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X-WR-CALNAME:Osservatorio Astronomico di Roma
X-ORIGINAL-URL:https://www.oa-roma.inaf.it
X-WR-CALDESC:Eventi per Osservatorio Astronomico di Roma
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DTSTART:20160327T010000
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DTSTART:20161030T010000
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DTSTART:20170326T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170404T114500
DTEND;TZID=Europe/Rome:20170404T124500
DTSTAMP:20260516T133102
CREATED:20160915T091316Z
LAST-MODIFIED:20160915T091316Z
UID:1545-1491306300-1491309900@www.oa-roma.inaf.it
SUMMARY:The dust mass in Cassiopeia A from spatially resolved Herschel photometry
DESCRIPTION:The large reservoirs of dust observed in some high redshift galaxies have been hypothesised to originate from dust produced by supernovae from massive stars. Theoretical models predict that core-collapse supernovae (CCSN) can be efficient dust producers (0.1-1 Msun) potentially responsible for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g.\, SN1987A\, Crab Nebula) that confirm this scenario.  \nWe revisit the dust mass produced in Cassiopeia A (Cas A)\, a ~330-year old O-rich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ~0.6 arcmin for this 5arcmin diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 micron with a four-component interstellar medium (ISM) and supernova (SN) dust model.  \nWe find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5 Msun of silicate grains freshly produced in the SNR. For a mixture of 50% of silicate-type grains and 50% of carbonaceous grains\, we derive a total SN dust mass between 0.4 Msun and 0.6 Msun. These dust masses estimates are higher than from most previous studies of Cas A and support the scenario of supernova dominated dust production at high redshifts. Our resolved analysis shows that the cold SN dust component is mainly distributed interior to the reverse shock of Cas A\, suggesting that part of the newly formed dust has already been destroyed by the reverse shock. We furthermore derive an interstellar extinction map which towards Cas A gives average values of AV=6-8 mag\, up to a maximum of AV=15 mag.
URL:https://www.oa-roma.inaf.it/event/seminario-6/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170404T114500
DTEND;TZID=Europe/Rome:20170404T124500
DTSTAMP:20260516T133102
CREATED:20160915T091316Z
LAST-MODIFIED:20160915T091316Z
UID:4688-1491306300-1491309900@www.oa-roma.inaf.it
SUMMARY:The dust mass in Cassiopeia A from spatially resolved Herschel photometry
DESCRIPTION:The large reservoirs of dust observed in some high redshift galaxies have been hypothesised to originate from dust produced by supernovae from massive stars. Theoretical models predict that core-collapse supernovae (CCSN) can be efficient dust producers (0.1-1 Msun) potentially responsible for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g.\, SN1987A\, Crab Nebula) that confirm this scenario.  \nWe revisit the dust mass produced in Cassiopeia A (Cas A)\, a ~330-year old O-rich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ~0.6 arcmin for this 5arcmin diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 micron with a four-component interstellar medium (ISM) and supernova (SN) dust model.  \nWe find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5 Msun of silicate grains freshly produced in the SNR. For a mixture of 50% of silicate-type grains and 50% of carbonaceous grains\, we derive a total SN dust mass between 0.4 Msun and 0.6 Msun. These dust masses estimates are higher than from most previous studies of Cas A and support the scenario of supernova dominated dust production at high redshifts. Our resolved analysis shows that the cold SN dust component is mainly distributed interior to the reverse shock of Cas A\, suggesting that part of the newly formed dust has already been destroyed by the reverse shock. We furthermore derive an interstellar extinction map which towards Cas A gives average values of AV=6-8 mag\, up to a maximum of AV=15 mag.
URL:https://www.oa-roma.inaf.it/event/seminario-6-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170411T114500
DTEND;TZID=Europe/Rome:20170411T124500
DTSTAMP:20260516T133103
CREATED:20161114T095627Z
LAST-MODIFIED:20161114T095627Z
UID:1981-1491911100-1491914700@www.oa-roma.inaf.it
SUMMARY:Unveiling the most elusive star-forming galaxies
DESCRIPTION:Our knowledge of the cosmic star formation history is crucially dependent on completeness of the observed samples\, and the best efforts must be made to ensure the best completeness levels against two classes of sources: intrinsically faint galaxies and heavily dust-obscured ones.\nIn the first part of the talk I will show recent results on the relation between the SFR and the stellar mass\, i.e. the Main Sequence (MS) relation of star-forming galaxies\, in the HST Frontier Fields. Gravitational lensing allows us to extend the analysis of the MS down to stellar masses as low as 10^7.5 Msun at z<4 and 10^8 Msun at higher redshift\, i.e. a factor of ~10 below previous results. I will show that the scatter around the MS increases at such low stellar masses\, suggesting a larger variety of star formation histories\, in agreement with theoretical predictions.\nIn the second part of the talk I will present a detailed study of a representative of the elusive dust-enshrouded star-forming population that is typically not included in the measured SFH nor in the stellar mass density. Thanks to ALMA data\, an apparently extremely dust-rich galaxy turned out to be a faint submillimeter galaxy (SMG) lensed by a foreground source and completely obscured at optical wavelengths. A photo-z of z~3.3 and the physical parameters are estimated thanks to an accurate reconstruction of the SED. With a SFR lower than 300 Msun/yr\, this galaxy belongs to the class of faint SMGs (S870um~2.5mJy) that are important contributors to the cosmic SFH. This faint galaxy population thus likely represents an important and missing piece of our understanding of the cosmic SFH and galaxy evolution.
URL:https://www.oa-roma.inaf.it/event/seminario-paola-santini/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170411T114500
DTEND;TZID=Europe/Rome:20170411T124500
DTSTAMP:20260516T133103
CREATED:20161114T095627Z
LAST-MODIFIED:20161114T095627Z
UID:4700-1491911100-1491914700@www.oa-roma.inaf.it
SUMMARY:Unveiling the most elusive star-forming galaxies
DESCRIPTION:Our knowledge of the cosmic star formation history is crucially dependent on completeness of the observed samples\, and the best efforts must be made to ensure the best completeness levels against two classes of sources: intrinsically faint galaxies and heavily dust-obscured ones.\nIn the first part of the talk I will show recent results on the relation between the SFR and the stellar mass\, i.e. the Main Sequence (MS) relation of star-forming galaxies\, in the HST Frontier Fields. Gravitational lensing allows us to extend the analysis of the MS down to stellar masses as low as 10^7.5 Msun at z<4 and 10^8 Msun at higher redshift\, i.e. a factor of ~10 below previous results. I will show that the scatter around the MS increases at such low stellar masses\, suggesting a larger variety of star formation histories\, in agreement with theoretical predictions.\nIn the second part of the talk I will present a detailed study of a representative of the elusive dust-enshrouded star-forming population that is typically not included in the measured SFH nor in the stellar mass density. Thanks to ALMA data\, an apparently extremely dust-rich galaxy turned out to be a faint submillimeter galaxy (SMG) lensed by a foreground source and completely obscured at optical wavelengths. A photo-z of z~3.3 and the physical parameters are estimated thanks to an accurate reconstruction of the SED. With a SFR lower than 300 Msun/yr\, this galaxy belongs to the class of faint SMGs (S870um~2.5mJy) that are important contributors to the cosmic SFH. This faint galaxy population thus likely represents an important and missing piece of our understanding of the cosmic SFH and galaxy evolution.
URL:https://www.oa-roma.inaf.it/event/seminario-paola-santini-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170418T114500
DTEND;TZID=Europe/Rome:20170418T124500
DTSTAMP:20260516T133103
CREATED:20170208T080753Z
LAST-MODIFIED:20170208T080753Z
UID:4705-1492515900-1492519500@www.oa-roma.inaf.it
SUMMARY:Elemental Abundances across Cosmic Time
DESCRIPTION:I show how chemical enrichment took place in the Milky Way and in a cosmic scale\, using my hydrodynamical simulations that includes star formation and feedback from stars\, supernovae\, and active galactic nuclei (AGN). Thanks to nuclear astro-physics collaboration\, we now have good understanding of the origin of elements from carbon to zinc\, and theoretical models have well reproduced the observations of these elemental abundances in the Milky Way Galaxy. Some new observations challenge these models for a few elements\, which is due to the problems in stellar astrophysics. In our cosmological simulations\, we also include super-massive blackholes that originate the first stars\, which had only ~100-1000 Msun initially\, contrary to the merger products in other simulations. Our AGN cause large-scale metal outflows\, which result in the enrichment of intergalactic medium\, as well as the quenching of star formation in massive galaxies. The simulated results are in good agreement with many observations of galaxies\, including cosmic star formation rates\, blackhole mass-galaxy mass relation\, size-mass relation\, and mass-metallicity relations of galaxies (which evolve with a steeper slope at higher redshifts)\, and metallicity radial gradients within galaxies (which can trace the merging history of the galaxies). I also show elemental abundances at high-redshift galaxies\, which can be used to understand the formation and evolution of galaxies.
URL:https://www.oa-roma.inaf.it/event/talk-by-chiaki-kobayashi-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170418T114500
DTEND;TZID=Europe/Rome:20170418T124500
DTSTAMP:20260516T133103
CREATED:20170208T080753Z
LAST-MODIFIED:20170208T080753Z
UID:2438-1492515900-1492519500@www.oa-roma.inaf.it
SUMMARY:Elemental Abundances across Cosmic Time
DESCRIPTION:I show how chemical enrichment took place in the Milky Way and in a cosmic scale\, using my hydrodynamical simulations that includes star formation and feedback from stars\, supernovae\, and active galactic nuclei (AGN). Thanks to nuclear astro-physics collaboration\, we now have good understanding of the origin of elements from carbon to zinc\, and theoretical models have well reproduced the observations of these elemental abundances in the Milky Way Galaxy. Some new observations challenge these models for a few elements\, which is due to the problems in stellar astrophysics. In our cosmological simulations\, we also include super-massive blackholes that originate the first stars\, which had only ~100-1000 Msun initially\, contrary to the merger products in other simulations. Our AGN cause large-scale metal outflows\, which result in the enrichment of intergalactic medium\, as well as the quenching of star formation in massive galaxies. The simulated results are in good agreement with many observations of galaxies\, including cosmic star formation rates\, blackhole mass-galaxy mass relation\, size-mass relation\, and mass-metallicity relations of galaxies (which evolve with a steeper slope at higher redshifts)\, and metallicity radial gradients within galaxies (which can trace the merging history of the galaxies). I also show elemental abundances at high-redshift galaxies\, which can be used to understand the formation and evolution of galaxies.
URL:https://www.oa-roma.inaf.it/event/talk-by-chiaki-kobayashi/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170426T114500
DTEND;TZID=Europe/Rome:20170426T124500
DTSTAMP:20260516T133103
CREATED:20170126T085350Z
LAST-MODIFIED:20170126T085350Z
UID:4704-1493207100-1493210700@www.oa-roma.inaf.it
SUMMARY:The detection of magnetic waves in the solar atmosphere\, using the Sun as plasma physics laboratory.
DESCRIPTION:The Sun is one of our best plasma physics laboratory. The recent direct identification of magnetic waves in the solar atmosphere (i.e. Alfvén and alfvénic waves) is an example of how the Sun can be exploited to advance plasma physics research. In this talk\, starting from this recent discovery\, I will discuss the implications that these new results can have in a number of fields\, from astrophysics to fusion research. Further\, I will briefly discuss what to expect from the next generation solar telescopes (DKIST and EST).
URL:https://www.oa-roma.inaf.it/event/talk-by-marco-stangalini-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20170426T114500
DTEND;TZID=Europe/Rome:20170426T124500
DTSTAMP:20260516T133103
CREATED:20170126T085350Z
LAST-MODIFIED:20170126T085350Z
UID:2371-1493207100-1493210700@www.oa-roma.inaf.it
SUMMARY:The detection of magnetic waves in the solar atmosphere\, using the Sun as plasma physics laboratory.
DESCRIPTION:The Sun is one of our best plasma physics laboratory. The recent direct identification of magnetic waves in the solar atmosphere (i.e. Alfvén and alfvénic waves) is an example of how the Sun can be exploited to advance plasma physics research. In this talk\, starting from this recent discovery\, I will discuss the implications that these new results can have in a number of fields\, from astrophysics to fusion research. Further\, I will briefly discuss what to expect from the next generation solar telescopes (DKIST and EST).
URL:https://www.oa-roma.inaf.it/event/talk-by-marco-stangalini/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
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