The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope... more The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed an increasing gamma-ray flux from a source positionally consistent with B2 1520+31 (RA: 15 22 09.99 , Dec: +31 44 14.4 , J2000, A. J. Beasley et al. 2002, ApJS, 41, 13) since April 20, 2009.
The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (fo... more The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed, since April 25th, 2009, a flare from a gamma-ray source positionally consistent with the blazar PKS 1510-089 (RA:15h12m50.5329s, Dec:-09d05m59.828s, redshift 0.360 and already known as an EGRET gamma-ray source, 3EG J1512-0849). Preliminary analysis indicates that on 25th April the source was in a high state with a gamma-ray flux (E>100MeV) of 6.5+/-0.7e-6 cm^-2 s^-1 (statistical only) in the daily time scale and it reached a value of 8.2+/-1.9e-6 cm^-2 s^-1 (statistical only) in the 6-hours interval starting at 06:00 UT of the same day.
The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high ... more The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high energy gamma-ray astrophysics in the 30 MeV-50 GeV range, with a window in the hard-X domain 18-60 keV. One of the on-board detectors, the Mini-Calorimeter (MCAL), was also designed to work as all sky transient monitor in the energy range 0.33-100 MeV. Though
We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IG... more We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Tele- scope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predic- tions compared to previous work. More specifically, we estimate the cosmologically- induced gamma-ray intensity to have an uncertainty of a factor ∼ 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former on the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies....
ABSTRACT Working memory (WM) is fundamental for a number of cognitive processes, such as comprehe... more ABSTRACT Working memory (WM) is fundamental for a number of cognitive processes, such as comprehension, reasoning and learning. WM allows the short-term maintenance and manipulation of the information selected by attentional processes. The goal of this study was to examine by time-resolved fNIRS neural correlates of the verbal and visual WM during forward and backward digit span (DF and DB, respectively) tasks, and symbol span (SS) task. A neural dissociation was hypothesised between the maintenance and manipulation processes. In particular, a dorsolateral/ventrolateral prefrontal cortex (DLPFC/VLPFC) recruitment was expected during the DB task, whilst a lateralised involvement of Brodmann Area (BA) 10 was expected during the execution of the DF task. Thirteen subjects were monitored by a multi-channel, dual-wavelength (690 and 829 nm) time-resolved fNIRS system during 3 minutes long DF and DB tasks and 4 minutes long SS task. The participants' mean memory span was calculated for each task: DF: 6.46+/-1.05 digits; DB: 5.62+/-1.26 digits; SS: 4.69+/-1.32 symbols. No correlation was found between the span level and the heart rate data (measured by pulse oximeter). As expected, DB elicited a broad activated area, in the bilateral VLPFC and the right DLPFC, whereas a more localised activation was observed over the right hemisphere during either DF (BA 10) or SS (BA 10 and 44). The robust involvement of the DLPFC during DB, compared to DF, is compatible with previous findings and with the key role of the central executive subserving in manipulating processes.
ABSTRACT We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 M... more ABSTRACT We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope... more The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed an increasing gamma-ray flux from a source positionally consistent with B2 1520+31 (RA: 15 22 09.99 , Dec: +31 44 14.4 , J2000, A. J. Beasley et al. 2002, ApJS, 41, 13) since April 20, 2009.
The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (fo... more The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed, since April 25th, 2009, a flare from a gamma-ray source positionally consistent with the blazar PKS 1510-089 (RA:15h12m50.5329s, Dec:-09d05m59.828s, redshift 0.360 and already known as an EGRET gamma-ray source, 3EG J1512-0849). Preliminary analysis indicates that on 25th April the source was in a high state with a gamma-ray flux (E>100MeV) of 6.5+/-0.7e-6 cm^-2 s^-1 (statistical only) in the daily time scale and it reached a value of 8.2+/-1.9e-6 cm^-2 s^-1 (statistical only) in the 6-hours interval starting at 06:00 UT of the same day.
The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high ... more The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high energy gamma-ray astrophysics in the 30 MeV-50 GeV range, with a window in the hard-X domain 18-60 keV. One of the on-board detectors, the Mini-Calorimeter (MCAL), was also designed to work as all sky transient monitor in the energy range 0.33-100 MeV. Though
We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IG... more We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Tele- scope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predic- tions compared to previous work. More specifically, we estimate the cosmologically- induced gamma-ray intensity to have an uncertainty of a factor ∼ 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former on the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies....
ABSTRACT Working memory (WM) is fundamental for a number of cognitive processes, such as comprehe... more ABSTRACT Working memory (WM) is fundamental for a number of cognitive processes, such as comprehension, reasoning and learning. WM allows the short-term maintenance and manipulation of the information selected by attentional processes. The goal of this study was to examine by time-resolved fNIRS neural correlates of the verbal and visual WM during forward and backward digit span (DF and DB, respectively) tasks, and symbol span (SS) task. A neural dissociation was hypothesised between the maintenance and manipulation processes. In particular, a dorsolateral/ventrolateral prefrontal cortex (DLPFC/VLPFC) recruitment was expected during the DB task, whilst a lateralised involvement of Brodmann Area (BA) 10 was expected during the execution of the DF task. Thirteen subjects were monitored by a multi-channel, dual-wavelength (690 and 829 nm) time-resolved fNIRS system during 3 minutes long DF and DB tasks and 4 minutes long SS task. The participants' mean memory span was calculated for each task: DF: 6.46+/-1.05 digits; DB: 5.62+/-1.26 digits; SS: 4.69+/-1.32 symbols. No correlation was found between the span level and the heart rate data (measured by pulse oximeter). As expected, DB elicited a broad activated area, in the bilateral VLPFC and the right DLPFC, whereas a more localised activation was observed over the right hemisphere during either DF (BA 10) or SS (BA 10 and 44). The robust involvement of the DLPFC during DB, compared to DF, is compatible with previous findings and with the key role of the central executive subserving in manipulating processes.
ABSTRACT We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 M... more ABSTRACT We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.
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Papers by Sara Cutini