Imprints of Gravitational Millilensing on the Light Curve of Gamma-Ray Bursts

Kalantari, Zeinab; Ibrahim, Alaa; Tabar, M. Reza Rahimi; Rahvar, S.

doi:10.3847/1538-4357/ac1c06

Cited by 17 publications

(27 citation statements)

References 28 publications

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“…Based on the time delay and the flux ratio, one can roughly estimate the redshift mass of the lens in the rest frame (Mao 1992;Paynter et al 2021;Kalantari et al 2021;Chen et al 2021). Combining Eq.…”

Section: Lens Mass Estimationmentioning

confidence: 99%

Gravitationally Lensed Orphan Afterglows of Gamma-Ray Bursts

Gao¹,

Geng²,

Hu³

et al. 2022

Preprint

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The cosmological nature of gamma-ray bursts (GRBs) implies that a small portion of them could be gravitationally lensed by foreground objects during their propagation. The gravitational lensing effect on the GRB prompt emission and on-axis afterglows has been discussed, and some candidates have been found in the literature. In this work, considering the high detection rate of GRB orphan afterglows in future wide-field survey era, we investigate the gravitationally lensed orphan afterglows in view of three lens models, i.e., the point-mass model, the singular isothermal sphere model, and the Chang-Refsdal model. The structure of the GRB jet itself is also incorporated in calculating the lensed afterglow light curves. It is found that lensed optical/X-ray orphan afterglows in principle could be diagnosed through their temporal characteristics, and the optical band is the best band to observe the galaxy-lensed orphan afterglows. Moreover, the event rate for galaxy-lensed orphan afterglows is estimated to be 0.7 yr −1 for the whole sky. The optimistic detection rates of the Wide Field Survey Telescope (WFST) and Large Synoptic Survey Telescope (LSST) for galaxy-lensed orphan afterglows in the optical band are 0.02 yr −1 and 0.08 yr −1 , respectively.

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Section: Lens Mass Estimationmentioning

confidence: 99%

Gravitationally Lensed Orphan Afterglows of Gamma-Ray Bursts

Gao¹,

Geng²,

Hu³

et al. 2022

Preprint

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“…Hardness test has been widely used to justify the lensing effect (Paynter et al 2021;Kalantari et al 2021;Wang et al 2021;Veres et al 2021), based on the hypothesis that the flux ratio between gravitationally lensed pulses should not depend on energy (Paczynski 1987). In this work, we adopt three energy channels to carry out the hardness test: Low energy channel (8-50 keV), Medium energy channel (50-110 keV) and High energy channel (110-323 keV).…”

Section: Hardness Testmentioning

confidence: 99%

“…Paynter et al (2021) claims the first convincing evidence for millilensing events in the light curve of BATSE GRB 950830 and thus claims the existence of intermediatemass black holes 2 . Later on, an increase of millilensing GRB candidates from the data of Fermi/GBM have been claimed (Kalantari et al 2021;Wang et al 2021;Yang et al 2021;Veres et al 2021). For instance, Wang et al (2021) and Yang et al (2021) made independent analysis for GRB 200716C and argued it showing millilensing signatures.…”

Section: Introductionmentioning

confidence: 97%

“…Most recently, Kalantari et al (2021) applied autocorrelation method to the Fermi sample and find one more millilensing candidate (GRB 090717A). But Mukherjee & Nemiroff (2021a) later argued that the two pulses in GRB 090717 differ at about 5σ confidence level, therefore GRB 090717 does not present a compelling example of gravitational lensing.…”

Section: Introductionmentioning

confidence: 99%

“…But Mukherjee & Nemiroff (2021a) later argued that the two pulses in GRB 090717 differ at about 5σ confidence level, therefore GRB 090717 does not present a compelling example of gravitational lensing. Nevertheless, in the analysis of Kalantari et al (2021), spectral properties for each source have not been taken into account (not even the hardness test). In existing case studies, it can be seen that spectral analysis plays a vital role in identifying the authenticity of candidates.…”

Section: Introductionmentioning

confidence: 99%

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A Search for Millilensing Gamma-Ray Bursts in the Observations of Fermi GBM

Lin,

Li,

Gao

et al. 2021

Preprint

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Millilensing of Gamma-Ray Bursts (GRBs) is expected to manifest as multiple emission episodes in a single triggered GRB with similar light-curve patterns and similar spectrum properties. Identifying such lensed GRBs could help improve constraints on the abundance of compact dark matter. Here we present a systemic search for millilensing among 3000 GRBs observed by the Fermi GBM up to 2021 April. Eventually we find 4 interesting candidates by performing auto-correlation test, hardness test, and time-integrated/resolved spectrum test to the whole sample. GRB 081126A and GRB 090717A are ranked as the first class candidate based on their excellent performance both in temporal and spectrum analysis. GRB 081122A and GRB 110517B are ranked as the second class candidates (suspected candidates), mainly because their two emission episodes show clear deviations in part of the time-resolved spectrum or in the time-integrated spectrum. Considering a point mass model for the gravitational lens, our results suggest that the density parameter of lens objects with mass M L ∼ 10 6 M is larger than 1.5 × 10 −3 .

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Discriminating power of milli-lensing observations for dark matter models

Loudas

Pavlidou

Casadio

et al. 2022

A&A

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Context. The nature of dark matter (DM) is still under intense debate. Subgalactic scales are particularly critical, as different, currently viable DM models make diverse predictions on the expected abundance and density profile of DM haloes on these scales. Aims. We investigate the ability of subgalactic DM haloes to act as strong lenses on background compact sources, producing gravitational lensing events on milli-arcsecond scales (milli-lenses), for different DM models. For each DM scenario, we explore whether a sample of ∼ 5000 distant sources is sufficient to detect at least one milli-lens. Methods. We developed a semi-analytical model to estimate the milli-lensing optical depth as a function of the source's redshift for various DM models. We employed the Press-Schechter formalism, as well as results from recent N-body simulations to compute the halo mass function, taking into account the appropriate spherically averaged density profile of haloes for each DM model. We treated the lensing system as a point-mass lens and invoked the effective surface mass density threshold to calculate the fraction of a halo that acts as a gravitational lens. We studied three classes of dark matter models: cold DM, warm DM, and self-interacting DM. Results. We find that haloes consisting of warm DM turn out to be optically thin for strong gravitational milli-lensing (zero expected lensing events). Cold DM haloes may produce lensing events depending on the steepness of the concentration-mass relation. Selfinteracting DM haloes can efficiently act as gravitational milli-lenses only if haloes experience gravothermal collapse, resulting in highly dense central cores.

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Imprints of Gravitational Millilensing on the Light Curve of Gamma-Ray Bursts

Cited by 17 publications

References 28 publications

Gravitationally Lensed Orphan Afterglows of Gamma-Ray Bursts

Gravitationally Lensed Orphan Afterglows of Gamma-Ray Bursts

A Search for Millilensing Gamma-Ray Bursts in the Observations of Fermi GBM

Discriminating power of milli-lensing observations for dark matter models

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