| 1. |
- Alberdi, Antxon, et al.
(författare)
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The jet of the Low Luminosity AGN of M81. Evidence of Precession
- 2013
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 61
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Konferensbidrag (refereegranskat)abstract
- In this contribution, we summarize our main results of a big campaign of global VLBI observations of the AGN in M81 (M81*) phase-referenced to the radio supernova SN 1993J. Thanks to the precise multi-epoch and multi-frequency astrometry, we have determined the normalized core-shift of the relativistic jet of M81* and estimated both the magnetic field and the particle density at the jet base. We have also found evidence of jet precession in M81* coming from the systematic time evolution of the jet orientation correlated with changes in the overall flux density.
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| 2. |
- Beswick, R. J., et al.
(författare)
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SKA studies of nearby galaxies: Star-formation, accretion processes and molecular gas across all environments
- 2014
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Ingår i: Proceedings of Science. - 1824-8039. ; 9-13-June-2014
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Konferensbidrag (refereegranskat)abstract
- The SKA will be a transformational instrument in the study of our local Universe. In particular, by virtue of its high sensitivity (both to point sources and diffuse low surface brightness emission), angular resolution and the frequency ranges covered, the SKA will undertake a very wide range of astrophysical research in the field of nearby galaxies. By surveying vast numbers of nearby galaxies of all types with mJy sensitivity and sub-arcsecond angular resolutions at radio wavelengths, the SKA will provide the cornerstone of our understanding of star-formation and accretion activity in the local Universe. In this chapter we outline the key continuum and molecular line science areas where the SKA, both during phase-1 and when it becomes the full SKA, will have a significant scientific impact.
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| 3. |
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| 4. |
- Marti-Vidal, Ivan, 1980, et al.
(författare)
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Jet precession in the active nucleus of M81. Ongoing VLBI monitoring
- 2012
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Ingår i: Proceedings of Science. - 1824-8039. ; 2012-October
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Konferensbidrag (refereegranskat)abstract
- In a recent publication, we reported results of a multi-frequency VLBI campaign of observations of the Active Galactic Nucleus (AGN) in galaxy M\,81, phase-referenced to the supernova SN\,1993J. We were able to extract precise information on the relative astrometry of the AGN radio emission at different epochs and frequencies. We found strong evidence of precession in the AGN jet (i.e., a systematic evolution in the jet inclination at each frequency) coupled to changes in the overall flux density at the different frequencies. In these proceedings, we summarise the main contents of our previous publication and we report on (preliminary) new results from our follow-up VLBI observations, now phase-referenced to the young supernova SN2008iz. We also briefly discuss how these results match the picture of our previously-reported precession model.
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| 5. |
- Perez-Torres, Miguel Angel, et al.
(författare)
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Constraining the progenitor of the type Ia SN 2014J with the EVN and eMERLIN
- 2014
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Ingår i: Proceedings of Science. - 1824-8039.
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Konferensbidrag (refereegranskat)abstract
- We report the deepest radio interferometric observations of the closest Type Ia supernova in decades, SN 2014J, which exploded in the nearby galaxy M 82. These observations represent, together with radio observations of SNe 2011fe, the most sensitive radio studies of a Type Ia SN ever. We constrain the mass-loss rate from the progenitor system of SN 2014J to M ≲ 7.0 × 10-10 M⊙yr-1 (for a wind speed of 100 km s-1). Most single-degenerate scenarios, i.e., the wide family of progenitor systems where a red giant, main-sequence, or sub-giant star donates mass to a exploding white dwarf, are ruled out by our observations. On the contrary, our stringent upper limits to the radio emission from SN 2014 favor a double-degenerate scenario-involving two WD stars-for the progenitor system of SN 2014J, as such systems have less circumstellar gas than our upper limits. Thus, the evidence from SNe 2011fe and 2014J points in the direction of a double-degenerate scenario for both. Looking into the future, we note that the huge improvement in sensitivity of the SKA with respect to its predecessors will allow us to determine which progenitor scenario (single-degenerate vs. double-degenerate) applies to a large sample of nearby Type Ia SNe, thus unambiguously solving this issue. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
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| 6. |
- Perez-Torres, Miguel Angel, et al.
(författare)
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Core-collapse and type ia supernovae with the SKA
- 2014
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Ingår i: Proceedings of Science. - 1824-8039. ; 9-13-June-2014
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Konferensbidrag (refereegranskat)abstract
- Core-collapse SNe (CCSNe): Systematic searches of radio emission from CCSNe are still lacking, and only targeted searches of radio emission from just some of the optically discovered CCSNe in the local universe have been carried out. Optical searches miss a significant fraction of CCSNe due to dust obscuration; CCSN radio searches are thus more promising for yielding the complete, unobscured star-formation rates in the local universe. The SKA yields the possibility to piggyback for free in this area of research by carrying out commensal, wide-field, blind transient survey observations. SKA1-SUR should be able to discover several hundreds of CCSNe in just one year, compared to about a dozen CCSNe that the VLASS would be able to detect in one year, at most. SKA, with an expected sensitivity ten times that of SKA1, is expected to detect CCSNe in the local Universe by the thousands. Therefore, commensal SKA observations could easily result in an essentially complete census of all CCSNe in the local universe, thus yielding an accurate determination of the volumetric CCSN rate. Type Ia SNe: We advocate for the use of the SKA to search for the putative prompt (first few days after the explosion) radio emission of any nearby type Ia SN, via target-of-opportunity observations. The huge improvement in sensitivity of the SKA with respect to its predecessors will allow to unambiguously discern which progenitor scenario (single-degenerate vs. double-degenerate) applies to them.
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| 7. |
- Perez-Torres, Miguel Angel, et al.
(författare)
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What is the progenitor of the Type Ia SN 2014J?
- 2014
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Ingår i: Proceedings of the 11th Scientific Meeting of the Spanish Astronomical Society - Highlights of Spanish Astrophysics VIII, SEA 2014. ; , s. 540-546
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Konferensbidrag (refereegranskat)abstract
- We report the deepest radio interferometric observations of the closest Type Ia supernova in decades, SN 2014J, which exploded in the nearby galaxy M 82. These observations represent, together with radio observations of SNe 2011fe, the most sensitive radio studies of a Type Ia SN ever. We constrain the mass-loss rate from the progenitor system of SN 2014J lower than 7.0 × 10^(−10) M yr^(−1) (for a wind speed of 100 km s^(−1) ). Our deep upper limits favor a double-degenerate scenario–involving two WD stars–for the progenitor system of SN 2014J, as such systems have less circumstellar gas than our upper limits. By contrast, most single-degenerate scenarios, i.e., the wide family of progenitor systems where a red giant, main-sequence, or sub-giant star donates mass to a exploding white dwarf, are ruled out by our observations. The evidence from SNe 2011fe and 2014J points in the direction of a double-degenerate scenario for both.
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| 8. |
- Ramirez-Olivencia, Naim, et al.
(författare)
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EVN imaging of the LIRGI sample
- 2014
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Ingår i: Proceedings of Science. - 1824-8039.
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Konferensbidrag (refereegranskat)abstract
- The central few hundred parsecs of Ultra/Luminous Infrared Galaxies (U/LIRGs) are hidden from view at most wavelengths due to the presence of large amounts of dust. Very Long Baseline Interferometry (VLBI) observations are a powerful tool to unveil the nature of the sources beyond dust clouds. In fact, radio observations are unaffected by dust, and thanks to the high angular resolution are able to pinpoint the compact components in the central regions of U/LIRGs. Thus, VLBI observations can potentially disentangle the dominant mechanism responsible for the dust heating in U/LIRGs, i.e., an Active Galactic Nucleus (AGN), or a starburst, or a combination of both. In this contribution we present preliminary results for 12 galaxies from the Luminous Infrared Galaxy Inventory (LIRGI) sample, obtained from observations with the European VLBI Network (EVN) at 6 and 18 cm. We show images from NGC 2623 and Mrk 331. Mrk 331 shows three relatively faint compact components at C-band, consistent with emission from young supernovae and/or supernova remnants. On the contrary, NGC 2623 shows a single, very bright compact component at both wavelengths and a very inverted spectral index, clearly indicating that this is the AGN. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
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