Fermi Catalog Research Articles

Constraints on cosmological models with gamma-ray bursts in cosmology-independent way

In this paper, we present a cosmology-independent method to constrain cosmological models from the latest 221 gamma-ray bursts (GRBs) sample, including 49 GRBs from Fermi catalog with the Amati relation (the [Formula: see text] correlation), which are calibrated by using a Gaussian process from the Pantheon+ type Ia supernovae (SNe Ia) sample. With 182 GRBs at [Formula: see text] in the Hubble diagram and the latest observational Hubble data (OHD) by the Markov Chain Monte Carlo (MCMC) method, we obtained [Formula: see text] and [Formula: see text] for the flat [Formula: see text]CDM model and [Formula: see text], [Formula: see text], [Formula: see text] for the flat wCDM model. These results are consistent with those in which the coefficients of the Amati relation and the cosmological parameters fitted simultaneously.

Detection of new gamma-ray AGN candidates using DBSCAN and SIMEFIC III in Fermi-LAT data

Abstract We present the detection of new high-energy gamma-ray AGN candidates using the DBSCAN clustering algorithm on two-dimensional gamma-ray data from Fermi-LAT. Our approach involves iterative applications of the SIMEFIC III algorithm, designed to enhance point source detection. By integrating DBSCAN at each denoising step, we track and evaluate the significance of potential sources across iterations. Our findings indicate that source significance increases to a specific threshold, beyond which further denoising may remove genuine sources. At the optimal denoising stage, we identified 18 sources not listed in the Fermi catalog, with several of these sources potentially matching entries in the CRATES and Roma-BZCAT catalogs.

A search for AGN sources of the IceCube diffuse neutrino flux

The origin of the diffuse astrophysical neutrino flux measured by the IceCube Observatory remains largely unknown.Although NGC 1068 and TXS 0506+056 have been identified as potential neutrino sources, the diffuse flux of neutrinos must have additional sources that have not yet been identified.Here we investigate potential correlations between IceCube's neutrino events and the Fermi and MOJAVE source catalogs, using the publicly-available IceCube data set. We perform three separate spatially-dependent, energy-dependent, and time-dependent searches, and find no statistically significant sources outside of NGC 1068. We find that, under the most optimistic assumptions of a spectral index of 2.0 and a neutrino flux uncorrelated with the gamma ray flux, no more than 13% of IceCube's neutrino flux originates from blazars over the whole sky. Then, using an energy-dependent likelihood analysis, the limit on neutrinos originating from blazars reduces to 9% in the Northern hemisphere under the same spectral index and flux assumptions. Finally, we set limits on individual sources from the MOJAVE radio catalog after finding no statistically significant time-flaring sources.

4FGL J1318.2+6754: A Long Orbital-period Redback Candidate

By combining the Fermi catalog and the single-lined spectroscopic binaries of Gaia Data Release 3 (DR3), we report a new candidate redback millisecond pulsar binary, which is recommended as a target for radio telescopes to detect pulsed signals. Using TESS data in the T band spanning over 4 yr, we find a period of ∼4.13 days, which is consistent with the radial velocity solution of the Gaia DR3 and optical spectroscopy from the LAMOST telescope. The light curve in the T band reveals periodic modulation of low amplitude that is a characteristic feature of the heating of the photosphere of a nondegenerate low-mass stellar companion by the pulsar wind. The nondegenerate companion is a bright (G = 11.96), slightly metal-poor ([Fe/H] = − 0.55), G-type main-sequence star (T eff = 5891 K; R = 1.356R ⊙). This orbital period of 4.13 days would be the longest one for known redback candidates, which could hardly be understood for its formation in the standard recycling scenario due to its large Roche-lobe radius (≫the radius of the G-type main-sequence star). It is proposed here that this candidate redback millisecond pulsar binary could be created via accretion-induced collapse of an oxygen–neon–magnesium white dwarf.

Leptohadronic multi-messenger modeling of 324 gamma-ray blazars

Context. The origin of the diffuse astrophysical neutrino flux observed by the IceCube experiment is still under debate. Multiple associations have been reported between high-energy neutrino events and individual bla/ars, such as the source TXS 0506+056, which are active galaxies with relativistic jets pointing toward Earth. From a theoretical perspective, the properties of these sources as neutrino emitters are not yet well understood. Aims. By systematically modeling the effect of cosmic-ray protons on the multiwavelength data from the largest sample of bright gamma-ray bla/ars to date, we expect to learn about the multi-messenger nature of the active galaxy population as a whole, as well as the relationship between neutrino production and the multiwavelength spectrum of these sources. Methods. We predict the emitted multiwavelength and neutrino spectrum using a self-consistent numerical radiation model applied individually to each source in the sample. We then study the properties of the full population and identify empirical relations. We focus on public multiwavelength data from the radio to the gamma-ray bands from a sample of 324 bla/ars detected by the Fermi Large Area Telescope (LAT), most of which are flat-spectrum radio quasars (FSRQs). This amounts to 34% of all FSRQs in the latest Fermi catalog. Results. We demonstrate that the optical and gigaelectronvolt gamma-ray broadband features are generally well described by electron emission, which helps for the location of the emission region relative to the central black hole to be constrained. For 33% of the bla/ars in our sample, a description of the observed X-ray spectrum benefits from an additional component from proton interactions, in agreement with recent studies of individual IceCube candidate bla/ars. We show that, on average, bla/ars that are brighter in gigaelectronvolt gamma rays have a higher neutrino production efficiency but a lower best-fit baryonic loading. The predicted neutrino luminosity shows a positive correlation both with the observed flux of gigaelectronvolt gamma rays and with the predicted flux of megaelectronvolt gamma rays. We also estimate the diffuse neutrino flux from gamma-ray bla/ars by extrapolating the result to the Fermi population, and we show that it may be at the level of ~20% of the diffuse neutrino flux observed by IceCube, in agreement with current limits from stacking analyses. We discuss the implications of our results for future neutrino searches and suggest promising sources for potential detections.

Unsupervised machine learning classification of Fermi gamma-ray bursts using spectral parameters

ABSTRACT A thorough analysis of 2297 gamma-ray bursts (GRBs) in the Fermi catalogue is performed by using unsupervised machine learning algorithms in this paper. In our analysis, for two spectral parameter samples, namely for the peak-flux and time-integrated spectral fits, two dimensionality reduction algorithms, t-distributed stochastic neighbour embedding (t-SNE), and uniform manifold approximation and projection (UMAP), are used to generate four embedding maps; further, K-means algorithm is used for searching for the optimal clustering on the four maps. Our results show that Fermi GRBs can be well separated into two groups. For the time-integrated spectral parameters, both UMAP and t-SNE algorithms classify 372 bursts as short GRBs and 1925 bursts as long GRBs, and 384 bursts as short GRBs and 1913 bursts as long GRBs for the peak-time spectral parameters. This new classification method differs from traditional long and short classifications because it is not based on duration. In addition, it is found that the classification results of 11 GRBs are inconsistent between the integrated and peak-time spectral samples. GRB200826A is the first confirmed short GRB of collapsar origin, and the physical origins of these GRBs may be similar to it.

The unprecedented flaring activities around Mrk 421 in 2012 and 2013: The test for neutrino and UHECR event connection

Since its mission, Fermi Collaboration reported the highest flux observed during July - September 2012 for the BL Lac Markarian 421 (Mrk 421). The integrated flux was eight times greater than the average flux reported in the second Fermi catalog. During April 2013, Mrk 421 exhibited the highest TeV γ-ray and optical fluxes recorded. The Telescope Array (TA) collaboration reported the arrival of 72 ultra-high-energy cosmic rays (UHECRs), two in temporal and positional coincidence with the flaring activity observed in 2012 and one with the flaring activity in 2013. The IceCube collaboration has reported around 100 neutrino events in the High-Energy Starting Events (HESE) catalog. Although no neutrino track-like event has been associated with this source, a neutrino shower-like event (IC31) is in temporal and positional coincidence with the flare in 2012. Describing the broadband spectral energy distribution during the flaring activities exhibited in 2012 and 2013 with one- and two-zone lepto-hadronic scenarios and one-zone SSC model, we study a possible correlation between the neutrino event IC31 and the three UHECRs. We estimate the number of neutrino and UHECR events generated from the proposed models, and show that while the neutrino events are low to associate the event IC31 with Mrk 421, the number of UHECRs are similar to those reported by TA collaboration.

The Gamma-Ray Pulsar Phenomenology in View of 3D Kinetic Global Magnetosphere Models

We develop kinetic plasma models of pulsar magnetospheres with magnetic-field-line-dependent plasma injection that reveal the importance of various magnetosphere regions in regulating the γ-ray emission. We set different particle injection rates for the so-called open, closed, and separatrix zones. Moderate particle injection rates in open and closed zones ensure a global field structure close to the force-free structure, while the dissipation occurs mainly in and around the equatorial current sheet. The particles that are injected into the separatrix zone affect the particle populations that enter the equatorial current sheet region, and therefore the corresponding accelerating electric fields, particle energies, the spectral cutoff energy, and γ-ray efficiency. The separatrix zone models reproduce the recently discovered fundamental plane of γ-ray pulsars consistent with curvature radiation emission, the γ-ray light-curve shapes, and the radio-lag versus peak-separation correlation reported in the Fermi second pulsar catalog. The model beaming factors indicate that the pulsar total γ-ray luminosities listed in the Fermi catalogs are overestimations of the actual ones. We find that the radiation reaction limited regime starts ceasing to govern the high-energy emission for . Our results also indicate that toward high magnetic inclination angles, the Y point around the rotational equator migrates well inside the light cylinder, sparking additional peaks in the γ-ray pulse profiles. We find that an equivalent enhanced particle injection beyond the Y point strengthens these features, making the model γ-ray light curves inconsistent with those observed.

Fermi LAT AGN classification using supervised machine learning

ABSTRACT Classifying active galactic nuclei (AGNs) is a challenge, especially for BL Lacertae objects (BLLs), which are identified by their weak emission line spectra. To address the problem of classification, we use data from the fourth Fermi Catalog, Data Release 3. Missing data hinder the use of machine learning to classify AGNs. A previous paper found that Multivariate Imputation by Chain Equations (MICE) imputation is useful for estimating missing values. Since many AGNs have missing redshift and the highest energy, we use data imputation with MICE and k-nearest neighbours (kNN) algorithm to fill in these missing variables. Then, we classify AGNs into the BLLs or the flat spectrum radio quasars (FSRQs) using the SuperLearner, an ensemble method that includes several classification algorithms like logistic regression, support vector classifiers, Random Forest, Ranger Random Forest, multivariate adaptive regression spline (MARS), Bayesian regression, and extreme gradient boosting. We find that a SuperLearner model using MARS regression and Random Forest algorithms is 91.1 per cent accurate for kNN-imputed data and 91.2 per cent for MICE-imputed data. Furthermore, the kNN-imputed SuperLearner model predicts that 892 of the 1519 unclassified blazars are BLLs and 627 are FSRQs, while the MICE-imputed SuperLearner model predicts 890 BLLs and 629 FSRQs in the unclassified set. Thus, we can conclude that both imputation methods work efficiently and with high accuracy and that our methodology ushers the way for using SuperLearner as a novel classification method in the AGN community and, in general, in the astrophysics community.

A new redback pulsar candidate 4FGL J2054.2+6904

ABSTRACT The Fermi catalogue contains about 2000 unassociated γ-ray sources. Some of them were recently identified as pulsars, including so-called redbacks and black widows, which are millisecond pulsars in tight binary systems with non- and partially-degenerate low-mass stellar companions irradiated by the pulsar wind. We study a likely optical and X-ray counterpart of the Fermi source 4FGL J2054.2+6904 proposed earlier as a pulsar candidate. We use archival optical data as well as Swift/XRT and SRG/eROSITA X-ray data to clarify its nature. Using Zwicky Transient Facility data in g and r bands spanning over 4.7 yr, we find a period of ≈7.5 h. The folded light curve has a smooth sinusoidal shape with the peak-to-peak amplitude of ≈0.4 mag. The spectral fit to the optical spectral energy distribution of the counterpart candidate gives the star radius of 0.5 ± 0.1 R⊙ and temperature of 5500 ± 300 K implying a G2–G9-type star. Its X-ray spectrum is well fitted by an absorbed power law with the photon index of 1.0 ± 0.3 and unabsorbed flux of ≈2 × 10−13 erg s−1 cm−2. All the properties of 4FGL J2054.2+6904 and its presumed counterpart suggest that it is a member of the redback family.

Using Neural Networks to Differentiate Newly Discovered BL Lacertae Objects and FSRQs among the 4FGL Unassociated Sources Employing Gamma-Ray, X-Ray, UV/Optical, and IR Data

Among the ∼2157 unassociated sources in the third data release (DR3) of the fourth Fermi catalog, ∼1200 were observed with the Neil Gehrels Swift Observatory pointed instruments. These observations yielded 238 high signal-to-noise ratio X-ray sources within the 95% Fermi uncertainty regions. Recently, Kerby et al. employed neural networks to find blazar candidates among these 238 X-ray counterparts to the 4FGL unassociated sources and found 112 likely blazar counterpart sources. A complete sample of blazars, along with their subclassification, is a necessary step to help understand the puzzle of the blazar sequence and for the overall completeness of the gamma-ray emitting blazar class in the Fermi catalog. We employed a multi-perceptron neural network classifier to identify flat spectrum radio quasars (FSRQs) and BL Lac objects among these 112 blazar candidates using the gamma-ray, X-ray, UV/optical, and IR properties. This classifier provided probability estimates for each source to be associated with one or the other category, such that P fsrq represents the probability for a source to be associated with the FSRQ subclass. Using this approach, four FSRQs and 50 BL Lac objects are classified as such with >99% confidence, while the remaining 58 blazars could not be unambiguously classified as either BL Lac objects or FSRQs.

A blazar candidate for the Fermi source 4FGL J1848.7–0129

Abstract The Fermi source 4FGL J1848.7–0129 has been historically related to the globular cluster GLIMPSE-C01 since its very first detection. Although this association is widely accepted, as it appears in the most recent Fermi catalogue, it deserves to be revisited given the multiwavelength evidences and the recent discovery of variable X-ray sources in the Fermi source region. In particular, low frequency radio maps from the Giant Metre Radio Telescope in Pune (India) have been carefully inspected which, together with X-ray data re-analysis from Chandra, lead us to get a deep insight into the candidates to be associated to 4FGL J1848.7–0129. This results in the discovery of a new X-ray variable point source coincident with an unreported non-thermal radio emitter, both of them well inside the 4FGL J1848.7–0129 error ellipse. We analyse and discuss all these observational facts, and we propose now a newly discovered blazar candidate as the most promising responsible for the gamma-ray emission in the Fermi source. If confirmed, this result would set constrains on the number of millisecond pulsars in GLIMPSE-C01 or their gamma-ray emission properties.

Predicting the Redshift of Gamma-Ray Loud AGNs Using Supervised Machine Learning. II

Abstract Measuring the redshift of active galactic nuclei (AGNs) requires the use of time-consuming and expensive spectroscopic analysis. However, obtaining redshift measurements of AGNs is crucial as it can enable AGN population studies, provide insight into the star formation rate, the luminosity function, and the density rate evolution. Hence, there is a requirement for alternative redshift measurement techniques. In this project, we aim to use the Fermi Gamma-ray Space Telescope’s 4LAC Data Release 2 catalog to train a machine-learning (ML) model capable of predicting the redshift reliably. In addition, this project aims at improving and extending with the new 4LAC Catalog the predictive capabilities of the ML methodology published in Dainotti et al. Furthermore, we implement feature engineering to expand the parameter space and a bias correction technique to our final results. This study uses additional ML techniques inside the ensemble method, the SuperLearner, previously used in Dainotti et al. Additionally, we also test a novel ML model called Sorted L-One Penalized Estimation. Using these methods, we provide a catalog of estimated redshift values for those AGNs that do not have a spectroscopic redshift measurement. These estimates can serve as a redshift reference for the community to verify as updated Fermi catalogs are released with more redshift measurements.

Beaming Effect in Fermi Blazars

Abstract Blazars show extreme observational properties that are due to the beaming effect with the jet being close to the line of sight. It was found that the observed luminosity is anticorrelated with the synchrotron peak frequency but the debeamed luminosity and the frequency is positively correlated. In this work, we revisit this correlation for a large sample of 255 blazars from the fourth Fermi catalog with available Doppler factors. Our analysis comes to the following conclusions. (1) The observed radio, X-ray, γ-ray, and synchrotron peak luminosity are all anticorrelated with the peak frequency, but the debeamed luminosity is positively correlated with the debeamed peak frequency. The anticorrelation is due to a selection effect or a beaming effect. (2) The Compton dominance parameter is correlated with both the bolometric luminosity and Doppler factor, implying that the more highly Compton-dominated sources are more luminous. (3) The bolometric luminosity can be represented by the γ-ray luminosity for Fermi blazars.

Classifying Blazar Candidates from the 3FGL Unassociated Catalog into BL Lacertae Objects and Flat Spectrum Radio Quasars Using Swift and WISE Data

Abstract We utilize machine-learning methods to distinguish BL Lacertae (BL Lac) objects from flat spectrum radio quasars (FSRQs) within a sample of likely X-ray blazar counterparts to Fermi 3FGL unassociated gamma-ray sources. From our previous work, we have extracted 84 sources that were classified as ≥99% likely to be blazars. We then utilize Swift-XRT, Fermi, and The Wide-field Infrared Survey Explorer (WISE) data together to distinguish the specific type of blazar, FSRQs, or BL Lac objects. Various X-ray and gamma-ray parameters can be used to differentiate between these subclasses. These are also known to occupy different parameter space on the WISE color–color diagram. Using all these data together would provide more robust results for the classified sources. We utilized a random forest classifier to calculate the probability for each blazar to be associated with a BL Lac object or an FSRQ. Based on P bll, which is the probability for each source to be a BL Lac object, we placed our sources into five different categories based on this value as follows: P bll ≥ 99%: highly likely BL Lac object, P bll ≥ 90%: likely BL Lac object, P bll ≤ 1%: highly likely FSRQ, P bll ≤ 10%: likely FSRQ, and 90% < P bll < 10%: ambiguous. Our results categorize the 84 blazar candidates as 50 likely BL Lac objects and the other 34 as being ambiguous. A small subset of these sources have been listed as associated sources in the most recent Fermi catalog, 4FGL, and in these cases our results are in agreement on the classification.

A Stacking Search for Gamma-Ray Emission from Nearby Flare Stars and the Periodic Source TVLM 513-46546

Abstract So far, the Sun is the only isolated main-sequence star detected in gamma-rays, particularly during powerful flares. Young ultracool dwarfs are far more active so they are also plausible gamma-ray sources. We performed a spatial stack of 97 of the nearest X-ray and radio flare stars to search for GeV emission using nearly 12 yr of data from the Fermi Gamma-ray Space Telescope. The stacked residual maps showed no significant signal. Modeling the upper limits indicates a peak stellar flux at least a factor of 7 below the noise level. We also analyze the phase-folded light curve of the rapidly rotating radio star TVLM 513-46546, report a tentative (TS = 30) pulsed signal, and refine its period. We examine the possibility of a false-positive signal by analyzing nearby Fermi catalog sources and test fields, and by repeating the analysis using different periods. No other periodic signals are found, despite clear detections of the catalog sources, and the TS value for TVLM 513 increases systematically to the optimal period. The putative gamma-ray signal is nearly in phase with the optical peak, and out of phase with the radio pulses by 0.4 ± 0.05 rotations. These results argue for emission from relativistic protons streaming down flux tubes toward the photospheric active regions. The protons colliding with the atmosphere create neutral pions that decay into gamma-ray photons. This would be the first detection of a normal, isolated star in gamma-rays, and the strongest evidence yet for proton acceleration in stellar magnetospheres.

A blazar as the likely counterpart to 4FGL J0647.7−4418 instead of a gamma-ray binary

ABSTRACT The persistent gamma-ray source 4FGL J0647.7−4418 is tentatively associated in the latest Fermi catalogue with the subdwarf O-type X-ray binary HD 49798. However, an active galactic nucleus (AGN) candidate is also mentioned as an alternative identification in updated versions of the catalogue accompanying paper. If the first association were correct, this would add HD 49798 to the handful of currently known gamma-ray binaries, and therefore represent a significant breakthrough not only because of a new member addition, but also because of the apparent white dwarf companion in this system. Despite these perspectives, here, we show that the stellar association is likely wrong and that the proposed AGN object, well inside the Fermi 95 per cent confidence ellipse, is a more conceivable counterpart candidate to the Fermi source due to its strong blazar similarities.

Classification of New X-Ray Counterparts for Fermi Unassociated Gamma-Ray Sources Using the Swift X-Ray Telescope

Abstract Approximately one-third of the gamma-ray sources in the third Fermi-LAT catalog are unidentified or unassociated with objects at other wavelengths. Observations with the X-Ray Telescope on the Neil Gehrels Swift Observatory (Swift-XRT) have yielded possible counterparts in ∼30% of these source regions. The objective of this work is to identify the nature of these possible counterparts, utilizing their gamma-ray properties coupled with the Swift derived X-ray properties. The majority of the known sources in the Fermi catalogs are blazars, which constitute the bulk of the extragalactic gamma-ray source population. The galactic population on the other hand is dominated by pulsars. Overall, these two categories constitute the majority of all gamma-ray objects. Blazars and pulsars occupy different parameter space when X-ray fluxes are compared with various gamma-ray properties. In this work, we utilize the X-ray observations performed with the Swift-XRT for the unknown Fermi sources and compare their X-ray and gamma-ray properties to differentiate between the two source classes. We employ two machine-learning algorithms, decision tree and random forest (RF) classifier, to our high signal-to-noise ratio sample of 217 sources, each of which corresponds to Fermi unassociated regions. The accuracy scores for both methods were found to be 97% and 99%, respectively. The RF classifier, which is based on the application of a multitude of decision trees, associated a probability value (P bzr) for each source to be a blazar. This yielded 173 blazar candidates from this source sample, with P bzr ≥ 90% for each of these sources, and 134 of these possible blazar source associations had P bzr ≥ 99%. The results yielded 13 sources with P bzr ≤ 10%, which we deemed as reasonable candidates for pulsars, seven of which result with P bzr ≤ 1%. There were 31 sources that exhibited intermediate probabilities and were termed ambiguous due to their unclear characterization as a pulsar or a blazar.

Relativistic Jets in Gamma-Ray-Emitting Narrow-Line Seyfert 1 Galaxies

Before the launch of the Fermi Gamma-ray Space Telescope satellite only two classes of active galactic nuclei (AGN) were known to generate relativistic jets and thus to emit up to the γ -ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The discovery by the Large Area Telescope (LAT) on-board the Fermi satellite of variable γ -ray emission from a few radio-loud narrow-line Seyfert 1 galaxies (NLSy1) revealed the presence of an emerging third class of AGN with powerful relativistic jets. Considering that NLSy1 are usually hosted in late-type galaxies with relatively small black hole masses, this finding opened new challenging questions about the nature of these objects, the disc/jet connection, the emission mechanisms at high energies, and the formation of relativistic jets. In this review, I will discuss the broad-band properties of the γ -ray-emitting NLSy1 included in the Fourth Fermi LAT source catalog, highlighting major findings and open questions regarding jet physics, black hole mass estimation, host galaxy and accretion process of these sources in the Fermi era.

A complete sample of LSP blazars fully described in γ-rays

Context. We study the γ-ray and broadband spectral energy distribution (SED) properties of a complete sample of 104 bright, radio-selected low-synchrotron peaked (LSP) blazars, which have well-characterized SEDs from radio to X-rays. Most of the sources have already been detected in the γ-ray band by Fermi-LAT, however almost 20% of these blazars have no counterpart in any of the Fermi catalogs published so far. Aims. Using the Fermi Science Tools, we look for γ-ray emission for those objects not yet reported in any Fermi-LAT catalog, finding new detections and associations. We then study the multifrequency SED for all sources in our sample, fitting their synchrotron (Syn) and inverse Compton (IC) components. A complete sample of LSP blazars with a full description in γ-ray is unique. We use this sample to derive the distribution of the Compton dominance (CD) along with population properties such as Syn and IC peak power, and frequency distributions. Methods. We performed a binned likelihood analysis in the 0.3–500 GeV energy band with Fermi-LAT Pass 8 data, integrating over 7.5 yr of observations. We studied γ-ray light curves and test statistic (TS) maps to validate new detections and associations, thereby building a better picture of the high-energy activity in radio-selected LSP blazars. We fit the IC component for the new detections using all data at our disposal from X-rays to GeV γ-rays, enhancing the amount of information available to study the Syn to IC peak-power correlations. Results. We deliver a unique characterization in γ-rays for a complete sample of LSP blazars. We show that three previously unidentified 3FGL sources can be associated with blazars when using improved γ-ray positions obtained from TS maps. Six previously unreported γ-ray sources are detected at TS > 20 level, while another three show TS values between 10–20. We evaluate two cases in which source confusion is likely present. In four cases there is no significant γ-ray signature when integrating over 7.5 yr. Short-lived flares at ~1 month scale, however, have been detected in these sources. Finally, we measure the log(CD) for the sample, which has a Gaussian-like distribution with median log(CD) ≈ 0.1, implying that on average the peak-power for the Syn and IC components in LSP blazars is similar.