scholarly journals DISCOVERY OF NINE GAMMA-RAY PULSARS INFERMILARGE AREA TELESCOPE DATA USING A NEW BLIND SEARCH METHOD

2011 ◽  
Vol 744 (2) ◽  
pp. 105 ◽  
Author(s):  
H. J. Pletsch ◽  
L. Guillemot ◽  
B. Allen ◽  
M. Kramer ◽  
C. Aulbert ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Search Method ◽  
Blind Search

scholarly journals Search for Gamma-Ray Bursts and Gravitational Wave Electromagnetic Counterparts with High Energy X-ray Telescope of Insight-HXMT

2021 ◽  
Author(s):  
C Cai ◽  
S L Xiong ◽  
C K Li ◽  
C Z Liu ◽  
S N Zhang ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
High Energy ◽  
Search Method ◽  
Gamma Ray Bursts ◽  
Detection Sensitivity ◽  
Detector Response ◽  
High Time Resolution ◽  
X Ray ◽  
Blind Search

Abstract The High Energy X-ray telescope (HE) on-board the Hard X-ray Modulation Telescope (Insight-HXMT) can serve as a wide Field of View (FOV) gamma-ray monitor with high time resolution (μs) and large effective area (up to thousands cm2). We developed a pipeline to search for Gamma-Ray Bursts (GRBs), using the traditional signal-to-noise ratio (SNR) method for blind search and the coherent search method for targeted search. By taking into account the location and spectrum of the burst and the detector response, the targeted coherent search is more powerful to unveil weak and sub-threshold bursts, especially those in temporal coincidence with Gravitational Wave (GW) events. Based on the original method in literature, we further improved the coherent search to filter out false triggers caused by spikes in light curves, which are commonly seen in gamma-ray instruments (e.g. Fermi/GBM, POLAR). We show that our improved targeted coherent search method could eliminate almost all false triggers caused by spikes. Based on the first two years of Insight-HXMT/HE data, our targeted search recovered 40 GRBs, which were detected by either Swift/BAT or Fermi/GBM but too weak to be found in our blind search. With this coherent search pipeline, the GRB detection sensitivity of Insight-HXMT/HE is increased to about 1.5E-08 erg cm−2 (200 keV–3 MeV). We also used this targeted coherent method to search Insight-HXMT/HE data for electromagnetic (EM) counterparts of LIGO-Virgo GW events (including O2 and O3a runs). However, we did not find any significant burst associated with GW events.

scholarly journals Detection of gamma-ray transients with wild binary segmentation

2020 ◽  
Vol 493 (3) ◽  
pp. 4428-4441
Author(s):  
S Antier ◽  
K Barynova ◽  
P Fryzlewicz ◽  
C Lachaud ◽  
G Marchal-Duval
Keyword(s):  
Gamma Ray ◽  
Change Point Detection ◽  
Archival Data ◽  
Data Set ◽  
Temporal Properties ◽  
Background Removal ◽  
Segmentation Analysis ◽  
Binary Segmentation ◽  
Blind Search ◽  
Detection Search

ABSTRACT In the context of time domain astronomy, we present an offline detection search of gamma-ray transients using a wild binary segmentation analysis called F-WBSB targeting both short and long gamma-ray bursts (GRBs) and covering the soft and hard gamma-ray bands. We use NASA Fermi/GBM archival data as a training and testing data set. This paper describes the analysis applied to the 12 NaI detectors of the Fermi/GBM instrument. This includes background removal, change-point detection that brackets the peaks of gamma-ray flares, the evaluation of significance for each individual GBM detector, and the combination of the results among the detectors. We also explain the calibration of the ∼ 10 parameters present in the method using one week of archival data. Finally, we present our detection performance result for 60 d of a blind search analysis with F-WBSB by comparing to both the onboard and offline GBM search as well as external events found by others surveys such as Swift-BAT. We detect 42/44 onboard GBM events but also other gamma-ray flares at a rate of 1 per hour in the 4–50 keV band. Our results show that F-WBSB is capable of recovering gamma-ray flares, including the detection of soft X-ray long transients. FWBSB offers an independent identification of GRBs in combination with methods for determining spectral and temporal properties of the transient as well as localization. This is particularly useful for increasing the GRB rate and that will help the joint detection with gravitational-wave events.

scholarly journals A blind search for prompt gamma-ray counterparts of fast radio bursts withFermi-LAT data

2016 ◽  
Vol 460 (3) ◽  
pp. 2875-2880 ◽  
Author(s):  
Shotaro Yamasaki ◽  
Tomonori Totani ◽  
Norita Kawanaka
Keyword(s):  
Gamma Ray ◽  
Prompt Gamma ◽  
Radio Bursts ◽  
Blind Search

scholarly journals The Einstein@Home Survey for Gamma-ray Pulsars

2017 ◽  
Vol 13 (S337) ◽  
pp. 21-24
Author(s):  
Colin J. Clark ◽  
Jason Wu ◽  
Holger J. Pletsch ◽  
Lucas Guillemot
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
Large Fraction ◽  
Computing System ◽  
Data Reconstruction ◽  
Volunteer Computing ◽  
Radio Observations ◽  
Large Area ◽  
Space Telescope ◽  
Blind Search

AbstractSince the launch of the Fermi Gamma-ray Space Telescope in 2008, the onboard Large Area Telescope (LAT) has detected gamma-ray pulsations from more than 200 pulsars. A large fraction of these remain undetected in radio observations, and could only be found by directly searching the LAT data for pulsations. However, the sensitivity of such “blind” searches is limited by the sparse photon data and vast computational requirements. In this contribution we present the latest large-scale blind-search survey for gamma-ray pulsars, which ran on the distributed volunteer computing system, Einstein@Home, and discovered 19 new gamma-ray pulsars. We explain how recent improvements to search techniques and LAT data reconstruction have boosted the sensitivity of blind searches, and present highlights from the survey’s discoveries. These include: two glitching pulsars; the youngest known radio-quiet gamma-ray pulsar; and two isolated millisecond pulsars (MSPs), one of which is the only known radio-quiet rotationally powered MSP.

scholarly journals Blind search for radio-quiet and radio-loud gamma-ray pulsars with Fermi-LAT data

JETP Letters ◽  
2015 ◽  
Vol 100 (11) ◽  
pp. 689-694 ◽  
Author(s):  
G. I. Rubtsov ◽  
E. V. Sokolova
Keyword(s):  
Gamma Ray ◽  
Blind Search

scholarly journals Blind Search Methods for Binary Gamma-ray Pulsars

2017 ◽  
Vol 13 (S337) ◽  
pp. 382-383
Author(s):  
Lars Nieder ◽  
Colin J. Clark ◽  
Holger J. Pletsch
Keyword(s):  
Gamma Ray ◽  
Optical Observations ◽  
Large Area ◽  
Search Methods ◽  
Companion Star ◽  
Orbital Parameters ◽  
Radio Data ◽  
Blind Search

AbstractGamma-ray observations by the Fermi Large Area Telescope (LAT) have been used very successfully in the last 9 years to detect more than 200 gamma-ray pulsars. Sixty of these have been found by directly searching for pulsations in the gamma-ray data, but only one binary MSP has been found this way. Pulsars in binaries are often difficult to detect in radio data because of large eclipses, and some binary MSPs may even be radio quiet. For those, a gamma-ray blind search might be the only possibility for detection. While searches for isolated pulsars up to kilohertz frequencies are already computationally very challenging, blind searches for binary gamma-ray pulsars are simply infeasible without further knowledge of their orbital parameters. Here we present methods with which we can conduct searches for candidate binary gamma-ray pulsars for which orbital constraints are known from optical observations of a likely companion star. We also highlight some example sources where these methods have been used.

scholarly journals Blind Search Methods for Binary Gamma-ray Pulsars

2017 ◽  
Author(s):  
Lars Nieder ◽  
Colin Clark ◽  
Keyword(s):  
Gamma Ray ◽  
Search Methods ◽  
Blind Search

On the possible gamma-ray source in Cygnus

1967 ◽  
Vol 31 ◽  
pp. 469-471
Author(s):  
J. G. Duthie ◽  
M. P. Savedoff ◽  
R. Cobb
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Right Ascension

A source of gamma rays has been found at right ascension 20h15m, declination +35°, with an uncertainty of 6° in each coordinate. Its flux is (1·5 ± 0·8) x 10-4photons cm-2sec-1at 100 MeV. Possible identifications are reviewed, but no conclusion is reached. The mechanism producing the radiation is also uncertain.

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