Multiwavelength Opportunities and Challenges in the Era of Public Fermi Data

📝 Abstract

The gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers both opportunities and challenges for multiwavelength and multi-messenger studies. Gamma-ray bursts, pulsars, binary sources, flaring Active Galactic Nuclei, and Galactic transient sources are all phenomena that can best be studied with a wide variety of instruments simultaneously or contemporaneously. Identification of newly-discovered gamma-ray sources is largely a multiwavelength effort. From the gamma-ray side, a principal challenge is the latency from the time of an astrophysical event to the recognition of this event in the data. Obtaining quick and complete multiwavelength coverage of gamma-ray sources can be difficult both in terms of logistics and in terms of generating scientific interest. The Fermi LAT team continues to welcome cooperative efforts aimed at maximizing the scientific return from the mission through multiwavelength studies.

💡 Analysis

The gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers both opportunities and challenges for multiwavelength and multi-messenger studies. Gamma-ray bursts, pulsars, binary sources, flaring Active Galactic Nuclei, and Galactic transient sources are all phenomena that can best be studied with a wide variety of instruments simultaneously or contemporaneously. Identification of newly-discovered gamma-ray sources is largely a multiwavelength effort. From the gamma-ray side, a principal challenge is the latency from the time of an astrophysical event to the recognition of this event in the data. Obtaining quick and complete multiwavelength coverage of gamma-ray sources can be difficult both in terms of logistics and in terms of generating scientific interest. The Fermi LAT team continues to welcome cooperative efforts aimed at maximizing the scientific return from the mission through multiwavelength studies.

📄 Content

arXiv:0912.5320v1 [astro-ph.HE] 29 Dec 2009 2009 Fermi Symposium, Washington, D.C., Nov. 2-5 1 Multiwavelength Opportunities and Challenges in the Era of Public Fermi Data D. J. Thompson NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA on behalf of the Fermi Large Area Telescope Collaboration The gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers both opportu- nities and challenges for multiwavelength and multi-messenger studies. Gamma-ray bursts, pulsars, binary sources, flaring Active Galactic Nuclei, and Galactic transient sources are all phenomena that can best be studied with a wide variety of instruments simultaneously or contemporaneously. Identification of newly-discovered gamma-ray sources is largely a multiwavelength effort. From the gamma-ray side, a principal challenge is the latency from the time of an astrophysical event to the recognition of this event in the data. Obtaining quick and complete multiwavelength coverage of gamma-ray sources can be difficult both in terms of logistics and in terms of generating scientific interest. The Fermi LAT team continues to welcome cooperative efforts aimed at maximizing the scientific return from the mission through multiwavelength studies. I. OPPORTUNITIES During its first year, the Fermi Large Area Tele- scope has excelled in producing scientific results using multiwavelength approaches. Some examples include: • PSR J1741-2054 is a radio pulsar found based on gamma-ray timing [1]. A bright Fermi LAT point source was the first step. An analysis of the LAT timing discovered gamma-ray pulsa- tions. A follow-up observation with the Swift X-Ray Telescope (XRT) found an X-ray source that gave better position information than could be determined from the LAT image. Using the LAT timing information and the Swift location allowed archival analysis using Parkes radio data and a deep search using the Green Bank Tele- scope that found the radio pulsar. • PMN J0948+0022 is known as a narrow-line quasar or a radio-loud Narrow-Line Seyfert 1 galaxy, a somewhat different class than the blazars that are regularly seen in gamma rays. Contemporaneous observations combining the LAT data with Swift (X-ray, UV, and optical) and Effelsberg (radio) revealed a Spectral En- ergy Distribution that showed this source to be similar to a blazar, indicating the presence of a relativistic jet [3]. • Using the public light curves made available by the LAT team (at the Fermi Science Support Center Web site http://fermi.gsfc.nasa.gov/ssc/) , Bon- ning et al. [2] studied simultaneous multiwave- length variability of blazar 3C454.3 using Small and Moderate Aperture Research Telescope System (SMARTS) telescopes for optical and ultraviolet and X-ray data from the Swift satellite. They found excellent correlation, with a time lag less than a day, an important parameter for modeling this blazar in terms of an external Compton model. These few examples illustrate some of the ways Fermi results enhance scientific understanding when combined with observations and analysis from other wavelengths. Because the position uncertainties for gamma-ray sources are still large compared to those at many other wavelengths, unidentified gamma-ray sources are inherently subjects for multiwavelength studies, depending on timing, spectral, and modeling to determine what objects produce the gamma rays. II. ENABLING TECHNOLOGIES Multiwavelength opportunities like those described in the previous section were not possible even a few years ago. Several developments have facilitated such multiwavelength efforts: • Communication - The ubiquity of network con- nectivity has allowed rapid exchange of data and ideas. Wireless Internet access and portable de- vices of all sorts have accelerated the exchange of information. Campaigns that once had to be organized by telephone and letter can now be arranged in a matter of minutes or hours. • Facilities - Most parts of the electromagnetic spectrum (and several multi-messenger fields) are now covered by ground-based and space- based observatories. Fermi is just one of many facilities that produce prompt and public results that can be used for multiwavelength study. • Consolidated Information Centers - Resources like ADS, NED, Simbad, ASDC, HEASARC, and others facilitate rapid discoveries of exist- ing coverage of sources. Scientists can now al- most instantaneously review archival results for nearly any cataloged object. eConf C091122 2 2009 Fermi Symposium, Washington, D.C., Nov. 2-5 III. CHALLENGES Despite the tools and resources now available for multiwavelength studies, the Fermi LAT presents some challenges in terms of making the best scien- tific use of the gamma-ray data. Three of these issues are described in the sections below. A. Challenge 1:Time-Criticality of Response Gamma-ray bursts (GRB), thanks to the the Gamma-ray bursts Coordinates Network (GCN) http://gcn.gsfc.nasa.gov/ , offer a paradigm for rapid response to transient astrophysical events. The

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