The Einstein@home Gamma-Ray Pulsar Survey. I. Search Methods, Sensitivity, and Discovery of New Young Gamma-Ray Pulsars

Clark, C. J.; Wu, J.; Pletsch, H. J.; Guillemot, L.; Allen, B.; Aulbert, C.; Beer, C.; Böck, O.; Cuéllar, A.; Eggenstein, H.-B.; Fehrmann, H.; Krämer, M.; Machenschalk, B.; Nieder, L.

doi:10.3847/1538-4357/834/2/106

Cited by 71 publications

(79 citation statements)

References 56 publications

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“…Seven additional 3FGL sources are associated with blazars in [66], although they are all at low latitude (see second criterium below); 31 more in [67], associated with blazars, quasars and galaxies, 10 more blazars in [68], and 18 more miscellaneous AGNs collected in [69] are rejected. Also, 13 more 3FGL-only sources are removed with a blind search of Einstein@Home [70] as they are associated to low-latitude pulsars. Within the same project, one more source, a radio-quiet pulsar, is rejected [71].…”

Section: Search Of Dm Subhalo Candidates In Fermi -Lat Source Catalogsmentioning

confidence: 99%

Unidentified gamma-ray sources as targets for indirect dark matter detection with theFermi-Large Area Telescope

Coronado-Blázquez

Domínguez

Aguirre-Santaella

et al. 2019

J. Cosmol. Astropart. Phys.

115

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One of the predictions of the ΛCDM cosmological framework is the hierarchical formation of structure, giving rise to dark matter (DM) halos and subhalos. When the latter are massive enough they retain gas (i.e., baryons) and become visible. This is the case of the dwarf satellite galaxies in the Milky Way (MW). Below a certain mass, halos may not accumulate significant amounts of baryons and remain completely dark. However, if DM particles are Weakly Interacting Massive Particles (WIMPs), we expect them to annihilate in subhalos, producing gamma rays which can be detected with the Fermi satellite. Using the three most recent point-source Fermi Large Area Telescope (LAT) catalogs (3FGL, 2FHL and 3FHL), we search for DM subhalo candidates among the unidentified sources, i.e., sources with no firm association to a known astrophysical object. We apply several selection criteria based on the expected properties of the DM-induced emission from subhalos, which allow us to significantly reduce the list of potential candidates. Then, by characterizing the minimum detection flux of the instrument and comparing our sample to predictions from the Via Lactea II (VL-II) N-body cosmological simulation, we place conservative and robust constraints on the σv − m DM parameter space. For annihilation via the τ + τ − channel, we put an upper limit of 4 × 10 −26 (5 × 10 −25 ) cm 3 s −1 for a mass of 10 (100) GeV. A critical improvement over previous treatments is the repopulation we made to include low-mass subhalos below the VL-II mass resolution. With more advanced subhalo candidate filtering the sensitivity reach of our method can potentially improve these constraints by a factor 3 (2) for τ + τ − (bb) channel.are an example of the most massive members of this population [11]. Yet, these dSphs are exceptional objects, in that they are massive enough to retain baryons (i.e., gas) and form stars. Conversely, the vast majority of the Galactic DM subhalos are not expected to host baryons and therefore remain completely dark [12]. Given their much larger number density, many of these small subhalos will be much closer to the Earth than the bigger ones, making them potentially interesting for dark matter searches.Should the Weakly Interacting Massive Particle (WIMP) DM model be correct (see, e.g., [13, 14] for a review), these objects may be detectable in the gamma-ray data. WIMPs can achieve the correct relic DM abundance (the so-called "WIMP miracle") through selfannihilation in the early Universe. Self-annihilation of WIMPs gives rise to a Standard Model (SM) particle-antiparticle pair which, among other possible subsequent by-products, typically yields gamma-ray photons. The ongoing self-annihilation of WIMPs in subhalos could be bright enough to be detectable.Since its launch in 2008, the Large Area Telescope on board the NASA Fermi Gammaray Space Telescope (Fermi-LAT) has been surveying the sky searching for gamma-ray sources [15]. The Fermi-LAT is a pair conversion telescope designed to observe the energy band from 20 MeV to gre...

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Section: Search Of Dm Subhalo Candidates In Fermi -Lat Source Catalogsmentioning

confidence: 99%

Unidentified gamma-ray sources as targets for indirect dark matter detection with theFermi-Large Area Telescope

Coronado-Blázquez

Domínguez

Aguirre-Santaella

et al. 2019

J. Cosmol. Astropart. Phys.

115

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“…However this may not be so for searches which are compute-power limited, for example in the search for CWs or the search for gamma-ray pulsars. These computationally-limited searches often employ multiple hierarchical stages, which mix semi-coherent and coherent stages, each employing its own metric for template placement [28,39,46,69,70,[78][79][80][81][82][83][84][85][86][87][88][89][90]. Those hierarchical stages sometimes operate at substantial mismatches in the range m ∈ [0.5, 0.7], and here, the spherical approximation is an improvement on the conventional quadratic approximation.…”

Section: Why Does It Matter?mentioning

confidence: 99%

Spherical ansatz for parameter-space metrics

Allen

2019

Phys. Rev. D

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A fundamental quantity in signal analysis is the metric g ab on parameter space, which quantifies the fractional "mismatch" m between two (time-or frequency-domain) waveforms. When searching for weak gravitational-wave or electromagnetic signals from sources with unknown parameters λ (masses, sky locations, frequencies, etc.) the metric can be used to create and/or characterize "template banks". These are grids of points in parameter space; the metric is used to ensure that the points are correctly separated from one another. For small coordinate separations dλ a between two points in parameter space, the traditional ansatz for the mismatch is a quadratic form m = g ab dλ a dλ b . This is a good approximation for small separations but at large separations it diverges, whereas the actual mismatch is bounded. Here we introduce and discuss a simple "spherical" ansatz for the mismatch m = sin 2 ( g ab dλ a dλ b ). This agrees with the metric ansatz for small separations, but we show that in simple cases it provides a better (and bounded) approximation for large separations, and argue that this is also true in the generic case. This ansatz should provide a more accurate approximation of the mismatch for semi-coherent searches, and may also be of use when creating grids for hierarchical searches that (in some stages) operate at relatively large mismatch. I. MATCHED FILTERING AND THE OVERLAP BETWEEN TEMPLATESMore than two decades ago, when the first generation of interferometric gravitational wave (GW) detectors were still in the planning stages, a handful of pioneers investigated the techniques that would be needed to detect GW signals [1][2][3][4][5][6][7][8][9][10]. At that time there were three main challenges. First, the signals were weak in comparison with the noise from the detectors, so needed to be "teased out" of the data stream with optimal or nearoptimal methods. Second, the parameters describing the signals (such as the object masses in a binary system, or the rotation frequency and spindown rate of a neutron star) were not known. This required repeated searches for signals with many different parameter combinations, creating a significant computational challenge. Lastly, even if the parameters were known precisely, for some sources the waveforms could only be calculated approximately. The errors could be estimated but not sharply quantified.The solution to the first problem is to use "matched filtering" [3,[6][7][8][11][12][13][14][15][16]. In the simplest case [17] the time-dependent output S(t) of the detector is correlated with a template T (t) to produce a statistic ρ = (T, S).(1.1)If the template is normalized (T, T ) = 1 then ρ is called the signal-to-noise ratio (SNR). This is reviewed in a signal-processing context in [18,19] and in the GW context in [20] and [21]. The positive-definite inner product in Eq. (1.1) can be expressed in different ways. For example if the instrument noise is white (or the signal is confined to a narrow enough range of frequency that the noise is white in that band) then...

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“…Another is that the immense computing power available from citizens' idle PC's was brought to bear by the Einstein@ Home volunteer computing system: over 10 kyr of CPU time have been used. These and other improvements have doubled the number of known radio-quiet gamma-ray pulsars in the last few years, as described in [14] and references therein. Spectacularly, they have even begun to detect MSPs in blind searches -the first was PSR J1311-3430 [20].…”

Section: Discovering Gamma-ray Pulsarsmentioning

confidence: 99%

“…Only six are not radio-quiet, i.e., their radio flux density at 1400 MHz is S 1400 > 30µJy. The two recent radio-loud blind search pulsars are PSRs J0002+6216 and J0631+0646 [14].…”

Section: Discovering Gamma-ray Pulsarsmentioning

confidence: 99%

Gamma-ray pulsars with Fermi

Smith¹,

Guillemot²,

Kerr³

et al. 2017

Proceedings of 11th INTEGRAL Conference Gamma-Ray Astrophysics in Multi-Wavelength Perspective — PoS(INTEGRAL2016)

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In 8 years of operation, the Large Area Telescope (LAT) on the Fermi satellite has impacted our understanding of gamma-ray pulsars dramatically. The LAT now sees over two hundred pulsars: the largest class of GeV sources in the Milky Way. They are diverse -radio loud versus quiet, young versus millisecond, in evolving binary systems versus isolated, and so on. Relatively few of the GeV pulsars have also been seen in soft gamma rays. After an overview, we present 10 new radio pulsars, six young and four recycled, for which we detect gamma-ray pulsations.

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The Einstein@home Gamma-Ray Pulsar Survey. I. Search Methods, Sensitivity, and Discovery of New Young Gamma-Ray Pulsars

Cited by 71 publications

References 56 publications

Unidentified gamma-ray sources as targets for indirect dark matter detection with theFermi-Large Area Telescope

Unidentified gamma-ray sources as targets for indirect dark matter detection with theFermi-Large Area Telescope

Spherical ansatz for parameter-space metrics

Gamma-ray pulsars with Fermi

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