- ID:
- ivo://CDS.VizieR/J/ApJS/218/23
- Title:
- Fermi LAT third source catalog (3FGL)
- Short Name:
- J/ApJS/218/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100MeV-300GeV range. Based on the first 4yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse {gamma}-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources above 4{sigma} significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is ~3% at 1GeV.
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- ID:
- ivo://nasa.heasarc/fermi3fgl
- Title:
- Fermi LAT 4-Year Point Source Catalog
- Short Name:
- FERMI3FGL
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Fermi LAT 4-Year Point Source Catalog (3FGL) is a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi) mission during the first 48 months of the science phase of the mission, which began on 2008 August 4. Compared to the 2FGL catalog, the 3FGL catalog incorporates twice as much data as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse gamma-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. Sources were detected and characterized in the 100 MeV to 300 GeV range. Source detection was based on a threshold likelihood Test Statistic of 25, corresponding to a significance of just over 4 sigma. This catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits with three different spectral forms; power-law for most sources, log-parabola for significantly curved sources, and power-law with exponential cutoff for known gamma-ray pulsars. It also includes flux measurements in 5 bands for each source. The Fermi LAT Team has evaluated the populations of gamma-ray sources that are represented in the catalog using a protocol defined before launch. Individual LAT-detected sources have been provided identifications or plausible associations with sources in other astronomical catalogs. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, and a number of sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having positions that are strongly dependent on the model or as potentially entirely due to incorrectly modeled structure in the Galactic diffuse emission. This catalog has been superseded by the <a href="fermilpsc.html">Fermi LAT 8-Year Point Source Catalog</a>, also known as 4FGL. Please refer to that if you want the latest version. This database table was originally ingested by the HEASARC in May, 2015, as FERMILPSC. With the release of the 4FGL catalog in March, 2019, this catalog was renamed FERMI3FGL. The electronic data for this catalog was obtained from the Fermi Science Support Center (FSSC) at <a href="http://fermi.gsfc.nasa.gov/ssc/data/access/lat/4yr_catalog/">http://fermi.gsfc.nasa.gov/ssc/data/access/lat/4yr_catalog/</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/fermilpsc
- Title:
- Fermi LAT 14-Year Point Source Catalog (4FGL-DR4)
- Short Name:
- FERMILPSC
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Fermi Point Source Catalog (4FGL) is a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. The 14-year catalog is an incremental version (4FGL-DR4, for Data Release 4) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first fourteen years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods as the 4FGL- DR3 catalog did for 12 years of data. The spectral parameters, spectral energy distributions, light curves and associations are updated for all sources. This database table was last updated by the HEASARC in February 2024, using the latest electronic data obtained from the Fermi Science Support Center (FSSC) available at <a href="http://fermi.gsfc.nasa.gov/ssc/data/access/lat/14yr_catalog/">http://fermi.gsfc.nasa.gov/ssc/data/access/lat/14yr_catalog/</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/4193
- Title:
- Fermi/non-Fermi blazars jet power and accretion
- Short Name:
- J/MNRAS/451/4193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the relationship between jet power and accretion for Fermi and non-Fermi blazars. We also compare the relevant parameter. Our main results are: (i) Fermi and non-Fermi blazars have significant differences in red shift, black hole mass and broad line luminosity. (ii) Fermi blazars have a higher average core-dominance parameter than non-Fermi blazars, which suggests that Fermi blazars have a strong beaming effect. (iii) We find a significant correlation between broad line emission and jet power for Fermi and non-Fermi blazars, which suggests a direct tight connection between jet and accretion. (iv) The accretion and black hole mass may have a different contribution to jet power for Fermi and non-Fermi blazars.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A72
- Title:
- Fermi sources with massive YSO associations
- Short Name:
- J/A+A/530/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive protostars have associated bipolar outflows that can produce strong shocks when they interact with the surrounding medium. At these shocks, particles can be accelerated up to relativistic energies. Relativistic electrons and protons can then produce gamma-ray emission, as some theoretical models predict. To identify young galactic objects that may emit gamma rays, we crossed the Fermi First Year Catalog with some catalogs of known massive young stellar objects (MYSOs), early type stars, and OB associations, and we implemented Monte Carlo simulations to find the probability of chance coincidences. We obtained a list of massive MYSOs that are spatially coincident with Fermi sources.
- ID:
- ivo://CDS.VizieR/IX/60
- Title:
- Fermi superluminal sources
- Short Name:
- IX/60
- Date:
- 07 Mar 2022 07:19:31
- Publisher:
- CDS
- Description:
- Paper I (2019SCPMA..62l9811X): Active galactic nuclei (AGNs) have been attracting research attention due to their special observable properties. Specifically, a majority of AGNs are detected by Fermi-LAT missions, but not by Fermi-LAT, which raises the question of weather any differences exist between the two. To answer this issue, we compile a sample of 291 superluminal AGNs (189 FDSs and 102 non-FDSs) from available multi-wavelength radio, optical, and X-ray (or even {gamma}-ray) data and Doppler factors and proper motion ({mu}) (or apparent velocity ({beta}app)); calculated the apparent velocity from their proper motion, Lorentz factor ({GAMMA}), viewing angle ({phi}) and co-moving viewing angle ({phi}co) for the sources with available Doppler factor ({delta}); and performed some statistical analyses for both types. Our study indicated that (1) in terms of average values, FDSs have higher proper motions ({mu}), apparent velocities ({beta}_app_), Doppler factor ({delta}), Lorentz factor ({GAMMA}), and smaller viewing angle ({phi}). Nevertheless, there is no clear difference in co-moving viewing angles ({phi}_co_). The results reveal that FDSs show stronger beaming effect than non-FDSs. (2) In terms of correlations: 1) both sources show positive, mutually correlated fluxes, which become closer in de-beamed fluxes; 2) with respect to apparent velocities and {gamma}-ray luminosity, there is a tendency for the brighter sources to have higher velocities; 3) with regard to viewing angle and observed {gamma}-ray luminosity, log{phi}=-(0.23+/-0.04)logL{gamma}+(11.14+/-1.93), while for the co-moving viewing angle and the intrinsic {gamma}-ray luminosity, log{phi}_co_=(0.09+/-0.01)logL^in^_(gamma)_-(1.73+/-0.48). These correlations show that the luminous {gamma}-ray sources have smaller viewing angles and a larger co-moving viewing angle, which indicate a stronger beaming effect in {gamma}-ray emissions. Paper II (2020AN....341..462X): In our previous work in Xiao et al. (SCPMA, 2019, 62, 129811), we suggested that six superluminal sources could be {gamma}-ray candidates, and in fact, five of them have been confirmed in the fourth Fermi-LAT source catalog (4FGL). In this work, based on the 4FGL, we report a sample of 229 Fermi detected superluminal sources (FDSs), including 40 new FDSs and 62 non-FDSs. Thus, we believe that all superluminal sources should have {gamma}-ray emissions, and superluminal motion could also be a clue to detect {gamma}-ray emission from active galactic nuclei. We present a new approach of Doppler factor estimate through the study of the {gamma}-ray luminosity (L{gamma}) and of the viewing angle ({phi}). Paper III (2020A&C....3200387X): In this work, Machine Learning (ML) methods are used to efficiently identify the unassociated sources and the Blazar Candidate of Uncertain types (BCUs) in the Fermi-LAT Third Source Catalog (3FGL). The aims are twofold: (1) to distinguish the Active Galactic Nuclei (AGNs) from others (non-AGNs) in the unassociated sources; (2) to identify BCUs into BL Lacertae objects (BL Lacs) or Flat Spectrum Radio Quasars (FSRQs). Two dimensional reduction methods are presented to decrease computational complexity, where Random Forest (RF), Multilayer Perceptron (MLP) and Generative Adversarial Nets (GAN) are trained as individual models. In order to achieve better performance, the ensemble technique is further explored. It is also demonstrated that grid search method is of help to choose the hyperparameters of models and decide the final predictor, by which we have identified 748 AGNs out of 1010 unassociated sources, with an accuracy of 97.04%. Within the 573 BCUs, 326 have been identified as BL Lacs and 247 as FSRQs, with an accuracy of 92.13%.
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/1294
- Title:
- Fermi unassociated sources ATCA observations
- Short Name:
- J/MNRAS/432/1294
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results of the first phase of observations with Australia Telescope Compact Array (ATCA) at 5 and 9GHz of the fields around 411 {gamma}-ray sources with declinations less than +10{deg} detected with Fermi but marked as unassociated in the 2FGL catalogue. We have detected 424 sources with flux densities in a range of 2mJy to 6Jy in the fields of 283 {gamma}-ray sources within their position error ellipses drawn to cover the area of 99 per cent probability of their localisation. Of them, 146 objects were detected in both bands. We found 84 sources with spectral index flatter than -0.5 in our sample. The majority of detected sources are weaker than 100 mJy and for this reason were not found in previous surveys. Approximately 1/3 of our sample, 128 objects, have the probability of being associated by more than 10 times than the probability of being a background source found in the vicinity of a {gamma}-ray object by chance. We present the catalogue of positions of these sources, estimates of their flux densities and spectral indices when available.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A74
- Title:
- FeSt 1-457 IRAM and PdBI maps
- Short Name:
- J/A+A/597/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pre-stellar cores within molecular clouds provide the very initial conditions in which stars are formed. FeSt 1-457 is a prototypical starless core and the most chemically evolved among those isolated, embedded in the most pristine part of the Pipe nebula, the bowl. We use the IRAM 30m telescope and the PdBI to study the chemical and physical properties of the starless core FeSt 1-457 (Core 109) in the Pipe nebula. We fit the hyperfine structure of the N_2_H^+^ (1-0) IRAM 30m data. This allowed us to measure with high precision the velocity field, line widths and opacity and derive the excitation temperature and column density in the core. We used a modified Bonnor-Ebert sphere model adding a temperature gradient towards the center to fit the 1.2mm continuum emission and visual extinction maps. Using this model, we have estimated the abundances of the N_2_H^+^ and the rest of molecular lines detected in the 30GHz wide line survey performed at 3mm with IRAM 30m using ARTIST software.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A60
- Title:
- F-GAMMA 2.64-43GHz radio data over 2007-2015
- Short Name:
- J/A+A/626/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The advent of the Fermi gamma-ray space telescope with its superb sensitivity, energy range, and unprecedented capability to monitor the entire 4{pi} sky within less than 2-3 h, introduced a new standard in time domain gamma-ray astronomy. Among several breakthroughs, Fermi has - for the first time - made it possible to investigate, with high cadence, the variability of the broadband spectral energy distribution (SED), especially for active galactic nuclei (AGN). This is necessary for understanding the emission and variability mechanisms in such systems. To explore this new avenue of extragalactic physics the Fermi-GST AGN Multi-frequency Monitoring Alliance (F-GAMMA) programme undertook the task of conducting nearly monthly, broadband radio monitoring of selected blazars, which is the dominant population of the extragalactic gamma-ray sky, from January 2007 to January 2015. In this work we release all the multi-frequency light curves from 2.64 to 43 GHz and first order derivative data products after all necessary post-measurement corrections and quality checks. Along with the demanding task to provide the radio part of the broadband SED in monthly intervals, the F-GAMMA programme was also driven by a series of well-defined fundamental questions immediately relevant to blazar physics. On the basis of the monthly sampled radio SEDs, the F-GAMMA aimed at quantifying and understanding the possible multiband correlation and multi-frequency radio variability, spectral evolution and the associated emission, absorption and variability mechanisms. The location of the gamma-ray production site and the correspondence of structural evolution to radio variability have been among the fundamental aims of the programme. Finally, the programme sought to explore the characteristics and dynamics of the multi-frequency radio linear and circular polarisation. The F-GAMMA ran two main and tightly coordinated observing programmes. The Effelsberg 100 m telescope programme monitoring 2.64, 4.85, 8.35, 10.45, 14.6, 23.05, 32, and 43 GHz, and the IRAM 30 m telescope programme observing at 86.2, 142.3, and 228.9 GHz. The nominal cadence was one month for a total of roughly 60 blazars and targets of opportunity. In a less regular manner the F-GAMMA programme also ran an occasional monitoring with the APEX 12 m telescope at 345 GHz. We only present the Effelsberg dataset in this paper. The higher frequencies data are released elsewhere. The current release includes 155 sources that have been observed at least once by the F-GAMMA programme. That is, the initial sample, the revised sample after the first Fermi release, targets of opportunity, and sources observed in collaboration with a monitoring programme following up on Planck satellite observations. For all these sources we release all the quality-checked Effelsberg multi-frequency light curves. The suite of post-measurement corrections and flagging and a thorough system diagnostic study and error analysis is discussed as an assessment of the data reliability. We also release data products such as flux density moments and spectral indices. The effective cadence after the quality flagging is around one radio SED every 1.3 months. The coherence of each radio SED is around 40 min. The released dataset includes more than 3x104 measurements for some 155 sources over a broad range of frequencies from 2.64 GHz to 43 GHz obtained between 2007 and 2015. The median fractional error at the lowest frequencies (2.64-10.45 GHz) is below 2%. At the highest frequencies (14.6-43 GHz) with limiting factor of the atmospheric conditions, the errors range from 3% to 9%, respectively.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/197
- Title:
- F, G and K stars BVRI photometry
- Short Name:
- J/A+AS/131/197
- Date:
- 15 Dec 2021 08:12:40
- Publisher:
- CDS
- Description:
- We present accurate BV(RI)c photometry for a sample of F, G and K stars detected in selected areas of the ROSAT all-sky survey (RASS). We have used the photometry, in addition to low-resolution spectroscopy, to estimate spectral classifications, distances and X-ray luminosities. The log(L_X_/L_V_) in the sample lies below -2. Although the sample contains also nearby, inactive stars, it is dominated by active objects. The median X-ray luminosity in our sample is <L_X_>=29.88 and the mean value of the hardness ratios <HR1>=0.13+/-0.35. We compare the derived X-ray luminosity function with similar functions obtained from the serendipitous samples of the Einstein Observatory medium sensitivity survey (EMSS, Cat. <IX/15>) and EXOSAT (Cat. <J/A+AS/115/41>). Our sample is completely consistent with the EMSS sample of solar type stars, indicating that both our sources and the EMSS sources are representative of the high galactic latitude X-ray stellar population. We do not find extremely active stars (log(L_X_)>=32), as are found in the EMSS sample, and we argue that these objects are rare.