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237 May 02, 2016

The BeppoSAX X-Ray Astronomy Satellite (1996-2016): 20 years after the launch

The X-ray astronomy satellite BeppoSAX (Satellite per Astronomia X, "Beppo" in honor of Giuseppe Occhialini), is a project of the Italian Space Agency (ASI) with participation of the Netherlands Agency for Aerospace Programs (NIVR).

BeppoSAX was launched On 30 April 1996 and operated succesfully until 2002.

The main scientific characteristic of the BeppoSAX mission is the wide spectral coverage, ranging from 0.1 to over 200 keV, it was the first Italian satellite for the study of Astronomy High Energy.

In six years of operational life it has made 30.720 contacts with the Malindi ground station and has operated about 1.500 observations of different types of cosmic sources.

The most important result of the BeppoSAX Observatory was the discovery of the existence of the X-ray afterglows following Gamma Ray Burst (GRB) explosion. This major discovery earned Enrico Costa and other members of the BeppoSAX team several international recognitions including the "Enrico Fermi Award" 2010 (assigned to Enrico Costa and Filippo Frontera), the Descartes Prize of the European Union 2002 (shared among a group of scientists including Filippo Frontera, Enrico Costa, Luigi Piro and other members of the BeppoSAX team) and the Bruno Rossi Prize from the High Energy Astrophysics Division of the American Astronomical Society (awarded in 1998 to the BeppoSAX team and Jan van Paradijs).

The Archives of BeppoSAX data is available at the Center Scientific Data Italian Space Agency, ASI Science Data Center (ASDC), the multi-mission center founded in 2000 as an evolution of BeppoSAX SDC.

The BeppoSAX mission has inaugurated a new era for the High Energy Astrophysics, a field in which Italians have a long tradition of excellence.

For More details on BeppoSAX see:

The_BeppoSAX_Xray_Astronomy_satellite.pdf
The_BeppoSAX_publications_list.pdf

To commemorate this historic mission, the Italian Space Agency (ASI) organized on May 2, 2016 the event:

From the launch of Beppo-SAX today: twenty years of Italian successes in Space

237 Apr 06, 2016

An improved version of the ASDC 'Multi-Mission Interactive Archive for Space Science' tool is online!

The 'Multi-Mission Interactive Archive for Space Science' (MMIA2.0) is a new tool of the ASI Science Data Centre to explore its whole database. The ASDC is a repository of datasets from several space missions, exploring the Earth atmosphere, the Solar System and the Universe throughout the entire electromagnetic spectrum and other channels, such as the cosmic rays. MMIA2.0 is a user-friendly interface which allows scientists to access this all-encompassing and diverse databases. The tool has four main access tabs corresponding to the scientific topics supported at ASDC:

- Astrophysics and Cosmology. It groups all ASDC missions for the observation of the Universe. They are ordered according to the wavelengths/energies of their instruments, from Radio to Gamma-rays. Missions are selectable individually, in wavelength groups or in a specific spectral range. Observations of a single source or a sky region around a coordinate pairs can be retrieved (the default search radius is different for each selected mission).

- Exploration of the Solar System. This section provides links to the MATISSE tool by choosing the mission and the target. Once the user is on the MATISSE homepage the search can be performed by means of geographical (e.g. latitude/longitude) and geometrical (angle of observations) metadata to obtain both single- or multi-observation visualization.

- Particle Astrophysics/Cosmic Rays. It includes data from the only two magnetic spectrometers dedicated to charged cosmic rays research in space: PAMELA and AMS-02. Other experiments data will be added in the near future. Measurements of differential energy fluxes, time flux variations and solar flares, as well as fluxes of trapped particles in the Earth magnetosphere, and flux ratios are available in the database. The user can plot the data, download tables and graphs.

- Earth's Atmosphere/Terrestrial Gamma-ray Flashes. This is the newest ASDC tab. It currently gives access to data from Terrestrial Gamma-ray Flashes detected by the Minicalorimeter (MCAL) instrument on-board the AGILE satellite, and to light curves for the two TGF catalogs so far published by the AGILE Collaboration. Correlations with lightning and other Earth atmospheric parameters, and data from other missions will be included in MMIA2.0 in the near future.

The tool can be accessed from the ASDC main web page at www.asdc.asi or directly at www.asdc.asi.it/mma.html



237 Nov 20, 2015

Multiwavelength evidence for quasi-periodic modulation in the gamma-ray blazar PG 1553+113

Italian scientists using about 7 years of data from NASA's Fermi Gamma-ray Large Area Telescope (LAT) have detected the first evidence of quasi-periodic changes in the gamma-ray flux emitted by the BL Lac object PG 1553+113. PG 1553+113 lies in the direction of the constellation Serpens Caput, with a redshift lying between 0.395 and 0.6. This optical/X-ray-selected blazar is intensively observed from Cherenkov telescopes at very-high energy gamma rays and may have associated PeV neutrino emission, potentially increasing the interest for this result.

If confirmed in the next years, the discovery would mark the first years-long cyclic gamma-ray and correlated multifrequency emission ever detected from any AGN, providing new insights into physical processes near the central supermassive black hole.

This research is led by S. Ciprini and S. Cutini two INFN researchers belonging the Fermi team at the ASI Science Data Center (ASDC) in strict cooperation with A. Stamerra, INAF Senior Scientist at ASDC. The work has seen also a synergetic international collaboration with scientists like S. Larsson (Royal Institute of Technology, Stockholm Sweden), R. Corbet (NASA Goddard Space Flight Center, USA), both periodical visitors and collaborators of the ASDC, D. Thompson (NASA Goddard Space Flight Center, USA and Deputy Project Scientist of the Fermi mission), W. Max-Moerbeck (National Radio Astronomy Observatory, Socorro, USA) and M. Perri (INAF Rome and ASDC).

Motivated by the possibility of regular gamma-ray changes, the researchers examined a decade of multiwavelength data. These included long-term optical observations from Tuorla Observatory program in Finland, Lick Observatory, KAIT observatory in USA, and the Catalina Sky Survey near Tucson, Arizona, as well as optical and X-ray data from Swift XRT and UVOT instruments and radio, 15 GHz, data from the Owens Valley Radio Observatory, USA. Ciprini, Cutini, Stamerra and their collaborators published the findings in the Nov. 10 edition of The Astrophysical Journal Letters.

The indication of a possible 2-year periodic modulation was possible thanks to the continuous all-sky survey of Fermi; the increased capability of the new Fermi LAT Pass 8 data; and the long-term radio/optical monitoring of LAT gamma-ray blazars. If the gamma-ray cycle of PG 1553+113 is in fact real, the blazar will peak again in 2017 and 2019, well within Fermi's expected operational lifetime.

The scientists identified several scenarios that could drive periodic emission, including different mechanisms that could produce a years-long wobble in the jet of high-energy particles emanating from the black hole. For example pulsational accretion flow instabilities, jet precession, rotation and/or helical structure, or mechanisms analogous to low-frequency QPO of high-mass binary stars. The most exciting scenario involves the presence of a second supermassive black hole closely orbiting at milliparsec scales the one producing the jet we observe. The gravitational pull of the neighboring black hole would periodically tilt the inner part of its companion's accretion disk, where gas falling toward the black hole accumulates and heats up. The result would be a slow oscillation of the jet much like that of a lawn sprinkler, which could produce the cyclic gamma-ray changes we observe.

In this rather less probable but exciting scenario very-low frequency gravitational wave emission would make PG 1553+113 an ideal multimessenger high-energy-photon/neutrino/gravitational-waves source, in this sense the blazars could represent the major "cost-free" accelerators in the nature and ideal multifrequency and multimessenger physics laboratories.


Fermi observations suggest possible years-long cyclic changes in gamma-ray emission from the blazar PG 1553+113.
The marginal significance of the 2.18+/-0.08 year period gamma-ray cycle is strengthened by correlated oscillations observed in radio and optical fluxes.
The first, top panel, shows Fermi Large Area Telescope data from August 2008 to July 2015 for gamma rays with energies above 100 million electron volts (MeV) with one possible explanation for the gamma-ray cycle, an oscillation of the jet produced by the gravitational pull of a second massive black hole, seen at top left in background in this artist's rendering [credits: NASA's Goddard Space Flight Center/CI Lab].
The panels following below the pictorial artist's rendering show all the data used in this research. From top to bottom the gamma-ray (E>100 MeV, and at E>1 GeV) flux light curves (the second, third and fourth panel), the X-ray (0.3-2.0 keV) integral flux by Swift XRT, the optical flux density (R filter) from Tuorla, Catalina CSS and KAIT monitoring programs and Swift UVOT, where the dotted line is the gamma-ray light curve scaled and superposed, and the 15 GHz flux density from the OVRO 40 m radio telescope and by VLBA (the fifth, sixth and seventh panel).


237 Oct 28, 2015

Swift catches its 1000th Gamma-ray Burst!

Swift 1000th gamma-ray burst (GRB), detected on October 27 2015, has triggered the usual flurry of mail announcements by optical and radio observers who hurried to their instruments to search for the afterglow of the high-energy event. The event is named GRB 151027B to reflect the date of the detection.

Gamma-ray bursts are the most energetic explosions in the universe.
The typically last about a minute and are located randomly across the sky. GRB 151027B had a duration of about 50 seconds. They are flashes of gamma rays produced when black holes are formed and are often referred to as the birth cries of black holes.

GRBs are classified according to the duration of the event: long ones (which account for roughly 90% of the detections) last for more than 2 seconds, short ones can be over in few milliseconds. More than half of the SWIFT GRBs have been seen at optical wavelengths and 60% of such detections yielded a redshift measurement making it possible to gauge precisely the distance of the events.

After more than 10 years of operations, 1000 GRBs and 6300 Target of Opportunity observations, Swift is expanding its grasp by providing coverage for gravitation wave alerts as well as for neutrino events.

Swift, launched in November 2004, is a NASA mission with international participation from the United States, the United Kingdom, and Italy. The Italian participation includes the provision of the Malindi ground station (ASI), the mirrors of the X-ray Telescope (INAF-OAB) and the ASI Science Data Center (ASDC) which hosts an official mirror of the Swift scientific data archive and has the responsibility of the development of the Data Reduction Software for the XRT instrument on board Swift (XRTDAS).



Positions of the first 1,000 Swift GRBs on an all-sky map of our galaxy, the Milky Way. Bursts are color coded by year, and the location of GRB 151027B is shown at lower right. An annual tally of the number of bursts Swift has detected appears below the label for each year. Background: An infrared view from the Two Micron All-Sky Survey.
[Credits: NASA's Goddard Space Flight Center and 2MASS/J. Carpenter, T. H. Jarrett, and R. Hurt]


237 Sep 17, 2015

NuSTAR 7th Data Release at ASDC

The NuSTAR 7th Data Release (DR7) is available from September 17, 2015 at ASDC. The NuSTAR DR7 constitutes the final primary mission data release and contains a total of 1750 data sets.

All the NuSTAR public data at ASDC are fully integrated in the ASDC Multi-Mission Interactive Archive (MMIA). Through the MMIA the user can perform on-line analysis of all NuSTAR public observations, without the need to download any software, including the extraction of high-level scientific products (cleaned event files, sky images, energy spectra, light-curves, ARFs and RMFs).

For more details on NuSTAR, see:
http://nustar.asdc.asi.it/
http://www.nustar.caltech.edu/
http://heasarc.gsfc.nasa.gov/docs/nustar/

237 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.

237 May 12, 2015

Asymmetric explosion of SN1987A from 44Ti emission lines revealed with NuSTAR

The NASA's high-energy X-ray observatory Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the supernova 1987A (SN1987A) allowed to resolve the 67.87 and 78.32 kiloelectron volt emission lines from decay of 44Ti produced in the supernova explosion. NuSTAR data showed that these two lines are narrow and redshifted with a Doppler velocity of ~700 kilometers per second, probing direct evidence of large-scale asymmetry in the explosion.

"Stars are spherical objects, but apparently the process by which they die causes their cores to be turbulent, boiling and sloshing around in the seconds before their demise," said Steve Boggs of the University of California, Berkeley, lead author of a new study on the findings, appearing in the May 8 issue of Science. "We are learning that this sloshing leads to asymmetrical explosions."

"Titanium is produced in the very heart of the explosion, so it traces the shape of the engine driving the disassembly of the star," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology in Pasadena. "By looking at the shift of the energy of the X-rays coming from titanium, the NuSTAR data revealed that, surprisingly, most of the material is moving away from us."

Last year, NuSTAR created detailed 44Ti maps of another supernova remnant, called Cassiopeia A, also finding evidence of an asymmetrical explosion, though not to as great an extent as in 1987A. Together, these results suggest that lopsidedness is at the very root of core-collapse supernova.

NuSTAR brought a new tool to the study of supernovae. Thanks to the observatory's sharp high-energy X-ray vision, it has made the most precise measurements of 44Ti yet. This radioactive material is produced at the core of a supernova, so it provides astronomers with a direct probe into the mechanisms of a detonating star.

The Italian participation to NuSTAR includes the provision of the Malindi ground station (ASI), the ASI Science Data Center (ASDC), which contributes with the development of the NuSTARDAS software package and hosting an official mirror of the NuSTAR scientific public data archive, and a team of scientists of the Istituto Nazionale di Astrofisica (INAF) that actively collaborates on the primary scientific mission goals.

The NuSTAR team at ASDC is composed by M. Perri (INAF archive scientist), S. Puccetti (INAF archive scientist) and P. Giommi (ASDC Responsible).

For more details on NuSTAR, see:
http://nustar.asdc.asi.it
http://www.nustar.caltech.edu



Right: 59-80 keV NuSTAR spectrum of SN1987A with detected 44Ti emission lines. The observations indicate that supernovae belonging to a class called Type II or core-collapse blast apart in a lopsided fashion, with the core of the star hurtling in one direction, and the ejected material mostly expanding the other way (see model diagram at left).
[Credit: NASA/JPL-Caltech/UC Berkeley]