arXiv subjects

E. M. Reynoso

Publications and source records attributed to E. M. Reynoso.

At least 19 recordsLinked to original sources

arXiv2026

Molecular and Atomic Gas Associated with the Gamma Ray Supernova Remnant RCW 103

We present a study of the interstellar molecular and atomic gas associated with the gamma-ray supernova remnant (SNR) RCW 103 using the Mopra $^{12}$CO($J$ = 1-0), Atacama Large Millimeter/submillimeter Array $^{13}$CO($J$ = 1-0), and the Australia Telescope Compact Array & Parkes HI data. We find that CO clouds in the velocity range from $-58.7$ to $-43.5$ km s$^{-1}$ show a clear spatial correspondence with the X-ray shell of RCW 103, particularly extending from the northwestern to the southeastern regions. The position-velocity diagram of the CO emission reveals an expanding gas motion with an expansion velocity of $ΔV \sim$$7.5$ km s$^{-1}$, which may have been produced by shock waves and/or stellar winds from the progenitor system. We estimate the total cosmic-ray proton energy to be $\sim$$3.0^{+1.1}_{-0.6} \times 10^{47}$ erg, adopting a total interstellar proton density of $\sim$$810$ cm$^{-3}$. This value is more than an order of magnitude lower than those inferred for other gamma-ray emitting SNRs of comparable age. Given that a substantial amount of dense gas remains within the interior of RCW 103, where thermal X-ray emission is dominant, our results possibly suggest that a significant fraction of the shock energy may have been converted into thermal energy via gas heating, thereby reducing the efficiency of cosmic-ray acceleration.

astro-ph.HE↗

arXiv2023

The sculpting of rectangular and jet-like morphologies in supernova remnants by anisotropic equatorially-confined progenitor stellar winds

Thermonuclear and core-collapse supernova remnants (SNRs) are the nebular leftovers of defunct stars. Their morphology and emission properties provide insights into the evolutionary history of the progenitor star. But while some SNRs are spherical, as expected from a point-like explosion expanding into a roughly uniform medium, many others exhibit complex non-spherical morphologies which are often not easily explained. In this work, we use three-dimensional magnetohydrodynamic simulations to show that rectangular and jet-like morphologies can be explained by supernovae (SNe), either type Ia or type II, expanding within anisotropic, bipolar stellar wind bubbles driven by the progenitor star. The stellar wind has an anisotropic density distribution, which channels the SN ejecta differently depending on the anisotropy characteristics. We compute synthetic thermal (X-ray) and non-thermal (synchrotron) emission maps from our numerical simulations to compare with observations. We find rectangular morphologies are generated when the stellar wind has a high mass loss rate and forms a dense, narrow disk at the equatorial region. Instead, a jet-like or ear-like morphology is obtained when the stellar wind develops a wide, dense disk. Stellar winds with low mass-loss rates do not strongly influence the SNR morphology. Finally, our synthetic synchrotron and X-ray maps for the high mass-loss rate case qualitatively agree with the observations of the SNRs G332.5-5.6 and G290.1-0.8.

astro-ph.HE↗

arXiv2022

Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Puppis A

We have carried out a study of the interstellar medium (ISM) toward a shell-like supernova remnant SNR Puppis A by using the NANTEN CO and ATCA HI data. We synthesized a comprehensive picture of the SNR radiation by combining the ISM data with the gamma-ray and X-ray distributions. The ISM, both atomic and molecular gas, is dense and highly clumpy, and is distributed all around the SNR, but mainly in the north-east. The CO distribution revealed an enhanced line intensity ratio of CO($J$ = 2-1)/($J$ = 1-0) transitions as well as CO line broadening, which indicate shock heating/acceleration. The results support that Puppis A is located at 1.4 kpc, in the local arm. The ISM interacting with the SNR has a large mass of $\sim$10$^{4}$ $M_{\odot}$ which is dominated by HI, showing good spatial correspondence with the Fermi-LAT gamma-ray image. This favors the hadronic origin of the gamma-rays, while additional contribution of the leptonic component is not excluded. The distribution of the X-ray ionization timescales within the shell suggests that the shock front ionized various parts of the ISM at epochs ranging over a few to ten 1000 yr. We therefore suggest that the age of the SNR is around 10$^{4}$ yr as given by the largest ionization timescale. We estimate the total cosmic ray energy $W_{\rm p}$ to be 10$^{47}$ erg, which is well placed in the cosmic-ray escaping phase of an age-$W_{\rm p}$ plot including more than ten SNRs.

astro-ph.HE↗

arXiv2022

Rectangular core-collapse supernova remnants: application to Puppis A

Core-collapse supernova remnants are the gaseous nebulae of galactic interstellar media (ISM) formed after the explosive death of massive stars. Their morphology and emission properties depend both on the surrounding circumstellar structure shaped by the stellar wind-ISM interaction of the progenitor star and on the local conditions of the ambient medium. In the warm phase of the Galactic plane (n = 1/cm3, T = 8000 K), an organised magnetic field of strength 7 microG has profound consequences on the morphology of the wind bubble of massive stars at rest. In this paper we show through 2.5D magneto-hydrodynamical simulations, in the context of a Wolf-Rayet-evolving 35 Mo star, that it affects the development of its supernova remnant. When the supernova remnant reaches its middle age (15 to 20 kyr), it adopts a tubular shape that results from the interaction between the isotropic supernova ejecta and the anisotropic, magnetised, shocked stellar progenitor bubble into which the supernova blast wave expands. Our calculations for non-thermal emission, i.e. radio synchrotron and inverse Compton radiation, reveal that such supernova remnants can, due to projection effects, appear as rectangular objects in certain cases. This mechanism for shaping a supernova remnant is similar to the bipolar and elliptical planetary nebula production by wind-wind interaction in the low-mass regime of stellar evolution. If such a rectangular core-collapse supernova remnant is created, the progenitor star must not have been a runaway star. We propose that such a mechanism is at work in the shaping of the asymmetric core-collapse supernova remnant Puppis A.

astro-ph.HE↗

arXiv2020

Physical characterization of S169: A prototypical IR bubble associated with the massive star-forming region IRAS12326-6245

With the aim of studying the properties of Galactic IR bubbles and their impact in massive star formation, we present a study of the IR bubble S169, associated with the massive star forming region IRAS12326-6245. We used CO(2-1),$^{13}$CO(2-1), C$^{18}$O(2-1), HCN(3-2), and HCO+(3-2) line data obtained with the APEX telescope to study the properties of the molecular gas in the nebula and the IRAS source . To analyze the properties and distribution of the dust, we used IRAC-GLIMPSE, Herschel, and ATLASGAL data. The properties of the ionized gas were studied using images obtained from the SUMSS survey and SuperCOSMOS database. In our search for stellar and protostellar objects in the region, we used IR and optical point source calalogs. The new APEX observations allowed us to identify three molecular components associated with the nebula, namely: at $-$39 km/s (component A), $-$25 km/s (component B), and $-$17 km/s (component C). Six molecular condensations (MC1 to MC6) were identified in component A, with MC3 (the densest and more massive one) being the molecular counterpart of IRAS12326-6245. For this source, we estimated an H$_2$ column density up to 8$\times$10$^{23}$ cm$^{-2}$. To explain the morphology and velocity of components A, B, and C, we propose a simple model consisting of a partially complete semisphere-like structure expanding at ~ 12 km/s. The introduction of this model has led to a discussion about the distance to both S169 and IRAS12326-6245, which was estimated to be ~ 2 kpc. Several candidate YSOs were identified, projected mostly onto the molecular condensations MC3, MC4, and MC5, which indicates that the star-formation process is very active at the borders of the nebula. A comparison between observable and modeled parameters was not enough to discern whether the collect-and-collapse mechanism is acting at the edge of S169.

astro-ph.GA↗

arXiv2020

Molecular environments of the supernova remnant G359.1-0.5

We report new CO observations and a detailed molecular-line study of the mixed morphology (MM) supernova remnant (SNR) G359.1-0.5, which contains six OH (1720 MHz) masers along the radio shell, indicative of shock-cloud interaction. Observations of 12CO and 13CO J:1-0 lines were performed in a 38x38 arcmin area with the on-the-fly technique using the Kit Peak 12 Meter telescope. The molecular study has revealed the existence of a few clumps with densities around 1,000 cm$^{-3}$ compatible in velocity and position with the OH (1720 MHz) masers. These clumps, in turn, appear to be part of a larger, elongated molecular structure ~34 arcmin long extending between -12.48 and +1.83 km/s, adjacent to the western edge of the radio shell. According to the densities and relative position with respect to the masers, we conclude that the CO clouds depict unshocked gas, as observed in other remnants with OH (1720 MHz) masers. In addition, we investigated the distribution of the molecular gas towards the adjacent gamma-ray source HESS J1745-303 but could not find any morphological correlation between the gamma-rays and the CO emission at any velocity in this region.

astro-ph.GA↗

arXiv2019

Possible Evidence for Cosmic-Ray Acceleration in the Type Ia SNR RCW 86: Spatial Correlation between TeV Gamma rays and Interstellar Atomic Protons

We present a detailed morphological study of TeV gamma rays, synchrotron radiation, and interstellar gas in the young Type Ia supernova remnant (SNR) RCW 86. We find that the interstellar atomic gas shows good spatial correlation with the gamma rays, indicating that the TeV gamma rays from RCW 86 are likely to be dominantly of hadronic origin. In contrast, the spatial correlation between the interstellar molecular cloud and the TeV gamma rays is poor in the southeastern shell of the SNR. We argue that this poor correlation can be attributed to the low-energy cosmic rays (~ 1 TeV) not penetrating into the dense molecular cloud due to an enhancement of the turbulent magnetic field around the dense cloud of ~ 10-100 $μ$G. We also find that the southwestern shell, which is bright in both synchrotron X-ray and radio continuum radiation, shows a significant gamma-ray excess compared with the interstellar proton column density, suggesting that leptonic gamma rays via inverse Compton scattering possibly contributes along with hadronic gamma rays. The total cosmic-ray energies of the young TeV gamma-ray SNRs$-$RX J1713.7$-$3946, Vela Jr, HESS J1731$-$347, and RCW 86$-$are roughly similar, which indicates that cosmic rays can be accelerated in both the core-collapse and Type Ia supernovae. The total energy of cosmic rays derived using the gas density, ~ 10$^{48}$-10$^{49}$ erg, gives a safe lower limit due mainly to the low filling factor of interstellar gas within the shell.

astro-ph.HE↗

arXiv2018

New perspectives on the supernova remnant Puppis A based on a radio polarization study

We present a polarization study towards the supernova remnant (SNR) Puppis A based on original observations performed with the Australia Telescope Compact Array (ATCA). Based on the analysis of a feature detected outside the SNR shell (called `the tail' throughout the paper), it was possible to disentangle the emission with origin in Puppis A itself from that coming from the foreground Vela SNR. We found a very low polarization fraction, of about 3 percent on average. The upper limit of the magnetic field component parallel to the line of sight is estimated to be B$_\parallel \sim$ 20 $μ$G. The statistical behavior of the magnetic vectors shows two preferential directions, almost perpendicular to each other, which are approximately aligned with the flat edges of Puppis A. A third, narrow peak oriented perpendicular to the Galactic plane suggests the existence of an interstellar magnetic field locally aligned in this direction. There is evidence that the magnetic vectors along the shell are aligned with the shock front direction. The low polarization fraction and the statistical behavior of the magnetic vectors are compatible with a scenario where the SNR evolves inside a stellar wind bubble with a box-like morphology, produced by the interaction of the different stellar winds, one of them magnetized, launched by the SN progenitor. This scenario can furthermore explain the morphology of Puppis A, rendering little support to the previously accepted picture which involved strong density gradients to explain the flat, eastern edge of the shell.

astro-ph.HE↗

arXiv2017

A multi-wavelength analysis of the diffuse HII region G25.8700+0.1350

We present a multiwavelength investigation of the HII region G25.8700+0.1350, located in the inner part of the Galaxy. In radio continuum emission, the region is seen as a bright arc-shaped structure. An analysis of the HI line suggests that G25.8700+0.1350 lies at a distance of 6.5 kpc. The ionized gas is bordered by a photodissociation region which is encircled by a molecular structure where four molecular clumps are detected. At infrared wavelengths, the region is also very conspicuous. Given the high level of visual absorption in the region, the exciting stars should be searched for in the infrared band. In this context, we found in the literature one Wolf-Rayet and one red supergiant which, together with 37 2MASS sources candidates to be O-type stars, could be related to the origin of G25.8700+0.1350. Finally, as expanding HII regions are hypothesized to trigger star formation, we used different infrared point source catalogues to search for young stellar object candidates (cYSOs). A total of 45 cYSOs were identified projected onto the molecular clouds.

astro-ph.GA↗

arXiv2017

Interstellar Gas and X-rays toward the Young Supernova Remnant RCW 86; Pursuit of the Origin of the Thermal and Non-Thermal X-ray

We have analyzed the atomic and molecular gas using the 21 cm HI and 2.6/1.3 mm CO emissions toward the young supernova remnant (SNR) RCW 86 in order to identify the interstellar medium with which the shock waves of the SNR interact. We have found an HI intensity depression in the velocity range between $-46$ and $-28$ km s$^{-1}$ toward the SNR, suggesting a cavity in the interstellar medium. The HI cavity coincides with the thermal and non-thermal emitting X-ray shell. The thermal X-rays are coincident with the edge of the HI distribution, which indicates a strong density gradient, while the non-thermal X-rays are found toward the less dense, inner part of the HI cavity. The most significant non-thermal X-rays are seen toward the southwestern part of the shell where the HI gas traces the dense and cold component. We also identified CO clouds which are likely interacting with the SNR shock waves in the same velocity range as the HI, although the CO clouds are distributed only in a limited part of the SNR shell. The most massive cloud is located in the southeastern part of the shell, showing detailed correspondence with the thermal X-rays. These CO clouds show an enhanced CO $J$ = 2-1/1-0 intensity ratio, suggesting heating/compression by the shock front. We interpret that the shock-cloud interaction enhances non-thermal X-rays in the southwest and the thermal X-rays are emitted by the shock-heated gas of density 10-100 cm$^{-3}$. Moreover, we can clearly see an HI envelope around the CO cloud, suggesting that the progenitor had a weaker wind than the massive progenitor of the core-collapse SNR RX J1713.7$-$3949. It seems likely that the progenitor of RCW 86 was a system consisting of a white dwarf and a low-mass star with low-velocity accretion winds.

astro-ph.HE↗

arXiv2017

A 3D MHD simulation of SN 1006: a polarized emission study for the turbulent case

Three dimensional magnetohydrodynamical simulations were carried out in order to perform a new polarization study of the radio emission of the supernova remnant SN 1006. These simulations consider that the remnant expands into a turbulent interstellar medium (including both magnetic field and density perturbations). Based on the referenced-polar angle technique, a statistical study was done on observational and numerical magnetic field position-angle distributions. Our results show that a turbulent medium with an adiabatic index of 1.3 can reproduce the polarization properties of the SN 1006 remnant. This statistical study reveals itself as a useful tool for obtaining the orientation of the ambient magnetic field, previous to be swept up by the main supernova remnant shock.

astro-ph.HE↗

arXiv2016

A high resolution HI study towards the supernova remnant Puppis A and its environments

We observed the supernova remnant (SNR) Puppis A in the 21 cm line with the Australia Telescope Compact Array with the aim of determining the systemic velocity and, hence, the corresponding kinematic distance. For the compact, background sources in the field, we obtain absorption spectra by applying two methods: (a) subtracting profiles on- and off-source towards continuum emission, and (b) filtering short spacial frequencies in the Fourier plane to remove large scale emission. One of the brightest features to the East of the shell of Puppis A was found to be a background source, probably extragalactic. Removing the contribution from this and the previously known unrelated sources, the systemic velocity of Puppis A turns out to be limited between 8 and 12 km s$^{-1}$, which places this source at a distance of 1.3 $\pm$ 0.3 kpc. From the combined images that include both single dish and interferometric data, we analyze the distribution of the interstellar hydrogen. We suggest that an ellipsoidal ring at $v \sim $+8 km s$^{-1}$ could be the relic of a bubble blown by the progenitor of Puppis A, provided the distance is $\lesssim$ 1.2 kpc. The main consequences of the new systemic velocity and distance as compared with previous publications ($v =$ +16 km s$^{-1}$ and $d = $2.2 kpc) are the absence of a dense interacting cloud to the East to explain the morphology, and the decrease of the shell size and the neutron star velocity, which are now in better agreement with statistical values.

astro-ph.GA↗

arXiv2015

Radio spectral characteristics of the supernova remnant Puppis A and nearby sources

This paper presents a new study of the spectral index distribution of the supernova remnant (SNR) Puppis A. The nature of field compact sources is also investigated according to the measured spectral indices. This work is based on new observations of Puppis A and its surroundings performed with the Australia Telescope Compact Array in two configurations using the Compact Array Broad-band Backend centered at 1.75 GHz. We find that the global spectral index of Puppis A is -0.563 +/- 0.013. Local variations have been detected, however this global index represents well the bulk of the SNR. At the SE, we found a pattern of parallel strips with a flat spectrum compatible with small-scale filaments, although not correlated in detail. The easternmost filament agrees with the idea that the SN shock front is interacting with an external cloud. There is no evidence of the previously suggested correlation between emissivity and spectral index. A number of compact features are proposed to be evolved clumps of ejecta based on their spectral indices, although dynamic measurements are needed to confirm this hypothesis. We estimate precise spectral indices for the five previously known field sources, two of which are found to be double (one of them, probably triple), and catalogue 40 new sources. In the light of these new determinations, the extragalactic nature previously accepted for some compact sources is now in doubt.

astro-ph.GA↗

arXiv2015

3D MHD simulation of polarized emission in SN 1006

We use three dimensional magnetohydrodynamic (MHD) simulations to model the supernova remnant SN 1006. From our numerical results, we have carried out a polarization study, obtaining synthetic maps of the polarized intensity, the Stokes parameter $Q$, and the polar-referenced angle, which can be compared with observational results. Synthetic maps were computed considering two possible particle acceleration mechanisms: quasi-parallel and quasi-perpendicular. The comparison of synthetic maps of the Stokes parameter $Q$ maps with observations proves to be a valuable tool to discern unambiguously which mechanism is taking place in the remnant of SN 1006, giving strong support to the quasi-parallel model.

astro-ph.HE↗

arXiv2010

An MHD study of SN 1006 and determination of the ambient magnetic field direction

In this work we employ an MHD numerical code to reproduce the morphology observed for SN 1006 in radio synchrotron and thermal X-ray emission. We introduce a density discontinuity, in the form of a flat cloud parallel to the Galactic Plane, in order to explain the NW filament observed in optical wavelengths and in thermal X-rays. We compare our models with observations. We also perform a test that contrasts the radio emitting bright limbs of the SNR against the central region, finding additional support to our results. Our main conclusion is that the most probable direction of the ambient magnetic field is on average perpendicular to the Galactic Plane.

astro-ph.SR↗

arXiv2009

Accounting for the Foreground Contribution to the Dust Emission towards Kepler's Supernova Remnant

Whether or not supernovae contribute significantly to the overall dust budget is a controversial subject. Submillimetre (submm) observations, sensitive to cold dust, have shown an excess at 450 and 850 microns in young remnants Cassiopeia A (Cas A) and Kepler. Some of the submm emission from Cas A has been shown to be contaminated by unrelated material along the line of sight. In this paper we explore the emission from material towards Kepler using submm continuum imaging and spectroscopic observations of atomic and molecular gas, via HI, 12CO (J=2-1) and 13CO (J=2-1). We detect weak CO emission (peak TA* = 0.2-1K, 1-2km/s fwhm) from diffuse, optically thin gas at the locations of some of the submm clumps. The contribution to the submm emission from foreground molecular and atomic clouds is negligible. The revised dust mass for Kepler's remnant is 0.1--1.2 solar masses, about half of the quoted values in the original study by Morgan et al. (2003), but still sufficient to explain the origin of dust at high redshifts.

astro-ph.GA↗

arXiv2006

G332.5-5.6, a new Galactic supernova remnant

We present radio observations of the source G332.5-5.6, a candidate supernova remnant (SNR). Observations have been performed with the Australia Telescope Compact Array (ATCA) at two frequencies, at 1.4 and 2.4 GHz. Our results confirm that G332.5-5.6 is an SNR, with a spectral index equal to -0.7 +/- 0.2 for the whole source and an average fractional polarization of ~35% at 2.4 GHz. The central component is coincident with extended X-ray emission and the distance to the SNR is estimated to be ~3.4 kpc. Based on its radio and X-ray morphology, this SNR should be classified as a composite, and we suggest that it belongs to a trident-shaped subclass like G291.0-0.1.

astro-ph↗

arXiv2005

The interior of the SNR RX J0852.0-4622 (Vela Jr) at radio wavelengths

Aim: We observed the center of the supernova remnant Vela Jr in radio continuum in order to search for a counterpart to the compact central X-ray source CXOU J085201.4-461753, possibly a neutron star candidate which could be the remnant of the supernova explosion. Method: Observations were made with the Australia Telescope Compact Array at 13 and 20 cm. Spectral indices were obtained using flux density correlations of the data which were spatially filtered to have the same u-v coverage. A multiwavelength search for counterparts to the compact central X-ray source was made. Results: We compiled a new catalogue of 31 small diameter radio sources, including the previously known source PMN J0853-4620, listing the integrated flux densities at 20 cm and, for half of the sources, the flux densities at 13 cm with the corresponding spectral indices. All sources are unresolved at the present angular resolution except for Source 18, which is clearly elongated and lies strikingly close to CXOU J085201.4-461753. Our observations show no evidence for the existence of a pulsar wind driven nebula associated with the point X-ray source. Furthermore, Source 18 has a thermal spectrum with index +0.8 +/- 0.4, and appears to be the counterpart of the optical source Wray 16-30. In spite of the absence of OIII emission lines as reported in the literature, we find that this object could be explained as a low emission planetary nebula belonging to the ``butterfly'' morphological class. Conclusions: We conclude that if the radio source 18 is actually a planetary nebula, then CXOU J085201.4-461753 is more likely to be related to it rather than to Vela Jr.

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