- ID:
- ivo://CDS.VizieR/J/ApJ/826/37
- Title:
- Fermi/GBM obs. of V404 Cygni 2015 outburst
- Short Name:
- J/ApJ/826/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V404 Cygni was discovered in 1989 by the Ginga X-ray satellite during its only previously observed X-ray outburst and soon after confirmed as a black hole binary. On 2015 June 15, the Gamma-ray Burst Monitor (GBM) triggered on a new outburst of V404 Cygni. We present 13 days of GBM observations of this outburst, including Earth occultation flux measurements and spectral and temporal analysis. The Earth occultation fluxes reached 30 Crab with detected emission to 100keV and determined, via hardness ratios, that the source was in a hard state. At high luminosity, spectral analysis between 8 and 300keV showed that the electron temperature decreased with increasing luminosity. This is expected if the protons and electrons are in thermal equilibrium during an outburst with the electrons cooled by the Compton scattering of softer seed photons from the disk. However, the implied seed photon temperatures are unusually high, suggesting a contribution from another source, such as the jet. No evidence of state transitions is seen during this time period. The temporal analysis reveals power spectra that can be modeled with two or three strong, broad Lorentzians, similar to the power spectra of black hole binaries in their hard state.
Number of results to display per page
Search Results
- ID:
- ivo://nasa.heasarc/fermigsol
- Title:
- Fermi GBM Solar Flare Catalog
- Short Name:
- FERMIGSOL
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- These data represent the Fermi GBM Solar Flare Catalog. Data in this catalog are targeted specifically at Fermi observations of high-energy solar phenomena, primarily solar flares, in order to facilitate the use of Fermi data by the international solar physics community. This table catalogs Fermi Gamma-Ray Burst Monitor (GBM) triggers associated with known solar flares. The Fermi GBM Solar Flare Catalog is supported by a Fermi Guest Investigator program and maintained at <a href="http://hesperia.gsfc.nasa.gov/fermi_solar">http://hesperia.gsfc.nasa.gov/fermi_solar</a>. Please include the following acknowledgment if you use these facilities in a paper or presentation: "We acknowledge the use of the Fermi Solar Flare Observations facility funded by the Fermi GI program (<a href="http://hesperia.gsfc.nasa.gov/fermi_solar/">http://hesperia.gsfc.nasa.gov/fermi_solar/</a>)." The information in this table is provided independently by a Fermi Guest Investigator grant. The tabulated data come from <a href="http://hesperia.gsfc.nasa.gov/fermi/gbm/qlook/fermi_gbm_flare_list.txt">http://hesperia.gsfc.nasa.gov/fermi/gbm/qlook/fermi_gbm_flare_list.txt</a>. This table is updated automatically within a day or so of a new data file being made available. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/fermigtrig
- Title:
- Fermi GBM Trigger Catalog
- Short Name:
- FERMIGTRIG
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table lists all of the triggers observed by one or more of the 14 GBM detectors (12 NaI and 2 BGO). Note that there are two Browse catalogs resulting from GBM triggers. All GBM triggers are entered in the Trigger Catalog, but only those triggers classified as bursts are entered in the <a href="/W3Browse/fermi/fermigbrst.html">Fermi GBM Burst Catalog</a>. Thus, a burst will be found in both the Trigger and Burst Catalogs. The Burst Catalog analysis requires human intervention; therefore, GRBs will be entered in the Trigger Catalog before the Burst Catalog. The latency requirements are 1 day for triggers and 3 days for bursts. The GBM consists of an array of 12 sodium iodide (NaI) detectors which cover the lower end of the energy range up to 1 MeV. The GBM triggers off of the rates in the NaI detectors, with some Terrestrial Gamma-ray Flash (TGF)-specific algorithms using the bismuth germanate (BGO) detectors, sensitive to higher energies, up to 40 MeV. The NaI detectors are placed around the Fermi spacecraft with different orientations to provide the required sensitivity and FOV. The cosine-like angular response of the thin NaI detectors is used to localize burst sources by comparing rates from detectors with different viewing angles. The two BGO detectors are placed on opposite sides of the spacecraft so that all sky positions are visible to at least one BGO detector. The signals from all 14 GBM detectors are collected by a central Data Processing Unit (DPU). This unit digitizes and time-tags the detectors' pulse height signals, packages the resulting data into several different types for transmission to the ground (via the Fermi spacecraft), and performs various data processing tasks such as autonomous burst triggering. The information in this table is provided by the Fermi Gamma-ray Burst Monitor Instrument Operations Center (GIOC) and the Fermi Science Support Center (FSSC). The values come from a trigger catalog entry file or a burst catalog entry file provided by the GIOC. These are FITS files which may contain additional data in extensions for bursts (see the spectrum_flag and fit_flag columns) and are available for download. This table is updated automatically within a day or so of new data files being processed and made available. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/806/52
- Title:
- 8 Fermi GRB afterglows follow-up
- Short Name:
- J/ApJ/806/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi Gamma-ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi GRB Monitor instrument have posed a formidable obstacle to locating the bursts' host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target-of-opportunity (TOO) mode for the intermediate Palomar Transient Factory (iPTF) in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: 8 afterglow discoveries out of 35 searches. Two of the bursts with detected afterglows (GRBs 130702A and 140606B) were at low redshift (z=0.145 and 0.384, respectively) and had spectroscopically confirmed broad-line Type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samples. We identify one new outlier on the Amati relation. We find that two bursts are consistent with a mildly relativistic shock breaking out from the progenitor star rather than the ultra-relativistic internal shock mechanism that powers standard cosmological bursts. Finally, in the context of the Zwicky Transient Facility, we discuss how we will continue to expand this effort to find optical counterparts of binary neutron star mergers that may soon be detected by Advanced LIGO and Virgo.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/15
- Title:
- Fermi GRB analysis. III. T_90_ distributions
- Short Name:
- J/ApJ/763/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The durations (T_90_) of 315 gamma-ray bursts (GRBs) detected with Fermi/GBM (8-1000keV) up to 2011 September are calculated using the Bayesian Block method. We compare the T_90_ distributions between this sample and those derived from previous/current GRB missions. We show that the T_90_ distribution of this GRB sample is bimodal, with a statistical significance level comparable to those derived from the BeppoSAX/GRBM sample and the Swift/BAT sample, but lower than that derived from the CGRO/BATSE sample. The short-to-long GRB number ratio is also much lower than that derived from the BATSE sample, i.e., 1:6.5 versus 1:3. We measure T_90_ in several bands, i.e., 8-15, 15-25, 25-50, 50-100, 100-350, and 350-1000keV, to investigate the energy-dependence effect of the bimodal T_90_distribution. It is found that the bimodal feature is well observed in the 50-100 and 100-350keV bands, but is only marginally acceptable in the 25-50keV and 350-1000keV bands. The hypothesis of bimodality is confidently rejected in the 8-15 and 15-25keV bands. The T_90_distributions in these bands are roughly consistent with those observed by missions with similar energy bands. The parameter T_90_ as a function of energy follows {overline}{T}_90_{propto}E^-0.20+/-0.02^ for long GRBs. Considering the erratic X-ray and optical flares, the duration of a burst would be even longer for most GRBs. Our results, together with the observed extended emission of some short GRBs, indicate that the central engine activity timescale would be much longer than T_90_ for both long and short GRBs and the observed bimodal T_90_ distribution may be due to an instrumental selection effect.
6186. Fermi/LAT AGN at 5GHz
- ID:
- ivo://CDS.VizieR/J/ApJ/757/25
- Title:
- Fermi/LAT AGN at 5GHz
- Short Name:
- J/ApJ/757/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The parsec-scale radio properties of 232 active galactic nuclei, most of which are blazars, detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA) at 5GHz. Data from both the first 11 months (1FGL) and the first 2 years (2FGL) of the Fermi mission were used to investigate these sources' {gamma}-ray properties. We use the ratio of the {gamma}-ray-to-radio luminosity as a measure of {gamma}-ray loudness. We investigate the relationship of several radio properties to {gamma}-ray loudness and to the synchrotron peak frequency. There is a tentative correlation between {gamma}-ray loudness and synchrotron peak frequency for BL Lac objects in both 1FGL and 2FGL, and for flat-spectrum radio quasars (FSRQs) in 2FGL. We find that the apparent opening angle tentatively correlates with {gamma}-ray loudness for FSRQs, but only when we use the 2FGL data. We also find that the total VLBA flux density correlates with the synchrotron peak frequency for BL Lac objects and FSRQs. The core brightness temperature also correlates with synchrotron peak frequency, but only for the BL Lac objects. The low-synchrotron-peaked (LSP) BL Lac object sample shows indications of contamination by FSRQs which happen to have undetectable emission lines. There is evidence that the LSP BL Lac objects are more strongly beamed than the rest of the BL Lac object population.
- ID:
- ivo://CDS.VizieR/J/ApJS/183/46
- Title:
- Fermi/LAT bright gamma-ray source list (0FGL)
- Short Name:
- J/ApJS/183/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100MeV for the 205 most significant (statistical significance greater than ~10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.
- ID:
- ivo://nasa.heasarc/fermilbsl
- Title:
- Fermi LAT Bright Source List
- Short Name:
- FERMILBSL
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Fermi LAT table of bright sources is a list of bright LAT sources that have statistical significances of 10 sigma or higher, based on the first three months of survey data. The primary purpose of this list is to assist proposers for Guest Investigator Cycle 2 (due date 6 March). This list will eventually be superseded by the LAT Source Catalog, to be released about one year after launch. This database table was created by the HEASARC in February 2009 based on the electronic data obtained from the Fermi Science Support Center (FSSC) available at <a href="http://fermi.gsfc.nasa.gov/ssc/data/access/lat/bright_src_list/">http://fermi.gsfc.nasa.gov/ssc/data/access/lat/bright_src_list/</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1060
- Title:
- Fermi/LAT broad emission line blazars
- Short Name:
- J/MNRAS/448/1060
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the broad emission line blazars detected in the {gamma}-ray band by the Large Area Telescope onboard the Fermi satellite and with the optical spectrum studied by Shaw et al. (2012, Cat. J/ApJ/748/49, hereafter S12, and 2013, Cat. J/ApJ/764/135, hereafter S13). The observed broad line strength provides a measure of the ionizing luminosity of the accretion disc, while the {gamma}-luminosity is a proxy for the bolometric non-thermal beamed jet emission. The resulting sample, composed by 217 blazars, is the best suited to study the connection between accretion and jet properties. We compare the broad emission line properties of these blazars with those of radio-quiet and radio-loud quasars present in the Sloan Digital Sky Survey, to asses differences and similarities of the disc luminosity and the virial black hole mass. For most sources, we could derive the black hole mass by reproducing the IR-optical-UV data with a standard accretion disc spectrum, and we compared the black hole masses derived with the two methods. The distributions of the masses estimated in the two ways agree satisfactorily. We then apply a simple, one-zone, leptonic model to all the 217 objects of our sample. The knowledge of the black hole mass and disc luminosity helps to constrain the jet parameters. On average, they are similar to what found by previous studies of smaller samples of sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/597
- Title:
- FERMI LAT detected blazars
- Short Name:
- J/ApJ/700/597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first three months of sky-survey operation with the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope reveal 132 bright sources at |b|>10{deg} with test statistic greater than 100 (corresponding to about 10{sigma}). Two methods, based on the CGRaBS, CRATES, and BZCat catalogs, indicate high-confidence associations of 106 of these sources with known active galactic nuclei (AGNs). This sample is referred to as the LAT Bright AGN Sample (LBAS). It contains two radio galaxies, namely, Centaurus A and NGC 1275, and 104 blazars consisting of 58 flat spectrum radio quasars (FSRQs), 42 BL Lac objects, and 4 blazars with unknown classification. Four new blazars were discovered on the basis of the LAT detections. Remarkably, the LBAS includes 10 high-energy-peaked BL Lacs (HBLs), sources which were previously difficult to detect in the GeV range. Another 10 lower-confidence associations are found. Only 33 of the sources, plus two at |b|<10{deg}, were previously detected with Energetic Gamma-Ray Experiment Telescope (EGRET), probably due to variability.