AGILE Top Results

Dec 30, 2016

50000 orbits of AGILE celebrated with the observation of an exceptional gamma-ray event
A few months before its tenth birthday in orbit, on December 19, 2016 at 06:08:53 UTC the AGILE satellite has reached the significant milestone of 50000 passes over the ASI Malindi Ground Station in Kenya with all detectors operating nominally.

AGILE is devoted to gamma-ray astrophysics, and it is also capable of detecting high energy phenomena of terrestrial nature, such as Terrestrial Gamma-ray Flashes (TGFs) revealed in the Earth equatorial regions. It is also currently at the forefront in the hunt for electromagnetic counterparts of gravitational waves.

The Italian satellite, launched on April 23, 2007 in low Earth orbit, is a small Scientific Mission of ASI, built and operated in cooperation with INAF, INFN, CIFS and with the participation of the Italian companies CGS, Thales-Alenia Space e Telespazio.

The small high-tech jewel, designed for an operative life of only two years, continues its mission with high efficiency, and it has celebrated its 50000 orbit with the observation of an exceptional gamma-ray event of extragalactic origin.

Credits: Screenshot downloaded on December 19, 2016 from the AGILEScience free app dedicated to the AGILE satellite.

As you can see from the fascinating image above, two monsters black holes at the center of the two distant active galactic nuclei CTA 102 and 3C 454.3, apparently close to each other in the AGILE sky map, made a spectacular double super-flare almost simultaneously in gamma rays.

The image was downloaded from the AGILEScience free app that enables anyone to follow in real time the latest satellite observations.

In particular, the CTA 102 source in these days was the brightest of the entire gamma-ray sky, even brighter than much closer sources within our galaxy, such as the Vela pulsar.

For more information, see also:
ASI news and INAF news (in Italian)
AGILE ATel #9743, ATel #9788, ATel #9840, ATel #9911 and references therein.

The AGILE data acquired from the ASI Malindi Ground Station are readily processed archived and managed by the SSDC/ASDC, the multi-mission ASI data center, and distributed to the PI Team alert system at INAF Bologna. The automatic alerts are analyzed daily by researchers of the AGILE team at several INAF institutes and at the ASDC itself.

May 29, 2015

AGILE: 8 and counting
"AGILE: 8 and counting", this was the title of the 13th AGILE Workshop celebrating the eighth anniversary of the launch of the AGILE satellite.

Since its launch on 23 April 2007, AGILE has made several important scientific discoveries, such as the variability of the Crab Nebula in gamma-rays, and the existence of a high-energy component in terrestrial gamma-ray flashes (TGF) produced in the Earth atmosphere.

The 13th AGILE Workshop was held in the ASI Headquarters on May 25-26, 2015. The slides of all contributions are publicly available at the workshop website.

A special ASI-TV report by G. Pulcrano was dedicated to AGILE in this occasion. The video (in italian) can be viewed here.

CREDITS: ASI-TV report by Giuseppina Pulcrano, ASI-TV Chief Editor: Manuela Proietti, Video Editor: Daniele Quatrini.

Mar 26, 2014

AGILE mission operations extended by ASI for another year
After a 3-month 'stand-by' period, during which the AGILE scientific observations were suspended, today the satellite started to look at the gamma-ray sky again. Following the positive evaluation of the scientific results in its first 6 years of operations, and the still nominal status, as evaluated by the AGILE Mission Board, the Italian Space Agency decided to extend the operations of AGILE for additional 12 months.
The animation below shows the first day of data acquisition after the operations restart.

A petition supporting the protraction of the AGILE Mission was started autonomously by a Princeton physicist, Franco Paoletti and by Bruno Coppi, Prof. Emeritus at MIT, working in the area of Plasma Physics. The third signature is the one of the Nobel Prize Russell Hulse, discoverer of the first binary pulsar. Their interest in the AGILE Mission stems from the discovery of the variability of the Crab Nebula in gamma-rays, which earned the 2012 Bruno Rossi Prize to Marco Tavani and the AGILE team. As of today the petition reached almost 500 signatures from all over the world.
A manifestation of interest and a strong support letter was also sent to ASI by the Terrestrial atmospheric science community, interested in the unique contribution that AGILE is giving to the science of Terrestrial Gamma Ray Flashes (TGF).
The first scientific data after the restart has been successfully received and processed today at the AGILE Data Center at ASDC.

Thank to the hundreds of supporters that signed the petition "AGILE Must Go On". Click here to access the current list of signatures

Nov 12, 2013

GRB 131108A in gamma-rays
GRB 131108A, bright but relatively soft in gamma-rays, triggered onboard Fermi-LAT (GCN #15464), and transited in the field of view of AGILE approximately between -20 and +150 seconds from the trigger (t0 = 20:41:55 UT) (GCN #15479). A preliminary reduction of the optical afterglow spectrum indicates a GRB redshift of z=2.40 (GCN #15470).

This is the first onboard Fermi-LAT trigger since 2009, indicating a potentially rare and interesting event. The autonomous repoint of the Fermi spacecraft of 9ksec was followed by a ToO pointed observation until about 23:11 UT of November 9, 2013. The Fermi LAT data flow and quality monitor during this exciting GRB was followed by a duty shifter scientist of ASDC.

A preliminary analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data in temporal and spatial coincidence with the GRB shows a significant excess of gamma-ray events above 30 MeV at the location of the event.

AGILE-GRID detected more than 65 photons compatible with the GRB location in the anticygnus region, most of which below 100 MeV, corresponding to a fluence of 2.56 +- 0.32 1e-5 erg / cm^2 in the energy band 30 MeV - 1 GeV, in which AGILE has a competitive sensitivity.

The AGILE-GRID image of GRB 131108A, one of the most interesting GRB events seen by AGILE after 6 years of observations, is shown in the figure below.

Image: AGILE-GRID view of GRB 131108A , credits AGILE Team.

Jan 16, 2013

Award ceremony of the Bruno Rossi prize 2012 to Marco Tavani and the AGILE Team.
The ceremony for the 2012 "Bruno Rossi" prize, awarded to Marco Tavani and the AGILE Team, was held in Long Beach, CA, on January 10, 2013, during the American Astronomical Society (AAS) 221 Meeting.

The prestigious High Energy Astrophysics Division (HEAD) Rossi prize has been awarded to AGILE for the unexpected discovery in 2010 of strong and rapid gamma-ray flares from the Crab Nebula over daily timescales (M. Tavani et al., Science vol. 331, 2011). Long thought to be a steady source of radiation, from optical to gamma rays, the AGILE findings have changed the understanding of this cosmic object, and challenged emission models of pulsar wind and particle acceleration processes.

The discovery of flaring activity from the Crab nebula was made possible also thanks to the sky monitoring capability and fast ground segment alert system of the AGILE satellite, which also observed a previous flare from the Crab Nebula in October, 2007, reported in the First AGILE source catalog as a possible unexpected brief flux increase (Pittori et al., A&A 506, 2009).

The Rossi Prize lecture: "The Flaring Crab Nebula: Surprises and Challenges" given by Marco Tavani on behalf of the AGILE mission team was among the AAS 221 conference highlights.

See also: AGILE poster presented at the AAS meeting and (in Italian): ASI news, INAF news, INAF-TV Video

January 12, 2012

AGILE wins the 2012 "Bruno Rossi prize", the fourth time that a mission supported by ASDC is given this important award!
We are proud to announce that the 2012 "Bruno Rossi prize" of the High Energy Astrophysics Division of the American Astronomical Society has been awarded to "Marco Tavani and the AGILE team for the discovery of gamma-ray flares from the Crab Nebula."

AGILE ("Astrorivelatore Gamma a Immagini Leggero") is an Italian space mission dedicated to the observation of the gamma-ray Universe. Despite the small size and budget, AGILE, thanks to its scientific team led by the PI Marco Tavani, produced several important scientific results, among which the discovery of strong flares from the Crab Nebula and the characterization of Terrestrial Gamma-rays Flashes.

This is the fourth time that a space mission in which the ASDC plays an important role has been awarded a "Bruno Rossi prize", after BeppoSAX in 1998, Swift in 2007 and Fermi in 2011.

During 2010 the AGILE discovery of Crab Nebula variability above 100 MeV has astonished the scientific community (M. Tavani et al., Science vol. 331, 2011). Astronomers have always believed the Crab to be a constant source from optical to gamma-ray energies: an ideal standard candle.
However, on September 2010, AGILE detected a giant gamma-ray flare, and thanks to its rapid alert system, made the first public announcement on September 22, 2010. This finding was confirmed the next day by the Fermi Observatory (A. Abdo et al., Science vol. 331, 2011).

A previous flare from the Crab Nebula was observed by AGILE in October, 2007 and reported in the First AGILE source catalog as a possible unexpected flux increase (Pittori et al., A&A 506, 2009).

Funded by ASI, AGILE was built and is operated in cooperation with INAF and INFN, with the participation of CIFS and of several Italian companies: CGS S.p.A, Thales-Alenia Space Italia, Rheinmetall Italia, Telespazio, Galileo Avionica, Mipot.

The satellite was lauched on April 23rd, 2007, from the Indian base of Sriharikota. AGILE raw data are down-linked to the ASI Malindi ground station in Kenya and transmitted first to the Telespazio Mission Control Center at Fucino, and then to the AGILE Data Center.

The AGILE Data Center (ADC), located at ASDC, is in charge of all the scientific oriented activities related to the analysis and archiving of AGILE data.

The AGILE team at ASDC is composed of:
P. Giommi: ASDC responsable and AGILE ASI Project Scientist
C. Pittori: archive scientist, coordinator of the AGILE Data Center
F. Lucarelli: archive scientist
P. Santolamazza: archive scientist
F. Verrecchia: archive scientist

ADC aknowledge the support of all the ASDC staff and infrastucture, and in particular the contribution of A. Antonelli and S. Colafrancesco. ADC aknowledge also the specialist informatic support of G. Fanari, R. Primavera and S. Stellato (Telespazio) and of the late Francesca Tamburelli, who was one of the main architects behind the BeppoSAX, Swift and AGILE data systems.

See also (in Italian): ASI news, INAF news, INFN news, Interview with AGILE PI Marco Tavani.

Credits: ASDC. Image background: Chandra X-ray ToO data on September 28, 2010

January 5, 2012

GRB 111211A: a new Gamma-ray Burst associated to a Supernova discovered by SuperAGILE
On 11 December 2011 at 22:17:33 UT the SuperAGILE hard X-ray monitor aboard the Italian AGILE satellite localized a Gamma Ray Burst, GRB 111211A (GCN #12666, F. Lazzarotto et al.). The GRB 111211A is the first event discovered by SuperAGILE and associated to a Supernova (GCN #12802, Ugarte Postigo et al.).

While an average number of about 200 - 300 GRBs are localised each year in the X-ray band, less than twenty firm associations with Supernovae are established up to now. The SuperAGILE GRB 111211A is a rare occurrence of a burst which appears to be accompanied by a Supernova explosion, and gives us the opportunity to investigate further the GRB-Supernova connection.

The light-curve of the GRB 111211A prompt emission is composed of two peaks: the first one is hard and also triggered the AGILE Minicalorimeter (MCAL) between 0.3 and 1.4 MeV energy, while the second one is soft and is not detected by CAL above 0.3 MeV, indicating an evident spectral evolution. The AGILE gamma-ray imager (GRID) did not detect a gamma-ray emission from this event above 50 MeV energy. The burst prompt emission has a remarkable time-integrated fluence, 9.2 x 10-6erg/cm2, as measured in the 20 - 1200 keV energy range by the Konus-Wind instrument (GCN #12676, S. Golenetskii et al.).

A Target of Opportunity observation by the Swift satellite was performed, and the afterglow was rapidly localised in X-rays (GCN #12673) and in optical-UV (GCN #12678) at a position within the SuperAGILE error region.

In the follow-up campaign the redshift of GRB 111211A was measured at z=0.478 with the X-shooter spectrograph mounted on the ESO-VLT telescope (GCN #12677). Telescopes as GROND (GCN #12668), NOT (GCN #12675) and Mt. Terskol (GCN #12704) were involved in the follow-up campaign to study the decay law of the afterglow.

On 1 January 2012, about 20 days after the SuperAGILE detection, the optical afterglow was still at a magnitude of r ~ 22.6, as observed by the GTC telescope at the Roque de los Muchachos Observatory (La Palma, Spain). The almost flat evolution at late-time of the lightcurve of the optical afterglow indicates a possible Supernova component contribution (GCN #12802). In the same observation, the spectrum of the afterglow shows characteristic signatures of a Supernova, similar to the spectrum of the type Ic SN 2006aj / GRB 060218 close to the maximum.

GRBs can be classified depending on their duration and on the boundary between short and long events is fixed at 2 s. A fairly low number of long GRBs are associated with core-collapse Supernovae, whose emission starts to show up in the lightcurve of the optical afterglow few weeks after the prompt emission. The first of these associations was discovered in 1998 by the Italian satellite BeppoSAX, between GRB 980425 and SN 1998bw.

Characteristic of the Supernovae associated to GRBs is the highly relativistic speed of their ejecta. The explanation of the so called "GRB Supernova connection" involves the explosion of massive and highly rotating stars that have lost their hydrogen envelope. The relationship, however, is not yet fully understood since there are some nearby long GRBs for which the association with a Supernova has not been found.

GRBs associated to Supernovae are generally concentrated at low redshift (that is at small distance from us), while GRB 111211A is in the higher redshift tail of the distribution. The "central engine" at the origin of the GRBs emission is still unknown and the possible correlation with other types of cosmic explosions, for example Supernovae, can give new information to understand these fascinating and still enigmatic transients.

Lightcurve of the SuperAGILE GRB 111211A

November 24, 2011

AGILE sheds light on the mistery of the origin of comic rays
AGILE has discovered a pattern of gamma-ray emission from the supernova remnant W44 that, combined with the observed multifrequency properties of the source, can be unambiguously attributed to accelerated protons interacting with nearby dense gas.

The AGILE gamma-ray imager reaches its optimal sensitivity just at the energies in the 50 MeV-a few GeV range at which neutral pions (produced by proton-proton interactions) radiate with an unambiguous signature.

The AGILE data resolves the problem of clearly identifying a source of energetic cosmic rays in our Galaxy exactly 100 years after the discovery of cosmic rays by Victor Hess in 1912. Up to now a direct identification of sites in our Galaxy where proton acceleration takes place was elusive. This important AGILE result is reported in a paper to be published by Astrophysical Journal Letters (A. Giuliani et al., 2011).

All the scientific oriented activities related to the analysis, archiving and distribution of AGILE data are supported by the AGILE Data Center at ASDC.

Figure credits: AGILE Team, G. Castelletti, G. Dubner

April 19, 2011

New Crab Nebula enhanced activity and unprecedented giant flare in gamma-rays
A renewed increase of the gamma-ray activity above 100 MeV from the Crab Nebula has been recently reported by Fermi in ATel #3276 (R. Buheler at al.) in the period April 9-11, 2011, and confirmed by the AGILE monitoring in ATel #3282 (M. Tavani et al.).

We recall that a gamma-ray flux increase from the direction of the Crab Nebula was reported for the first time by AGILE, and then confirmed by Fermi in September 2010 (ATel #2855 and ATel #2861).

Fermi satellite began a pointed mode observation of the Crab Nebula in response to the recent observed increase in gamma-ray activity.

A ToO Swift/XRT observation was also promptly performed but no significant X-ray flux variation was detected, as reported in ATel #3279 (G. Cusumano et al.).

Chandra was observing the Crab on April 12 and 13, 2011 as part of their monitoring program, which began following the previous surprising gamma-ray flare in September 2010. Chandra observations are reported in ATel #3283 (A. Tennant et al.).

A very strong gamma-ray flare was then detected by AGILE on April 16, 2011, see ATel #3286 (E. Striani et al.). The flux above 100 MeV reached the unprecedented value of F = (20.0 ± 3.7) 10^{-6} ph/cm2/sec. The detected gamma-ray flux from the Crab was then twice as bright as the Vela Pulsar.

Credits: Image background X-ray: NASA/CXC/ASU/J.Hester et al.; Optical: NASA/HST/ASU/J.Hester et al., AGILE (ASI) and Fermi (NASA) satellites.

October 7, 2010

The Crab "goes wild" in gamma-rays
More suprises from sky observations in gamma-rays.
The ASI satellite AGILE, thanks to its sky monitoring capability and fast ground segment alert system, has discovered an increased gamma-ray flux above 100 MeV from a source positionally consistent with the Crab Nebula.

The unexpected discovery has been promptly reported on September 23, 2010 in ATel #2855 (M. Tavani et al.), and confirmed the next day by the Fermi satellite in ATel #2861 (R. Buehler et al.). Fermi interrupted its all-sky scanning mode and completed a dedicated pointed observation of the Crab Nebula from 2010-09-23 to 2010-09-27 to increase its exposure on the source. Measurements taken starting on 23 September show that the gamma-ray flux is back to normal values, see ATel #2879.

The Crab Pulsar and Nebula are the remnants of the explosion of the supernova SN1054, and the spectra containing the diffuse and pulsed emission has always been considered the standard X-ray candle for X-ray and gamma-ray satellites used also for instrument calibration.

Following the surprising discovery by AGILE, the results of INTEGRAL observations of the Crab nebula, performed for calibration purpose, and the Swift/BAT team routine monitor of the source were reported in ATel #2856 and ATel #2858 respectively. In these hard X-rays observations, however, no statistically significant increase in the Crab flux was observed.

Special ToO observations were then requested and performed by Swift, see ATel #2866, Chandra, see ATel #2882, and Hubble Space Telescope, see ATel #2903. Comparing the current Crab Nebula image with the extensive database available in the HST public archive, an increased emission about 3 arcsec East of the pulsar was noticed. The Chandra exposure, taken a few days before the HST one, reported a brightening from the same region.

Gamma-ray data suggests that the origin of the flare is related to the nebula rather than the pulsar emission, and provide evidence for particle acceleration mechanisms in nebular shock regions more efficient than previously expected from current theoretical models.

In the image background: Chandra X-ray Observatory data from the ToO observation of Crab on September 28, 2010, following the gamma-ray flare detected by AGILE.

July 26, 2010

AGILE-GRID detects its brightest Gamma-Ray Burst
On July 24, 2010 AGILE detected the long bright GRB100724B (Bhat et al., GCN #10977) with both MCAL and GRID instruments (Marisaldi et al., GCN #10994, Giuliani et al., GCN #10996).

The gamma-ray emission observed by the AGILE-GRID instrument in the energy range 25 - 500 MeV with high statistical significance lasted about 100 seconds. Two main peaks are evident in the lightcurves of both low and medium-high energy gamma-rays, as also observed by Fermi LAT (see Tanaka et al., GCN #10978).

GRB 100724B turns out to be the brightest GRB detected by AGILE-GRID during its operations in space and one of the brightest ever detected above ~25 MeV.

February 15, 2010

The AGILE satellite detects "super-energetic TGFs" that could affect air travel
"Terrestrial Gamma-Ray Flashes" (TGF) are phenomena of terrestrial (atmospheric) origin only lasting a few milliseconds that are likely associated to very intense tropical thunderstorms. The AGILE satellites detected several of these events since its first months of operations.

The AGILE equatorial orbit, together with its advanced payload capabilities, allowed the discovery of TGFs with gamma-ray energy reaching up to 50 MeV.
Such highly energetic radiation must be produced in atmospheric conditions requiring potential differences of 100 Mega Volts or more, hundreds of times larger than that required to produce the usual terrestrial lightning.

As announced in a joint press release that can be found on the ASI and INAF websites, the AGILE Team and ASI are collaborating with ENAC (Ente Nazionale per l'Aviazione Civile) to understand the possible hazards to air traffic that these very energetic atmospheric events might cause.

THE AGILE paper "Detection of Terrestrial Gamma-Ray Flashes up to 40 MeV by the AGILE satellite" by M. Marisaldi et al. (2009), previously announced on this website on October 29th 2009, is now being published in the Journal of Geophysical research and it is accessible on-line at:

December 3, 2009

AGILE detects an extraordinary gamma-ray activity from the FSRQ 3C 454.3
New ATel issued: ATel #2326 (E. Striani et al.).
The AGILE Gamma-Ray Imaging Detector (GRID) has been detecting an extraordinary intense gamma-ray emission above 100 MeV from the flat spectrum radio quasar 3C 454.3. The AGILE quick-look analysis yields a source flux of about (1800 +/- 400)e-8 ph/cm2/sec (E > 100 MeV). This flux value greatly exceeds the value reported by AGILE yesterday in ATel #2322 (E. Striani et al.), showing a rapid increase (about 80%) of the gamma-ray flux of 3C 454.3 in the last 24 hours. See ATel #2326 for further details.

November 12, 2009

AGILE science operations resumed on November 4th, 2009
On November 4, 2009 at 12:25:54 the AGILE scientific operations restarted. The instrument is operating nominally, and all detectors are on and acquiring data. The satellite is currently in a safe spinning mode, with the fixed solar panels pointing towards the Sun and the GRID instrument FOV covering a good fraction of the whole sky.
In the figure below we show a preliminary 100-orbit gamma-ray intensity map above 100 MeV in the spinning configuration.

April 21, 2009

AGILE Detection of Gamma-ray Emission from the Eta-Carinae Region
AGILE Detection of Gamma-ray Emission from the Eta-Carinae Region M. Tavani et al., ApJ 698 No 2 (2009 June 20) L142-L146

During the period 2007 July � 2009 January, AGILE detected a gamma-ray source (1AGL J1043-5931) consistent with the position of the colliding wind binary system Eta-Car.

A 2-day gamma-ray flaring episode of the source was also reported on 2008 Oct. 11-13, possibly related to a transient acceleration and radiation episode of the strongly variable shock in the system.

If 1AGL J1043-5931 is the eta-Car gamma-ray counterpart, AGILE data show the first remarkable detection of a colliding wind binary system (CWB) at hundreds of MeV energies, confirming the efficient particle acceleration and the highly non-thermal nature of the strong shock in such system.