P. Benaglia | Universidad Nacional de La Plata (original) (raw)
Papers by P. Benaglia
Astronomy & Astrophysics - ASTRON ASTROPHYS, 1995
Westerbork Synthesis Radio Telescope HI observations combined with Effelsberg 100m antenna observ... more Westerbork Synthesis Radio Telescope HI observations combined with Effelsberg 100m antenna observations have been made of the galactic supernova remnant 3C 10 (Tycho) with an angular resolution =~50" and a velocity resolution of 0.62km/s and with the VLA with resolutions of ~13" and 1.3km/s, respectively. HI absorption against 3C 10 was detected in the velocity range -60<=v<=10km/s. The most negative velocity component is at -57km/s. HI absorption in the direction of extragalactic source 3C11.1 and two additional sources close to 3C 10 (distance <~1deg) was obtained using the Very Large Array. Comparison of the spectra together with two other sources from Taylor & Roberts (1993) (distance <~2deg) leads to the conclusion that 3C 10 is at a distance of 4.5kpc. The implications of this distance are discussed. The HI absorption at -48km/s in the direction of 3C 10 shows a filament of size ~4'. Self-absorption near 3C 10 is also detected at this velocity, and a...
Bulletin of the …, 1999
Title: Radio Fields Around Unidentified EGRET Sources. Authors: Combi, JA; Romero, GE; Benaglia, ... more Title: Radio Fields Around Unidentified EGRET Sources. Authors: Combi, JA; Romero, GE; Benaglia, P.; Azcarate, IN. Affiliation ... Vol. 31, p.723. Publication Date: 04/1999. Origin: AAS. Bibliographic Code: 1999HEAD....4.2102C. Abstract. ...
Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar... more Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar wind in the subclass of massive X-ray binaries known as ``microquasars''. The relativistic jet is ejected from the surroundings of the compact object and interacts with cold protons from the stellar wind, producing pions that then quickly decay into gamma-rays. Since the resulting
Astronomy and Astrophysics, 2004
We present the results of radio continuum observations towards the open cluster Tr 14, where our ... more We present the results of radio continuum observations towards the open cluster Tr 14, where our main targets are the early-type O stars HD 93129A/B and HD 93128. The observations were carried out at 3 cm (8.64 GHz) and 6 cm (4.80 GHz) with the Australia Telescope Compact Array. Only HD 93129A (type O2 If*) was detected; we measure flux densities of S 3 cm = 2.0 ± 0.2 mJy and S 6 cm = 4.1 ± 0.4 mJy. The resulting spectral index of α = −1.2 ± 0.3 (S ν ∝ ν α ) indicates predominantly non-thermal emission, suggesting HD 93129A may be a binary system. We propose that the observed 3 cm radio emission is mostly coming from the non-thermal wind collision region of a binary, and, to a lesser extent, from the thermal winds of the primary and secondary stars in HD 93129A. At a stellar distance of 2.8 kpc, we derive a mass-loss ratė M = 5.1 × 10 −5 M yr −1 , assuming the thermal fraction of the 3 cm emission is ∼0.5.
The O2 If* star HD 93129A, the brightest member of the Tr 14 cluster in Carina, has recently been... more The O2 If* star HD 93129A, the brightest member of the Tr 14 cluster in Carina, has recently been observed as a strong non-thermal radio emitter (Benaglia & Koribalski 2005, C678), with a 1.4 GHz flux of ~10 mJy. Also recently, Nelan et al. (2004) using FGS-HST data, have demonstrated that this star has an O-star companion 55 mas distant
We are using HST GO programs 10205, 10602, and 10898 to test the stellar upper mass limit in the ... more We are using HST GO programs 10205, 10602, and 10898 to test the stellar upper mass limit in the solar vicinity by attempting to detect optical close companions, thus lowering the calculated evolutionary masses. We have observed with ACS/HRC all the known (as of early 2005) Galactic O2/3/3.5 stars. We also have observations with HST/FGS and ground-based spectroscopy from LCO
We present observational evidence supporting a pic- ture where the -ray source 2EGS J1703-6302 is... more We present observational evidence supporting a pic- ture where the -ray source 2EGS J1703-6302 is the result of the interaction between cosmic rays (CRs) accelerated in a super- nova remnant (SNR) and a nearby HI cloud. The SNR has been disclosed by filtering the diffuse disk emission from new 1.42 GHz continuum observations of the radio field around 2EGS J1703-6302.
We present the results of a spatial correlation analysis between unidentified gamma-ray sources i... more We present the results of a spatial correlation analysis between unidentified gamma-ray sources in the 3EG catalog and candidates to supernova remnants. This work extends a previous study made by Romero, Benaglia & Torres (1999). We also consider the gamma-ray emission variability and the spectral index for the sources with positional coincidence.
The structure and kinematics of the interstellar medium (ISM) are strongly modified by the action... more The structure and kinematics of the interstellar medium (ISM) are strongly modified by the action of stellar winds from massive stars which create interstellar bubbles. These structures can be detected as slowly expanding neutral shells in the HIemission distribution around O and WR stars (e.g. Cappa & Benaglia 1998; Cappa 2006).
Astronomy & Astrophysics, 2015
Context. Stellar bow shocks have been studied not only observationally, but also theoretically si... more Context. Stellar bow shocks have been studied not only observationally, but also theoretically since the late 1980s. Only a few catalogues of them exist. The bow shocks show emission along all the electromagnetic spectrum, but they are detected more easily in infrared wavelengths. The release of new and high-quality infrared data eases the discovery and subsequent study of new objects. Aims. We search stellar bow-shock candidates associated with nearby runaway stars, and gather them together with those found elsewhere, to enlarge the list of the E-BOSS first release. We aim to characterize the bow-shock candidates and provide a database suitable for statistical studies. We investigate the low-frequency radio emission at the position of the bow-shock features, that can contribute to further studies of high-energy emission from these objects. Methods. We considered samples from different literature sources and searched for bow-shaped structures associated with stars in the Wide-field Infrared Survey Explorer (WISE) images. We looked for each bow-shock candidate on centimeter radio surveys. Results. We reunited 45 bow-shock candidates and generated composed WISE images to show the emission in different infrared bands. Among them there are new sources, previously studied objects, and bow shocks found serendipitously. Five bow shocks show evidence of radio emission. Conclusions. Stellar bow shocks constitute an active field with open questions and enormous amounts of data to be analyzed. Future research at all wavelengths databases, and use of instruments like Gaia, will provide a more complete picture of these objects. For instance, infrared spectral energy distributions can give information about physical parameters of the bow shock matter. In addition, dedicated high-sensitivity radio observations can help to understand the radio-γ connection.
Publications of the Astronomical Society of Australia, 2006
Four massive, early-type stars, three of which are confirmed binaries, have been observed with th... more Four massive, early-type stars, three of which are confirmed binaries, have been observed with the Australia Telescope Compact Array at 1.4, 2.4, 4.8, and 8.6 GHz. The earliest star cataloged so far, HD 93129A, was also observed at 17.8 and 24.5 GHz. Here we present an analysis of the spectra as well as the structure of the stellar systems. All four spectra show clear evidence of non-thermal emission, indicative of a binary system with a colliding wind region. We discuss the magnetic field of the emitting region of HD 93129A and make predictions on the radiation at high energies. Archive X-ray observations towards the target sources are also investigated and interpreted in the light of the non-thermal emission detected.
In a recent paper, have presented the results of a positional correlation analysis of the low-lat... more In a recent paper, have presented the results of a positional correlation analysis of the low-latitude unidentified gamma-ray sources in the Third EGRET catalog with complete lists of galactic objects like supernova remnants, early type stars with strong stellar winds, and OB associations (considered as pulsar tracers). We have now carried out a study of those 42 sources at |b| < 10 • for which no counterpart was found at all. A variability analysis shows that this sample contains a population of sources with high levels of variability at gammarays. The surface density of these variable sources is 5 times higher than what is expected for unidentified AGNs seen through the Galactic plane. We discuss the origin of this presumed Galactic population of gamma-ray objects and the role that INTEGRAL could play in their physical identification.
We present the results of a spatial correlation analysis between unidentified gamma-ray sources i... more We present the results of a spatial correlation analysis between unidentified gamma-ray sources in the 3EG catalog and candidates to supernova remnants. This work extends a previous study made by . We also consider the gamma-ray emission variability and the spectral index for the sources with positional coincidence.
We present results of intraday variability observations at 5 GHz of the EGRET blazars 0202+14, 02... more We present results of intraday variability observations at 5 GHz of the EGRET blazars 0202+14, 0235+16, 2230+11, and 2251+15. The BL-Lac object 0235+16 presented flux density variations of ∼ 7 % over timescales of ∼ 1.3 days. The source 0202+14 was also variable, although with smaller amplitudes. The behaviour of 0235+16 at short timescales is almost identical to that presented in previous intraday observations carried out in 1990, when the flux density of the source was 4 times higher. We discuss the possible origin of the ultra rapid radio variability in these sources within different possible scenarios.
Astronomy & Astrophysics - ASTRON ASTROPHYS, 1995
Westerbork Synthesis Radio Telescope HI observations combined with Effelsberg 100m antenna observ... more Westerbork Synthesis Radio Telescope HI observations combined with Effelsberg 100m antenna observations have been made of the galactic supernova remnant 3C 10 (Tycho) with an angular resolution =~50" and a velocity resolution of 0.62km/s and with the VLA with resolutions of ~13" and 1.3km/s, respectively. HI absorption against 3C 10 was detected in the velocity range -60<=v<=10km/s. The most negative velocity component is at -57km/s. HI absorption in the direction of extragalactic source 3C11.1 and two additional sources close to 3C 10 (distance <~1deg) was obtained using the Very Large Array. Comparison of the spectra together with two other sources from Taylor & Roberts (1993) (distance <~2deg) leads to the conclusion that 3C 10 is at a distance of 4.5kpc. The implications of this distance are discussed. The HI absorption at -48km/s in the direction of 3C 10 shows a filament of size ~4'. Self-absorption near 3C 10 is also detected at this velocity, and a...
Bulletin of the …, 1999
Title: Radio Fields Around Unidentified EGRET Sources. Authors: Combi, JA; Romero, GE; Benaglia, ... more Title: Radio Fields Around Unidentified EGRET Sources. Authors: Combi, JA; Romero, GE; Benaglia, P.; Azcarate, IN. Affiliation ... Vol. 31, p.723. Publication Date: 04/1999. Origin: AAS. Bibliographic Code: 1999HEAD....4.2102C. Abstract. ...
Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar... more Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar wind in the subclass of massive X-ray binaries known as ``microquasars''. The relativistic jet is ejected from the surroundings of the compact object and interacts with cold protons from the stellar wind, producing pions that then quickly decay into gamma-rays. Since the resulting
Astronomy and Astrophysics, 2004
We present the results of radio continuum observations towards the open cluster Tr 14, where our ... more We present the results of radio continuum observations towards the open cluster Tr 14, where our main targets are the early-type O stars HD 93129A/B and HD 93128. The observations were carried out at 3 cm (8.64 GHz) and 6 cm (4.80 GHz) with the Australia Telescope Compact Array. Only HD 93129A (type O2 If*) was detected; we measure flux densities of S 3 cm = 2.0 ± 0.2 mJy and S 6 cm = 4.1 ± 0.4 mJy. The resulting spectral index of α = −1.2 ± 0.3 (S ν ∝ ν α ) indicates predominantly non-thermal emission, suggesting HD 93129A may be a binary system. We propose that the observed 3 cm radio emission is mostly coming from the non-thermal wind collision region of a binary, and, to a lesser extent, from the thermal winds of the primary and secondary stars in HD 93129A. At a stellar distance of 2.8 kpc, we derive a mass-loss ratė M = 5.1 × 10 −5 M yr −1 , assuming the thermal fraction of the 3 cm emission is ∼0.5.
The O2 If* star HD 93129A, the brightest member of the Tr 14 cluster in Carina, has recently been... more The O2 If* star HD 93129A, the brightest member of the Tr 14 cluster in Carina, has recently been observed as a strong non-thermal radio emitter (Benaglia & Koribalski 2005, C678), with a 1.4 GHz flux of ~10 mJy. Also recently, Nelan et al. (2004) using FGS-HST data, have demonstrated that this star has an O-star companion 55 mas distant
We are using HST GO programs 10205, 10602, and 10898 to test the stellar upper mass limit in the ... more We are using HST GO programs 10205, 10602, and 10898 to test the stellar upper mass limit in the solar vicinity by attempting to detect optical close companions, thus lowering the calculated evolutionary masses. We have observed with ACS/HRC all the known (as of early 2005) Galactic O2/3/3.5 stars. We also have observations with HST/FGS and ground-based spectroscopy from LCO
We present observational evidence supporting a pic- ture where the -ray source 2EGS J1703-6302 is... more We present observational evidence supporting a pic- ture where the -ray source 2EGS J1703-6302 is the result of the interaction between cosmic rays (CRs) accelerated in a super- nova remnant (SNR) and a nearby HI cloud. The SNR has been disclosed by filtering the diffuse disk emission from new 1.42 GHz continuum observations of the radio field around 2EGS J1703-6302.
We present the results of a spatial correlation analysis between unidentified gamma-ray sources i... more We present the results of a spatial correlation analysis between unidentified gamma-ray sources in the 3EG catalog and candidates to supernova remnants. This work extends a previous study made by Romero, Benaglia & Torres (1999). We also consider the gamma-ray emission variability and the spectral index for the sources with positional coincidence.
The structure and kinematics of the interstellar medium (ISM) are strongly modified by the action... more The structure and kinematics of the interstellar medium (ISM) are strongly modified by the action of stellar winds from massive stars which create interstellar bubbles. These structures can be detected as slowly expanding neutral shells in the HIemission distribution around O and WR stars (e.g. Cappa & Benaglia 1998; Cappa 2006).
Astronomy & Astrophysics, 2015
Context. Stellar bow shocks have been studied not only observationally, but also theoretically si... more Context. Stellar bow shocks have been studied not only observationally, but also theoretically since the late 1980s. Only a few catalogues of them exist. The bow shocks show emission along all the electromagnetic spectrum, but they are detected more easily in infrared wavelengths. The release of new and high-quality infrared data eases the discovery and subsequent study of new objects. Aims. We search stellar bow-shock candidates associated with nearby runaway stars, and gather them together with those found elsewhere, to enlarge the list of the E-BOSS first release. We aim to characterize the bow-shock candidates and provide a database suitable for statistical studies. We investigate the low-frequency radio emission at the position of the bow-shock features, that can contribute to further studies of high-energy emission from these objects. Methods. We considered samples from different literature sources and searched for bow-shaped structures associated with stars in the Wide-field Infrared Survey Explorer (WISE) images. We looked for each bow-shock candidate on centimeter radio surveys. Results. We reunited 45 bow-shock candidates and generated composed WISE images to show the emission in different infrared bands. Among them there are new sources, previously studied objects, and bow shocks found serendipitously. Five bow shocks show evidence of radio emission. Conclusions. Stellar bow shocks constitute an active field with open questions and enormous amounts of data to be analyzed. Future research at all wavelengths databases, and use of instruments like Gaia, will provide a more complete picture of these objects. For instance, infrared spectral energy distributions can give information about physical parameters of the bow shock matter. In addition, dedicated high-sensitivity radio observations can help to understand the radio-γ connection.
Publications of the Astronomical Society of Australia, 2006
Four massive, early-type stars, three of which are confirmed binaries, have been observed with th... more Four massive, early-type stars, three of which are confirmed binaries, have been observed with the Australia Telescope Compact Array at 1.4, 2.4, 4.8, and 8.6 GHz. The earliest star cataloged so far, HD 93129A, was also observed at 17.8 and 24.5 GHz. Here we present an analysis of the spectra as well as the structure of the stellar systems. All four spectra show clear evidence of non-thermal emission, indicative of a binary system with a colliding wind region. We discuss the magnetic field of the emitting region of HD 93129A and make predictions on the radiation at high energies. Archive X-ray observations towards the target sources are also investigated and interpreted in the light of the non-thermal emission detected.
In a recent paper, have presented the results of a positional correlation analysis of the low-lat... more In a recent paper, have presented the results of a positional correlation analysis of the low-latitude unidentified gamma-ray sources in the Third EGRET catalog with complete lists of galactic objects like supernova remnants, early type stars with strong stellar winds, and OB associations (considered as pulsar tracers). We have now carried out a study of those 42 sources at |b| < 10 • for which no counterpart was found at all. A variability analysis shows that this sample contains a population of sources with high levels of variability at gammarays. The surface density of these variable sources is 5 times higher than what is expected for unidentified AGNs seen through the Galactic plane. We discuss the origin of this presumed Galactic population of gamma-ray objects and the role that INTEGRAL could play in their physical identification.
We present the results of a spatial correlation analysis between unidentified gamma-ray sources i... more We present the results of a spatial correlation analysis between unidentified gamma-ray sources in the 3EG catalog and candidates to supernova remnants. This work extends a previous study made by . We also consider the gamma-ray emission variability and the spectral index for the sources with positional coincidence.
We present results of intraday variability observations at 5 GHz of the EGRET blazars 0202+14, 02... more We present results of intraday variability observations at 5 GHz of the EGRET blazars 0202+14, 0235+16, 2230+11, and 2251+15. The BL-Lac object 0235+16 presented flux density variations of ∼ 7 % over timescales of ∼ 1.3 days. The source 0202+14 was also variable, although with smaller amplitudes. The behaviour of 0235+16 at short timescales is almost identical to that presented in previous intraday observations carried out in 1990, when the flux density of the source was 4 times higher. We discuss the possible origin of the ultra rapid radio variability in these sources within different possible scenarios.