possible traces of optical and occasionally X-ray emission in several of these 14 SNR candidates. One of these 14 SNR candidates (MCSNR J0522 – 6543) has multifrequency properties that strongly indicate a bona fide SNR. We also investigate a sample of 20 previously suggested LMC SNR candidates and confirm the SNR nature of MCSNR J0506 – 6815. We detect lower surface brightness SNR candidates which were likely formed by a combination of shock waves and strong stellar winds from massive progenitors (and possibly surrounding OB stars). Some of our new SNR candidates are also found in lower density environments in which SNe type Ia explode inside a previ...
Monthly Notices of the Royal Astronomical Society, 2019
We present two new radio continuum images from the Australian Square Kilometre Array Pathfinder (... more We present two new radio continuum images from the Australian Square Kilometre Array Pathfinder (ASKAP) survey in the direction of the Small Magellanic Cloud (SMC). These images are part of the Evolutionary Map of the Universe (EMU) Early Science Project (ESP) survey of the Small and Large Magellanic Clouds. The two new source lists produced from these images contain radio continuum sources observed at 960 MHz (4489 sources) and 1320 MHz (5954 sources) with a bandwidth of 192 MHz and beam sizes of 30.0 × 30.0 arcsec2 and 16.3 × 15.1 arcsec2, respectively. The median root mean square (RMS) noise values are 186 mu\mumuJy beam−1 (960 MHz) and 165 mu\mumuJy beam−1 (1320 MHz). To create point source catalogues, we use these two source lists, together with the previously published Molonglo Observatory Synthesis Telescope (MOST) and the Australia Telescope Compact Array (ATCA) point source catalogues to estimate spectral indices for the whole population of radio point sources found in the surv...
Monthly Notices of the Royal Astronomical Society, 2019
We report the discovery of a new Small Magellanic Cloud Pulsar Wind Nebula (PWN) at the edge of t... more We report the discovery of a new Small Magellanic Cloud Pulsar Wind Nebula (PWN) at the edge of the Supernova Remnant (SNR) DEM S5. The pulsar powered object has a cometary morphology similar to the Galactic PWN analogs PSR B1951+32 and 'the mouse'. It is travelling supersonically through the interstellar medium. We estimate the Pulsar kick velocity to be in the range of 700-2000 km s −1 for an age between 28-10 kyr. The radio spectral index for this SNR-PWN-pulsar system is flat (-0.29 ± 0.01) consistent with other similar objects. We infer that the putative pulsar has a radio spectral index of-1.8, which is typical for Galactic pulsars. We searched for dispersion measures (DMs) up to 1000 cm −3 pc but found no convincing candidates with a S/N greater than 8. We produce a polarisation map for this PWN at 5500 MHz and find a mean fractional polarisation of P ∼23 percent. The X-ray power-law spectrum (Γ ∼2) is indicative of non-thermal synchrotron emission as is expected from PWN-pulsar system. Finally, we detect DEM S5 in Infrared (IR) bands. Our IR photometric measurements strongly indicate the presence of shocked gas which is expected for SNRs. However, it is unusual to detect such IR emission in a SNR with a supersonic bow-shock PWN. We also find a low-velocity H i cloud of ∼107 km s −1 which is possibly interacting with DEM S5. SNR DEM S5 is the first confirmed detection of a pulsar-powered bow shock nebula found outside the Galaxy.
RESUMEN Este documento (rm-journal-example.tex-última actualización 9 de septiembre del 2007) pro... more RESUMEN Este documento (rm-journal-example.tex-última actualización 9 de septiembre del 2007) proporciona un tutorial breve en el uso de la versión 3 de los macros de L A T E X rmaa y además puede servir cómo modelo para la preparación de los artículos que se publicarán en la revista principal. Se puede encontrar más detalles en la guía del usuario (authorguide.pdf). Se supone que usted es ya familiar con los rudimentos del L A T E X. En el caso contrario, se dan algunas referencias convenientes en el authorguide.pdf.
Serbian Astronomical Journal, 2012
We report on new Australian Telescope Compact Array (ATCA) observations of SNR J0519-6902. The Su... more We report on new Australian Telescope Compact Array (ATCA) observations of SNR J0519-6902. The Supernova Remnant (SNR) is small in size (~8 pc) and exhibits a typical SNR spectrum with ? = -0.53?0.07, with steeper spectral indices towards the northern limb of the remnant. SNR J0519-6902 contains a low level of radially orientated polarisation at wavelengths of 3 and 6 cm, which is typical of younger SNRs. A fairly strong magnetic field was estimated to ~171?G. The remnant appears to be the result of a typical Type Ia supernova, sharing many properties with another small and young Type Ia LMC SNR, J0509-6731.
Astronomy & Astrophysics, 2014
Aims. We present a detailed study of the superbubble 30 Dor C and the newly identified supernova ... more Aims. We present a detailed study of the superbubble 30 Dor C and the newly identified supernova remnant MCSNR J0536-6913 in the Large Magellanic Cloud. Methods. All available XMM-Newton data (flare-filtered exposure times of 420 ks EPIC-pn, 556 ks EPIC-MOS1, 614 ks EPIC-MOS2) were used to characterise the thermal X-ray emission in the region. An analysis of the non-thermal X-ray emission is also presented and discussed in the context of emission mechanisms previously suggested in the literature. These data are supplemented by X-ray data from Chandra, optical data from the Magellanic Cloud Emission Line Survey, and radio data from the Australia Telescope Compact Array and the Molonglo Observatory Synthesis Telescope. Results. The brightest thermal emission towards 30 Dor C was found to be associated with a new supernova remnant, MCSNR J0536−6913. X-ray spectral analysis of MCSNR J0536−6913 suggested an ejecta-dominated remnant with lines of O, Ne, Mg, and Si, and a total 0.3−10 keV X-ray luminosity of ∼8 × 10 34 erg s −1. Based on derived ejecta abundance ratios, we determined the mass of the stellar progenitor to be either ∼18 M or as high as > ∼ 40 M , though the spectral fits were subject to simplifying assumptions (e.g., uniform temperature and well-mixed ejecta). The thermal emission from the superbubble exhibited enrichment by α-process elements, evidence for a recent core-collapse SNR interaction with the superbubble shell. We detected non-thermal X-ray emission throughout 30 Dor C, with the brightest regions being highly correlated with the Hα and radio shells. We created a non-thermal spectral energy distribution for the northeastern shell of 30 Dor C which was best-fit with an exponentially cutoff synchrotron model. Conclusions. Thermal X-ray emission from 30 Dor C is very complex, consisting of a large scale superbubble emission at the eastern shell wall with the brightest emission due to MCSNR J0536−6913. The fact that the non-thermal spectral energy distribution of the superbubble shell was observed to roll-off is further evidence that the non-thermal X-ray emission from 30 Dor C is synchrotron in origin.
Monthly Notices of the Royal Astronomical Society, 2022
We report the discovery of J0624–6948, a low-surface brightness radio ring, lying between the Gal... more We report the discovery of J0624–6948, a low-surface brightness radio ring, lying between the Galactic Plane and the large magellanic cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ∼196 arcsec. This source has phenomenological similarities to odd radio circles (ORCs). Significant differences to the known ORCs – a flatter radio spectral index, the lack of a prominent central galaxy as a possible host, and larger apparent size – suggest that J0624–6948 may be a different type of object. We argue that the most plausible explanation for J0624–6948 is an intergalactic supernova remnant due to a star that resided in the LMC outskirts that had undergone a single-degenerate type Ia supernova, and we are seeing its remnant expand into a rarefied, intergalactic environment. We also examine if a massive star or a white dwarf binary ejected from either galaxy could be the supernova progenitor. Finally, we consi...
Astronomy & Astrophysics, 2016
Aims. We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in th... more Aims. We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). Using primarily XMM-Newton observations, we conduct a systematic spectral analysis of LMC SNRs to gain new insight into their evolution and the interplay with their host galaxy. Methods. We combined all the archival XMM-Newton observations of the LMC with those of our Very Large Programme LMC survey. We produced X-ray images and spectra of 51 SNRs, out of a list of 59 objects compiled from the literature and augmented with newly found objects. Using a careful modelling of the background, we consistently analysed all the X-ray spectra and measure temperatures, luminosities, and chemical compositions. The locations of SNRs are compared to the distributions of stars, cold gas, and warm gas in the LMC, and we investigated the connection between the SNRs and their local environment, characterised by various star formation histories. We tentatively typed all LMC SNRs, in order to constrain the ratio of core-collapse to type Ia SN rates in the LMC. We also compared the column densities derived from X-ray spectra to H i maps, thus probing the three-dimensional structure of the LMC. Results. This work provides the first homogeneous catalogue of the X-ray spectral properties of SNRs in the LMC. It offers a complete census of LMC remnants whose X-ray emission exhibits Fe K lines (13% of the sample), or reveals the contribution from hot supernova ejecta (39%), which both give clues to the progenitor types. The abundances of O, Ne, Mg, Si, and Fe in the hot phase of the LMC interstellar medium are found to be between 0.2 and 0.5 times the solar values with a lower abundance ratio [α/Fe] than in the Milky Way. The current ratio of core-collapse to type Ia SN rates in the LMC is constrained to N CC /N Ia = 1.35(+0.11 −0.24), which is lower than in local SN surveys and galaxy clusters. Our comparison of the X-ray luminosity functions of SNRs in Local Group galaxies (LMC, SMC, M31, and M33) reveals an intriguing excess of bright objects in the LMC. Finally, 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.
Astronomy & Astrophysics, 2015
Aims. We present a multi-frequency study of the supernova remnant MCSNR J0512−6707 in the Large M... more Aims. We present a multi-frequency study of the supernova remnant MCSNR J0512−6707 in the Large Magellanic Cloud. Methods. We used new data from XMM-Newton to characterise the X-ray emission and data from the Australian Telescope Compact Array, the Magellanic Cloud Emission Line Survey, and Spitzer to gain a picture of the environment into which the remnant is expanding. We performed a morphological study, determined radio polarisation and magnetic field orientation, and performed an X-ray spectral analysis. Results. We estimated the remnant's size to be 24.9 (±1.5) × 21.9 (±1.5) pc, with the major axis rotated ∼29 • east of north. Radio polarisation images at 3 cm and 6 cm indicate a higher degree of polarisation in the northwest and southeast tangentially oriented to the SNR shock front, indicative of an SNR compressing the magnetic field threading the interstellar medium. The X-ray spectrum is unusual as it requires a soft (∼0.2 keV) collisional ionisation equilibrium thermal plasma of interstellar medium abundance, in addition to a harder component. Using our fit results and the Sedov dynamical model, we showed that the thermal emission is not consistent with a Sedov remnant. We suggested that the thermal X-rays can be explained by MCSNR J0512−6707 having initially evolved into a wind-blown cavity and is now interacting with the surrounding dense shell. The origin of the hard component remains unclear. We could not determine the supernova type from the X-ray spectrum. Indirect evidence for the type is found in the study of the local stellar population and star formation history in the literature, which suggests a core-collapse origin. Conclusions. MCSNR J0512−6707 likely resulted from the core-collapse of high mass progenitor which carved a low density cavity into its surrounding medium, with the soft X-rays resulting from the impact of the blast wave with the surrounding shell. The unusual hard X-ray component requires deeper and higher spatial resolution radio and X-ray observations to confirm its origin.
Astronomy & Astrophysics, 2012
Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be inve... more Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be investigated in detail with radio, optical, and X-ray observations. SNR J0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies. Aims. We study the emission of SNR J0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant. Methods. We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNR J0453-6829. We studied the morphology of SNR J0453-6829 from radio, optical, and X-ray images and investigated the energy spectra in the different parts of the remnant. Results. Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index α Core of −0.04 ± 0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with α Shell = −0.43 ± 0.01. We detect regions with a mean polarisation of P (12 ± 4)% at 6 cm and (9 ± 2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31 ± 1) pc × (29 ± 1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12 000-15 000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56 cm −3 , typical for LMC remnants, a large swept-up mass of 830 M , and an explosion energy of 7.6 × 10 50 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material.
Astronomy & Astrophysics, 2014
Aims. We present a detailed multi-wavelength study of four new supernova remnants (SNRs) in the L... more Aims. We present a detailed multi-wavelength study of four new supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). The objects were identified as SNR candidates in X-ray observations performed during the survey of the LMC with XMM-Newton. Methods. Data obained with XMM-Newton are used to investigate the morphological and spectral features of the remnants in X-rays. We measure the plasma conditions, look for supernova (SN) ejecta emission, and constrain some of the SNR properties (e.g. age and ambient density). We supplement the X-ray data with optical, infrared, and radio-continuum archival observations, which allow us to understand the conditions resulting in the current appearance of the remnants. Based on the spatially-resolved star formation history (SFH) of the LMC together with the X-ray spectra, we attempt to type the supernovae that created the remnants. Results. We confirm all four objects as SNRs, to which we assign the names MCSNR J0508−6830, MCSNR J0511−6759, MCSNR J0514−6840, and MCSNR J0517−6759. In the first two remnants, an X-ray bright plasma is surrounded by very faint [S ii] emission. The emission from the central plasma is dominated by Fe L-shell lines, and the derived iron abundance is greatly in excess of solar. This establishes their type Ia (i.e. thermonuclear) SN origin. They appear to be more evolved versions of other Magellanic Cloud iron-rich SNRs which are centrally-peaked in X-rays. From the two other remnants (MCSNR J0514−6840 and MCSNR J0517−6759), we do not see ejecta emission. At all wavelengths at which they are detected, the local environment plays a key role in their observational appearance. We present evidence that MCSNR J0517−6759 is close to and interacting with a molecular cloud, suggesting a massive progenitor.
Astrophysics and Space Science, 2019
Alsaberi R. Z. E.
Supernova remnants (SNRs) mark the end point of stellar evolution. They return nucleosynthesis pr... more Supernova remnants (SNRs) mark the end point of stellar evolution. They return nucleosynthesis products to the interstellar medium (ISM), enriching and mixing it with freshly-produced heavy elements. Studying SNRs in general, and their X-ray emission in particular, is crucial to advance our understanding of many important astrophysical processes. With an XMM-Newton Very Large Programme (PI: F. Haberl), we conducted an X-ray survey of the Large Magellanic Cloud (LMC). As opposed to the Milky Way, the LMC offers an ideal target, at a well-constrained distance with small absorption column densities. Thus, X-ray properties of the evolved end of the SNR population of a galaxy can be studied. I will present the characteristics of the newly X-ray-discovered SNRs, with emphasis on the discovery of several iron-rich SNRs, which are the most evolved remnants of type Ia (i.e. thermonuclear) supernovae. I will take advantage of the high level of completeness of our sample of SNRs to i) present the X-ray luminosity function (XLF) of LMC SNRs, extended towards lowerluminosity objects, comparing it to the XLF of SNRs in other galaxies; and ii) compare the spatial distribution of SNRs and star formation histories in the LMC
Monthly Notices of the Royal Astronomical Society
We present a new Australian Square Kilometre Array Pathfinder (ASKAP) sample of 14 radio supernov... more We present a new Australian Square Kilometre Array Pathfinder (ASKAP) sample of 14 radio supernova remnants (SNR) candidates in the Large Magellanic Cloud (LMC). This new sample is a significant increase to the known number of older, larger, and low surface brightness LMC SNRs. We employ a multifrequency search for each object and found possible traces of optical and occasionally X-ray emission in several of these 14 SNR candidates. One of these 14 SNR candidates (MCSNR J0522 – 6543) has multifrequency properties that strongly indicate a bona fide SNR. We also investigate a sample of 20 previously suggested LMC SNR candidates and confirm the SNR nature of MCSNR J0506 – 6815. We detect lower surface brightness SNR candidates which were likely formed by a combination of shock waves and strong stellar winds from massive progenitors (and possibly surrounding OB stars). Some of our new SNR candidates are also found in lower density environments in which SNe type Ia explode inside a previ...
Monthly Notices of the Royal Astronomical Society, 2019
We present two new radio continuum images from the Australian Square Kilometre Array Pathfinder (... more We present two new radio continuum images from the Australian Square Kilometre Array Pathfinder (ASKAP) survey in the direction of the Small Magellanic Cloud (SMC). These images are part of the Evolutionary Map of the Universe (EMU) Early Science Project (ESP) survey of the Small and Large Magellanic Clouds. The two new source lists produced from these images contain radio continuum sources observed at 960 MHz (4489 sources) and 1320 MHz (5954 sources) with a bandwidth of 192 MHz and beam sizes of 30.0 × 30.0 arcsec2 and 16.3 × 15.1 arcsec2, respectively. The median root mean square (RMS) noise values are 186 mu\mumuJy beam−1 (960 MHz) and 165 mu\mumuJy beam−1 (1320 MHz). To create point source catalogues, we use these two source lists, together with the previously published Molonglo Observatory Synthesis Telescope (MOST) and the Australia Telescope Compact Array (ATCA) point source catalogues to estimate spectral indices for the whole population of radio point sources found in the surv...
Monthly Notices of the Royal Astronomical Society, 2019
We report the discovery of a new Small Magellanic Cloud Pulsar Wind Nebula (PWN) at the edge of t... more We report the discovery of a new Small Magellanic Cloud Pulsar Wind Nebula (PWN) at the edge of the Supernova Remnant (SNR) DEM S5. The pulsar powered object has a cometary morphology similar to the Galactic PWN analogs PSR B1951+32 and 'the mouse'. It is travelling supersonically through the interstellar medium. We estimate the Pulsar kick velocity to be in the range of 700-2000 km s −1 for an age between 28-10 kyr. The radio spectral index for this SNR-PWN-pulsar system is flat (-0.29 ± 0.01) consistent with other similar objects. We infer that the putative pulsar has a radio spectral index of-1.8, which is typical for Galactic pulsars. We searched for dispersion measures (DMs) up to 1000 cm −3 pc but found no convincing candidates with a S/N greater than 8. We produce a polarisation map for this PWN at 5500 MHz and find a mean fractional polarisation of P ∼23 percent. The X-ray power-law spectrum (Γ ∼2) is indicative of non-thermal synchrotron emission as is expected from PWN-pulsar system. Finally, we detect DEM S5 in Infrared (IR) bands. Our IR photometric measurements strongly indicate the presence of shocked gas which is expected for SNRs. However, it is unusual to detect such IR emission in a SNR with a supersonic bow-shock PWN. We also find a low-velocity H i cloud of ∼107 km s −1 which is possibly interacting with DEM S5. SNR DEM S5 is the first confirmed detection of a pulsar-powered bow shock nebula found outside the Galaxy.
RESUMEN Este documento (rm-journal-example.tex-última actualización 9 de septiembre del 2007) pro... more RESUMEN Este documento (rm-journal-example.tex-última actualización 9 de septiembre del 2007) proporciona un tutorial breve en el uso de la versión 3 de los macros de L A T E X rmaa y además puede servir cómo modelo para la preparación de los artículos que se publicarán en la revista principal. Se puede encontrar más detalles en la guía del usuario (authorguide.pdf). Se supone que usted es ya familiar con los rudimentos del L A T E X. En el caso contrario, se dan algunas referencias convenientes en el authorguide.pdf.
Serbian Astronomical Journal, 2012
We report on new Australian Telescope Compact Array (ATCA) observations of SNR J0519-6902. The Su... more We report on new Australian Telescope Compact Array (ATCA) observations of SNR J0519-6902. The Supernova Remnant (SNR) is small in size (~8 pc) and exhibits a typical SNR spectrum with ? = -0.53?0.07, with steeper spectral indices towards the northern limb of the remnant. SNR J0519-6902 contains a low level of radially orientated polarisation at wavelengths of 3 and 6 cm, which is typical of younger SNRs. A fairly strong magnetic field was estimated to ~171?G. The remnant appears to be the result of a typical Type Ia supernova, sharing many properties with another small and young Type Ia LMC SNR, J0509-6731.
Astronomy & Astrophysics, 2014
Aims. We present a detailed study of the superbubble 30 Dor C and the newly identified supernova ... more Aims. We present a detailed study of the superbubble 30 Dor C and the newly identified supernova remnant MCSNR J0536-6913 in the Large Magellanic Cloud. Methods. All available XMM-Newton data (flare-filtered exposure times of 420 ks EPIC-pn, 556 ks EPIC-MOS1, 614 ks EPIC-MOS2) were used to characterise the thermal X-ray emission in the region. An analysis of the non-thermal X-ray emission is also presented and discussed in the context of emission mechanisms previously suggested in the literature. These data are supplemented by X-ray data from Chandra, optical data from the Magellanic Cloud Emission Line Survey, and radio data from the Australia Telescope Compact Array and the Molonglo Observatory Synthesis Telescope. Results. The brightest thermal emission towards 30 Dor C was found to be associated with a new supernova remnant, MCSNR J0536−6913. X-ray spectral analysis of MCSNR J0536−6913 suggested an ejecta-dominated remnant with lines of O, Ne, Mg, and Si, and a total 0.3−10 keV X-ray luminosity of ∼8 × 10 34 erg s −1. Based on derived ejecta abundance ratios, we determined the mass of the stellar progenitor to be either ∼18 M or as high as > ∼ 40 M , though the spectral fits were subject to simplifying assumptions (e.g., uniform temperature and well-mixed ejecta). The thermal emission from the superbubble exhibited enrichment by α-process elements, evidence for a recent core-collapse SNR interaction with the superbubble shell. We detected non-thermal X-ray emission throughout 30 Dor C, with the brightest regions being highly correlated with the Hα and radio shells. We created a non-thermal spectral energy distribution for the northeastern shell of 30 Dor C which was best-fit with an exponentially cutoff synchrotron model. Conclusions. Thermal X-ray emission from 30 Dor C is very complex, consisting of a large scale superbubble emission at the eastern shell wall with the brightest emission due to MCSNR J0536−6913. The fact that the non-thermal spectral energy distribution of the superbubble shell was observed to roll-off is further evidence that the non-thermal X-ray emission from 30 Dor C is synchrotron in origin.