Osservatorio Astrofisico di Arcetri
AstroBignÓ? seminars season 2014-2015
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Last updated by S. Zibetti, Sept. 18th, 2015
Tuesday 30th June 2015 - 11:45 Aula A
Luca Del Zanna [ASAP (UniFi)] (High Energy)
Alfven waves in the expanding solar wind
The (fast) solar wind turbulent plasma is dominated by Alfvenic fluctuations propagating away from the Sun, with physical properties depending on the heliocentric distance. Here I will discuss the fate of (monochromatic) Alfven waves in such expanding environment via numerical MHD simulations.
The (fast) solar wind turbulent plasma is dominated by Alfvenic fluctuations propagating away from the Sun, with physical properties depending on the heliocentric distance. Here I will discuss the fate of (monochromatic) Alfven waves in such expanding environment via numerical MHD simulations.
Simone Landi [ASAP (UniFi)] (High Energy)
ò??Idealò??-magnetic reconnection in Magnethydrodynamics: implications for explosive phenomena in Astrophysical plasmas
On how non-ideal instabilities can trigger explosive phenomena in ideal time scales: the ò??idealò?? tearing mode.
On how non-ideal instabilities can trigger explosive phenomena in ideal time scales: the ò??idealò?? tearing mode.
Stefano Carniani (Extragalactic)
Fast outflows quenching star formation at high redshift
Negative feedback from accreting black holes is considered a fundamental physical process in galaxy evolution. It is indeed to provide the link between the growth of supermassive black holes and their host galaxies. The [OIII]ÞË5007 line emission is a good tracer of outflows and ionized gas dynamics in the narrow-line regions of AGN. I will present VLT-SINFONI near-IR integral field spectra of five quasar at redshift z=2.4. The kinematical analysis of the [OIII] line shows complex gas kinematics in a region of several kpc from the location of the AGN, with blue shifted velocities of a few hundreds of km/s and line widths up to 1500 km/s. [OIII] emission likely traces a massive outflow with a conical morphology. Furthermore we detect the presence of faint, narrow (< 200 km/s) [OIII] emission anti correlated with the presence of the fast blue shifted [OIII]. Overall, our data are consistent with a picture in which narrow [OIII] emission traces star forming gas in the host galaxy, which is absent in the conical outflows, as expected when fast outflows quench star formation. This scenario is confirmed by the observations of the Ha emission, tracing star formation in the host galaxy, which is strongly suppressed in the outflows region. Finally, I will present AGN feedback model to describe the ionized gas dynamic and the properties of outflows.
Negative feedback from accreting black holes is considered a fundamental physical process in galaxy evolution. It is indeed to provide the link between the growth of supermassive black holes and their host galaxies. The [OIII]ÞË5007 line emission is a good tracer of outflows and ionized gas dynamics in the narrow-line regions of AGN. I will present VLT-SINFONI near-IR integral field spectra of five quasar at redshift z=2.4. The kinematical analysis of the [OIII] line shows complex gas kinematics in a region of several kpc from the location of the AGN, with blue shifted velocities of a few hundreds of km/s and line widths up to 1500 km/s. [OIII] emission likely traces a massive outflow with a conical morphology. Furthermore we detect the presence of faint, narrow (< 200 km/s) [OIII] emission anti correlated with the presence of the fast blue shifted [OIII]. Overall, our data are consistent with a picture in which narrow [OIII] emission traces star forming gas in the host galaxy, which is absent in the conical outflows, as expected when fast outflows quench star formation. This scenario is confirmed by the observations of the Ha emission, tracing star formation in the host galaxy, which is strongly suppressed in the outflows region. Finally, I will present AGN feedback model to describe the ionized gas dynamic and the properties of outflows.
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Tuesday 16th June 2015 - 11:45 Aula A
Sperello di Serego Alighieri
Fiat Lux
Highlights from the Conference "Fiat Lux" held in Rome on June 3-5, 2015
Highlights from the Conference "Fiat Lux" held in Rome on June 3-5, 2015
Edvige Corbelli (Extragalactic)
IGM@50 Is the Intergalactic Medium Driving Star Formation?
Highlights from the conference held in Spineto June 8th-12th, 2015
Highlights from the conference held in Spineto June 8th-12th, 2015
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Tuesday 5th May 2015 - 11:45 Aula A
Elena Masciadri (Techno)
Forecasts of the OT as a support to the ground-based astronomy supported by AO facilities: state of art at Arcetri
In this contribution I will briefly present the state of art of the studies and projects we are carrying on in Arcetri in the context of the forecast of the optical turbulence and atmospherical parameters conceived as a tool to support the ground-based astronomy particularly that assisted by the AO. With ALTA and MOSE we are going towards the setting-up of automatic operational systems for LBT, VLT and the E-ELT. With STARMET we are investigating, in collaboration with LaMMA, the possibility to set-up in Florence an advanced center for the OT forecasts at different top-class telescopes in the world.
In this contribution I will briefly present the state of art of the studies and projects we are carrying on in Arcetri in the context of the forecast of the optical turbulence and atmospherical parameters conceived as a tool to support the ground-based astronomy particularly that assisted by the AO. With ALTA and MOSE we are going towards the setting-up of automatic operational systems for LBT, VLT and the E-ELT. With STARMET we are investigating, in collaboration with LaMMA, the possibility to set-up in Florence an advanced center for the OT forecasts at different top-class telescopes in the world.
Giovanni Morlino (High Energy)
Effect of mass loading in bow shock nebulae
Bow shock pulsar wind nebulae show highly non-smooth tail structures in HÞÁ, radio and X-rays. We investigate the long term dynamics of the bow shock nebulae created by pulsars moving supersonically through partially ionized interstellar medium. Ionization of neutrals penetrating into the pulsar wind tail and the resulting mass loading changes dramatically the flow dynamics of a light leptonic pulsar wind. The photo-ionization by the UV light produced enough massloading to strongly affect the tail flow. Using a quasi 1-D approximation, we find that mass loading leads to the fast expansion of the pulsar wind tail, making the tail flow intrinsically non-stationary. The resulting shapes of pulsar bow shock nebulae, in HÞÁ radio and X-rays, compare favorably with observations.
Bow shock pulsar wind nebulae show highly non-smooth tail structures in HÞÁ, radio and X-rays. We investigate the long term dynamics of the bow shock nebulae created by pulsars moving supersonically through partially ionized interstellar medium. Ionization of neutrals penetrating into the pulsar wind tail and the resulting mass loading changes dramatically the flow dynamics of a light leptonic pulsar wind. The photo-ionization by the UV light produced enough massloading to strongly affect the tail flow. Using a quasi 1-D approximation, we find that mass loading leads to the fast expansion of the pulsar wind tail, making the tail flow intrinsically non-stationary. The resulting shapes of pulsar bow shock nebulae, in HÞÁ radio and X-rays, compare favorably with observations.
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Tuesday 21st April 2015 - 11:45 Aula A
Sperello di Serego (General physics & astrophysics)
The Equivalence Principle from Galileo to Einstein
I will briefly discuss the historical and conceptual evolution of the equivalence principle from Galileo (involving just moving bodies and implying the equivalence of gravitational and inertial mass) to Einstein (involving also electrodynamics and constituting the foundation of General Relativity).
I will briefly discuss the historical and conceptual evolution of the equivalence principle from Galileo (involving just moving bodies and implying the equivalence of gravitational and inertial mass) to Einstein (involving also electrodynamics and constituting the foundation of General Relativity).
Runa Briguglio (Techno)
E-ELT M4 on the go: optical test of the Demonstration Prototype
The M4 is the deformable mirror for the european ELT and has just enter the MAIT phase (manufacturing, integration and test), led by the italian consortium AdOptica. The M4 is a system composed by a 2.6 m diameter monolithic reference plate, 6 thin glass shells, 5316 actuators providing 1 kHz, 100um stroke for the high order adaptive correction. A Demonstration Prototype (M4DP) with two sub-shells has been assembled to allow the verification of the technological updates (with respect to the LBT and VLT mirrors) and of the functioning and testing procedures for the M4. The M4DP was optically calibrated at INAF Merate by a working group led by Arcetri: the optical test allowed to flatten, align and co-phase the shells at the requested 20 nm RMS Wavefront accuracy; also, specific procedures for the M4 calibration were tested. In this AstroBignÓ? presentation I will summarize the optical test activity on the M4DP, looking forward to start again on the M4.
The M4 is the deformable mirror for the european ELT and has just enter the MAIT phase (manufacturing, integration and test), led by the italian consortium AdOptica. The M4 is a system composed by a 2.6 m diameter monolithic reference plate, 6 thin glass shells, 5316 actuators providing 1 kHz, 100um stroke for the high order adaptive correction. A Demonstration Prototype (M4DP) with two sub-shells has been assembled to allow the verification of the technological updates (with respect to the LBT and VLT mirrors) and of the functioning and testing procedures for the M4. The M4DP was optically calibrated at INAF Merate by a working group led by Arcetri: the optical test allowed to flatten, align and co-phase the shells at the requested 20 nm RMS Wavefront accuracy; also, specific procedures for the M4 calibration were tested. In this AstroBignÓ? presentation I will summarize the optical test activity on the M4DP, looking forward to start again on the M4.
Francesco Fontani (Star Formation)
Deuterated molecules as unexpected chemical tracers for shocks
The process of deuterium enrichment in molecules from the main reservoir HD is initiated in molecular clouds by exothermic gas-phase reactions. For this reason, deuterated molecules have long been used as tracers of the coldens and densest portions of molecular clouds. Although this general framework remains true, the story is not so simple. Based on the results recently obtained with mm interferometers (PdBI and ALMA), I will show observational evidence that deuterated molecules are also excellent tracers of recently shocked regions (i.e. regions in a completely different physical regime), under peculiar circumstances.
The process of deuterium enrichment in molecules from the main reservoir HD is initiated in molecular clouds by exothermic gas-phase reactions. For this reason, deuterated molecules have long been used as tracers of the coldens and densest portions of molecular clouds. Although this general framework remains true, the story is not so simple. Based on the results recently obtained with mm interferometers (PdBI and ALMA), I will show observational evidence that deuterated molecules are also excellent tracers of recently shocked regions (i.e. regions in a completely different physical regime), under peculiar circumstances.
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Tuesday 31 March 2015 - 11:45 Aula A
Riccardo Cesaroni (Star Formation)
New Light from HII Regions
Ionized regions around early-type stars are believed to be well known objects, but surprises are still possible. In this short presentation I will describe an unexpected result that was obtained from the comparison of the radio and IR emission of young HII regions and will explain how such a finding might shed (new) light on the O-B star formation process itself.
Ionized regions around early-type stars are believed to be well known objects, but surprises are still possible. In this short presentation I will describe an unexpected result that was obtained from the comparison of the radio and IR emission of young HII regions and will explain how such a finding might shed (new) light on the O-B star formation process itself.
Francesco Palla et al.
Astrofrontiere 2015
A report of the recent "general assembly" of INAF about the future of astrophysics in Italy. After the intro by Francesco Palla, open time for reports by other participants and discussion.
A report of the recent "general assembly" of INAF about the future of astrophysics in Italy. After the intro by Francesco Palla, open time for reports by other participants and discussion.
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Tuesday 10th March 2015 - 11:45 Aula A
Marco Bocchio (Extragalactic)
Dust Processing and Evolution in Extreme Environments
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Antonio Pili (High Energy)
Twisted Magnetosphere in General