High-energy Neutrinos from Gamma-Ray-faint Accretion-powered Hypernebulae

Sridhar, Navin; Metzger, Brian D.; Fang, Ke

doi:10.3847/1538-4357/ad03e8

Cited by 7 publications

(1 citation statement)

References 141 publications

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“…An alternative scenario for FRB progenitors was introduced by Sridhar et al (2021) in which FRB pulses are emitted along the jet axis of an accreting compact object, and the associated PRS synchrotron emission is powered by particles heated at the termination shock of the outflowing super-Eddington disk wind ("Hypernebula"; Sridhar & Metzger 2022;Sridhar et al 2024). Unlike a magnetar-powered engine, the activity rate of FRBs from an accretion-powered engine does not necessarily diminish as the system ages.…”

Section: Models For a Putative Persistent Radio Sourcementioning

confidence: 99%

Mapping Obscured Star Formation in the Host Galaxy of FRB 20201124A

Dong 董,

Eftekhari,

Fong

et al. 2024

ApJ

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We present high-resolution 1.5–6 GHz Karl G. Jansky Very Large Array and Hubble Space Telescope (HST) optical and infrared observations of the extremely active repeating fast radio burst (FRB) FRB 20201124A and its barred spiral host galaxy. We constrain the location and morphology of star formation in the host and search for a persistent radio source (PRS) coincident with FRB 20201124A. We resolve the morphology of the radio emission across all frequency bands and measure a star formation rate (SFR) ≈ 8.9 M ⊙ yr−1, approximately ≈2.5–6 times larger than optically inferred SFRs, demonstrating dust-obscured star formation throughout the host. Compared to a sample of all known FRB hosts with radio emission, the host of FRB 20201124A has the most significantly obscured star formation. While HST observations show the FRB to be offset from the bar or spiral arms, the radio emission extends to the FRB location. We propose that the FRB progenitor could have formed in situ (e.g., a magnetar born from a massive star explosion). It is still plausible, although less likely, that the progenitor of FRB 20201124A migrated from the central bar of the host. We further place a limit on the luminosity of a putative PRS at the FRB position of L 6.0GHz ≲ 1.8 ×1027 erg s−1 Hz−1, among the deepest PRS luminosity limits to date. However, this limit is still broadly consistent with both magnetar nebulae and hypernebulae models assuming a constant energy injection rate of the magnetar and an age of ≳105 yr in each model, respectively.

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Section: Models For a Putative Persistent Radio Sourcementioning

confidence: 99%

Mapping Obscured Star Formation in the Host Galaxy of FRB 20201124A

Dong 董,

Eftekhari,

Fong

et al. 2024

ApJ

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The Northern Cross Fast Radio Burst project

Pelliciari,

Bernardi,

Pilia

et al. 2024

A&A

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Fast radio bursts (FRBs) are energetic, millisecond-duration radio pulses observed at extragalactic distances and whose origins are still a subject of heated debate. A fraction of the FRB population have shown repeating bursts, however it's still unclear whether these represent a distinct class of sources. We investigated the bursting behaviour of FRB 20220912A, one of the most active repeating FRBs known thus far. In particular, we focused on its burst energy distribution, linked to the source energetics, and its emission spectrum, with the latter directly related to the underlying emission mechanism. We monitored FRB 20220912A at $408$ MHz with the Northern Cross radio telescope and at $1.4$ GHz using the $32$-m Medicina Grueff radio telescope. Additionally, we conducted $1.2$ GHz observations taken with the upgraded Giant Meter Wave Radio Telescope (uGMRT) searching for a persistent radio source coincident with FRB 20220912A, which included high energy observations in the $0.3$--$10$ keV, $0.4$--$100$ MeV and $0.03$--$30$ GeV energy range. We report 16 new bursts from FRB 20220912A at $408$ MHz during the period between October 16$^ th $ 2022 and December 31$^ st $ 2023. Their cumulative spectral energy distribution follows a power law with slope $ 0.2$ and we measured a repetition rate of $0.19 $ for bursts having a fluence of $ F 17$ Jy ms. Furthermore, we report no detections at $1.4$ GHz for $ F 20$ Jy ms. These non-detections imply an upper limit of $ < -2.3$, with beta being the 408 MHz -- 1.4 GHz spectral index of FRB 20220912A. This is inconsistent with positive beta values found for the only two known cases in which an FRB has been detected in separate spectral bands. We find that FRB 20220912A shows a decline of four orders of magnitude in its bursting activity at $1.4$ GHz over a timescale of one year, while remaining active at $408$ MHz. The cumulative spectral energy distribution (SED) shows a flattening for spectral energy $E_ $ erg Hz$^ $, a feature seen thus far in only two hyperactive repeaters. In particular, we highlight a strong similarity between FRB 20220912A and FRB 20201124A, with respect to both the energy and repetition rate ranges. We also find a radio continuum source with $240 36$ mu Jy flux density at 1.2 GHz, centered on the FRB 20220912A coordinates. Finally, we place an upper limit on the gamma to radio burst efficiency eta to be $ 10^9$ at 99.7<!PCT!> confidence level, in the $0.4$ -- $30$ MeV energy range. The strong similarity between the cumulative energy distributions of FRB 20220912A and FRB 20201124A indicate that bursts from these sources are generated via similar emission mechanisms. Our upper limit on beta suggests that the spectrum of FRB 20220912A is intrinsically narrow-band. The radio continuum source detected at 1.2 GHz is likely due to a star formation environment surrounding the FRB, given the absence of a source compact on millisecond scales brighter than 48 mu Jy beam$^ $ (cit). Finally, the upper limit on the ratio between the gamma and radio burst fluence disfavours a giant flare origin for the radio bursts unlike observed for the Galactic magnetar SGR 1806-20.

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Upper limit on the coronal cosmic ray energy budget in Seyfert galaxies

Inoue,

Takasao,

Khangulyan

2024

Publications of the Astronomical Society of Japan

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The IceCube Collaboration has reported possible detections of high-energy neutrinos from nearby Seyfert galaxies. While central hot coronae are proposed as the primary neutrino production site, the exact coronal cosmic ray energy budget has been loosely constrained. In this study, we propose a new stringent upper bound on the coronal cosmic ray energy budget of Seyfert galaxies, considering both accretion dynamics and observed properties of radio-quiet Seyfert galaxies. Notably, even under the calorimetric condition where cosmic rays lose all their energy, our limit indicates that the coronal neutrino flux of NGC 1068 is about an order of magnitude fainter than the observed levels. This discrepancy suggests the need for further theoretical and observational investigations on the IceCube signals from Seyfert galaxies.

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High-energy Neutrinos from Gamma-Ray-faint Accretion-powered Hypernebulae

Cited by 7 publications

References 141 publications

Mapping Obscured Star Formation in the Host Galaxy of FRB 20201124A

Mapping Obscured Star Formation in the Host Galaxy of FRB 20201124A

The Northern Cross Fast Radio Burst project

Upper limit on the coronal cosmic ray energy budget in Seyfert galaxies

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