arXiv subjects

Peter L. Biermann

Publications and source records attributed to Peter L. Biermann.

At least 19 recordsLinked to original sources

arXiv2026

Correlation Between Hard X-Ray and Cosmic Neutrino Sources: From Obscured AGN to Blazars

The origin of high-energy astrophysical neutrinos remains a key open question in multimessenger astrophysics. A correlation between unabsorbed hard X-ray and high-energy neutrino luminosity has been reported in six active galactic nuclei with the highest individual IceCube significances, linking neutrino production to compact, photon-rich environments near supermassive black holes. We study whether the threshold-near IceCube excesses associated with seven NuSTAR-observed blazars are statistically consistent with that relation. Calibrating the $L_\mathrm{hX}$-$L_\nu$ relation on the six published sources via a Bayesian regression with errors on both axes, the slope is consistent with $\beta = 1$ and the intrinsic scatter is $\sim 0.6$\,dex. All seven new blazars are posterior-predictively consistent with this calibration ($\chi^2_7 = 1.58$, $p = 0.98$) under the working hypothesis that the published IceCube $\hat{n}_s$ values reflect the signal. A null-injection test confirms that, at the present calibration sample size, the consistency test does not by itself adjudicate between signal and selected-background origins. A distance-free $L_\mathrm{hX}/L_\nu$ ratio diagnostic places both populations within the photohadronic prediction band, statistically indistinguishable. Two diagnostics that control the common $d_L^{\,2}$ distance bias, a redshift-partial rank correlation ($\tau|z = 0.69$, $\sim\!2.7\,\sigma$) and a flux-space permutation test on the 13-source joint sample ($p = 6.3\times10^{-4}$, $3.23\,\sigma$), indicate a residual $L_\mathrm{hX}$-$L_\nu$ association beyond the distance-induced trend. We interpret these results as a conditional consistency check; a detection-level statement requires either an enlarged calibration set or an X-ray-weighted IceCube stacking likelihood with internal data.

astro-ph.HE↗

arXiv2026

Upstream neutrino production and delayed jet emission in the blazar GB6 J1542+6129

We present a multimessenger case study of the blazar GB6 J1542+6129, examining whether its multiwavelength behavior is consistent with neutrino production in a compact region near the central black hole, or with the parsec-scale radio jet. We perform a multimessenger analysis combining ~17 years of Fermi-LAT gamma-ray data with ~14 years of VLBI/MOJAVE. These are compared to the temporal properties of a suspected IceCube neutrino flare with a duration of $147^{+110}_{-25}$ days, enabling a direct test of spatial and causal connections between neutrino and electromagnetic emission regions. We find that the suspected neutrino flare appears to precede both a $\gamma$-ray flare and a pronounced increase in the VLBI core Doppler factor by up to ~1 year. The duration of the post-flare $\gamma$-ray activity is comparable to that of the neutrino flare, which, in our framework, is consistent with both signatures originating from a single propagating disturbance whose temporal structure is preserved during the propagation. The gamma-ray spectral energy distribution remains consistent in shape across the full, flare, and post-flare intervals, indicating stable particle acceleration conditions. The temporal ordering, taken at face value, places the neutrino production site upstream of the VLBI core. The observations of GB6 J1542+6129 are consistent with a disturbance-driven, multi-zone scenario in which neutrinos are produced in a compact, photon-rich inner region upstream of the parsec-scale VLBI core, plausibly at the coronal region, while the same disturbance later enhances Doppler-boosted leptonic emission once it reaches the radio core. While the data alone do not strictly establish this scenario on a population level, they show how time-domain multimessenger observations of a single AGN can localize neutrino emission relative to the parsec-scale radio jet in a particular source.

astro-ph.HE↗

arXiv2025

A Seyfert galaxy as a hidden counterpart to a neutrino-associated blazar

The origin and production mechanisms of high-energy astrophysical neutrinos remain open questions in multimessenger astronomy. Previous studies have hinted at a possible linear correlation between the hard X-ray and high-energy neutrino emission in active galactic nuclei. New \textit{NuSTAR} observations, first presented here, reveal that blazar PKS 1424+240, located within a prominent IceCube neutrino hotspot, is far fainter in hard X-rays than expected from this trend. Motivated by this apparent ambiguity, we identify the nearby Seyfert galaxy NGC 5610, also coincident with the hotspot, whose unabsorbed hard X-ray flux exceeds that of PKS 1424+240 by about an order of magnitude. When the local IceCube neutrino flux is apportioned between the two AGN in proportion to their hard X-ray emission, both align with the previously suggested X-ray-neutrino correlation. This suggests that certain IceCube hotspots may be unresolved blends of multiple AGN, and supports a multimessenger scenario in which high-energy neutrinos and hard X-rays originate from the same hadronic interactions, with the X-ray emission produced through cascade reprocessing.

astro-ph.HE↗

arXiv2025

Astrophysical Black holes: An Explanation for the Galaxy Quenching

In light of increasing observational evidence supporting the existence of ultra-compact objects, we adopt the term astrophysical black hole to refer to any object having a huge mass confined within a sufficiently small region of spacetime. This terminology encompasses both the classical black hole solutions predicted by general relativity, as well as alternative compact objects that may not possess an event horizon. We propose models of Astrophysical Black holes (ABHs) without event horizons (EHs), as a more viable explanation for the long-term quenching phenomenon in galaxies. At the same time, the short-term quenching is explained here in terms of an efficient feedback expected in the models of stellar-mass astrophysical black holes (StMABHs). We have calculated the radiative flux from the disk in a general spherically symmetric metric background and used it to contrast the distinctive features of the BHs and ABHs scenarios. We demonstrate the relative ease of wind generation from the accretion disk surrounding an ABH without an event horizon, compared to a BH, and highlight the significant strength of these winds. The nature of the feedbacks arising from accretion onto a BH and an ABH in the `quasar' and `radio' modes are compared and some possible observational signatures of the StMABHs are pointed out.

gr-qc↗

arXiv2024

Possible correlation between unabsorbed hard X-rays and neutrinos in radio-loud and radio-quiet AGN

The first high-energy neutrino source identified by IceCube was a blazar -- an active galactic nucleus driving a relativistic jet towards Earth. Jets driven by accreting black holes are commonly assumed to be needed for high-energy neutrino production. Recently, IceCube discovered neutrinos from Seyfert galaxies, which appears unrelated to jet activity. Here, we show that the observed luminosity ratios of neutrinos and hard X-rays from blazars TXS 0506+056 and GB6 J1542+6129 are consistent with neutrino production in a $γ$-obscured region near a central supermassive black hole, with the X-ray flux corresponding to reprocessed $γ$-ray emission with flux comparable to that of neutrinos. Similar neutrino - hard X-ray flux ratios are found for four Seyfert galaxies, NGC 1068, NGC 4151, CGCG 420-015 and NGC 3079, raising the possibility of a common neutrino production mechanism that may not involve a strong jet.

astro-ph.HE↗

arXiv2023

Neutrino Emissions of TXS 0506+056 caused by a Supermassive Binary Black Hole Inspiral?

The IceCube neutrino observatory detected two distinct flares of high-energy neutrinos from the direction of the blazar TXS 0506+056: a $\sim 300$ TeV single neutrino on September 22, 2017 and a $3.5σ$ signature of a dozen TeV neutrinos in 2014/2015. In a previous work, it was shown that these two episodes of neutrino emission could be due to an inspiral of a supermassive binary black hole (SMBBH) close to its merger at the core of TXS 0506+056. Such an inspiral can lead to quasi-periodic particle emission due to jet precession close to the final coalescence. This model made predictions on when the next neutrino emission episode must occur. On September 18, 2022, IceCube detected an additional, $\sim 170$ TeV neutrino in directional coincidence with the blazar TXS 0506+056, being consistent with the model prediction. Additionally, in April 2021, the Baikal Collaboration reported the detection of a $224\pm 75$ TeV neutrino, with TXS 0506+056 being in the uncertainty range of the event direction. We show that these four distinct flares of neutrino emission from TXS 0506+056 are consistent with a precessing jet scenario, driven by an inspiraling SMBBH. Using improved modeling, we are now able to constrain the total mass together with the mass ratio for the binary. We predict when the next neutrino flares from TXS 0506+056 should be happening. Finally, we estimate the detection potential of the Laser-interferometer Space Antenna (LISA) for the merger in the future.

astro-ph.HE↗

arXiv2023

Searching for temporary gamma-ray dark blazars associated with IceCube neutrinos

Tensions between the diffuse gamma-ray sky observed by the Fermi Large Area Telescope (LAT) and the diffuse high-energy neutrino sky detected by the IceCube South Pole Neutrino Observatory question our knowledge about high-energy neutrino sources in the gamma-ray regime. While blazars are among the most energetic persistent particle accelerators in the Universe, studies suggest that they could account for up to for 10-30% of the neutrino flux measured by IceCube. Our recent results highlighted that the associated IceCube neutrinos arrived in a local gamma-ray minimum (dip) of three strong neutrino point-source candidates. We increase the sample of neutrino-source candidates to study their gamma-ray light curves. We generate the one-year Fermi-LAT light curve for 8 neutrino source candidate blazars (RBS 0958, GB6 J1040+0617, PKS 1313-333, TXS 0506+056, PKS 1454-354, NVSS J042025-374443, PKS 0426-380 and PKS 1502+106), centered on the detection time of the associated IceCube neutrinos. We apply the Bayesian block algorithm on the light curves to characterize their variability. Our results indicate that GB6 J1040+0617 was in the phase of high gamma-ray activity, while none of the other 7 neutrino source candidates were statistically bright during the detection of the corresponding neutrinos and that indeed even most of the times neutrinos arrived in a faint gamma-ray phase of the light curves. This suggests that the 8 source-candidate blazars (associated with 7 neutrino events) in our reduced sample are either not the sources of the corresponding IceCube neutrinos, or that an in-source effect (e.g. suppression of gamma rays due to high gamma-gamma opacity) complicates the multimessenger scenario of neutrino emission for these blazars.

astro-ph.HE↗

arXiv2022

Extragalactic neutrino emission induced by Supermassive and Stellar Mass Black Hole mergers

The recent detections of binary stellar mass black hole mergers by the LIGO and Virgo Collaborations suggest that such mergers are common occurrences. Galaxy mergers further indicate that supermassive black holes in centers of galaxies also merge and are typically expected to have had at least one merger in their lifetime, possibly many. In the presence of a jet, these mergers are almost always accompanied by a change of the jet direction and a connected jet precession motion, leading to interactions of the jet with ambient matter and producing very high-energy particles, and consequently high-energy gamma-rays and neutrinos. In this work, we investigate the possibility under which conditions such mergers could be the sources of the diffuse astrophysical neutrino flux measured by the IceCube Neutrino Observatory. The main free parameters in the calculation concern the frequency of the mergers and the fraction of energy that is transferred from the gravitationally released energy to neutrinos. We show that the merger rate for SMBBHs must lie between $\sim 10^{-7}$ and $10^{-5}$ Gpc$^{-3}$ yr$^{-1}$. The ratio of energy going to neutrinos during such mergers lies then between $\sim 10^{-6} - 3\cdot 10^{-4}$. For stellar mass BBH mergers, the rate needs to be $\sim 10-100$ Gpc$^{-3}$ yr$^{-1}$ and the expected ratio of neutrino to gravitational wave energy lies in a comparable range as for SMBBHs, $\sim 2 \cdot 10^{-5} - 10^{-3}$. These values lie in a reasonable parameter range, so that the production of neutrinos at the level of the detected neutrino flux is a realistic possibility.

astro-ph.HE↗

arXiv2022

Multiwavelength search for the origin of IceCube's neutrinos

The origin of astrophysical high-energy neutrinos detected by the IceCube Neutrino Observatory remains a mystery to be solved. In this paper we search for neutrino source candidates within the $90$% containment area of $70$ track-type neutrino events recorded by the IceCube Neutrino Observatory. By employing the Fermi-LAT 4FGL-DR2, the Swift-XRT 2SXPS and the CRATES catalogs, we identify possible gamma, X-ray and flat-spectrum radio candidate sources of track-type neutrinos. We find that based on the brightness of sources and their spatial correlation with the track-type IceCube neutrinos, the constructed neutrino samples represent special populations of sources taken from the full Fermi-LAT 4FGL-DR2/Swift-XRT 2SXPS/CRATES catalogs with similar significance ($2.1σ$, $1.2σ$, $2σ$ at $4.8~\mathrm{GHz}$, $2.1σ$ at $8.4~\mathrm{GHz}$, respectively, assuming 50% astrophysical signalness). After collecting redshifts and deriving sub-samples of the CRATES catalog complete in the redshift--luminosity plane, we find that the 4.8 GHz ($8.4$~GHz) sub-sample can explain between 4% and 53% ($3$% and $42$%) of the neutrinos (90% C.L.), when the probability to detect a neutrino is proportional to the ($k$-corrected) radio flux. The overfluctuations indicate that a part of the sample is likely to contribute and that more sophisticated schemes in the source catalog selection are necessary to identify the neutrino sources at the $5σ$ level. Our selection serves as a starting point to further select the correct sources.

astro-ph.HE↗

arXiv2021

Cosmic neutrinos from temporarily gamma-suppressed blazars

Despite the uncovered association of a high-energy neutrino with the apparent flaring state of blazar TXS 0506+056 in 2017, the mechanisms leading to astrophysical particle acceleration and neutrino production are still uncertain. Recent studies found that when transparent to $γ$-rays, $γ$-flaring blazars do not have the opacity for protons to produce neutrinos. Here we present observational evidence for an alternative explanation, in which $γ$-ray emission is suppressed during efficient neutrino production. A large proton and target photon density help produce neutrinos while temporarily suppress the observable $γ$-emission due to a large $γγ$ opacity. We show that the Fermi-LAT $γ$-flux of blazar PKS 1502+106 was at a local minimum when IceCube recorded the coincident high-energy neutrino IC-190730A. Using data from the OVRO 40-meter Telescope, we find that radio emission from PKS 1502+106 at the time period of the coincident neutrino IC-190730A was in a high state, in contrast to earlier time periods when radio and $γ$ fluxes are correlated for both low and high states. This points to an active outflow that is $γ$-suppressed at the time of neutrino production. We find similar local $γ$-suppression in other blazars, including in MAGIC's TeV flux of TXS\,0506+056 and Fermi-LAT's flux of blazar PKS B1424-418 at the time of coincident IceCube neutrino detections. Using temporary $γ$-suppression, neutrino-blazar coincidence searches could be substantially more sensitive than previously assumed, enabling the identification of the origin of IceCube's diffuse neutrino flux possibly with already existing data.

astro-ph.HE↗

arXiv2018

Radio background and IGM heating due to Pop III supernovae explosions

We consider the synchrotron emission from high energy electrons accelerated in supernova explosions of massive Population III stars in high redshift minihaloes of mass $10^{5\hbox {--}7} \rm M_\odot$. We show the resulting intensity of radio background from this process can be substantial, which could potentially explain the recently reported EDGES result, if not for the associated heating of the IGM by CR protons which are also produced at the same time. The trade-off between the radio background and heating is such that the 21 cm brightness temperature cannot be larger than $\vert ΔT_{21}\vert \sim 0.25$ K. The radio background and heating are both produced by energetic particles, although one by energetic electrons and the other by energetic protons. The two competing processes, production of radio background and heating of IGM by Pop III supernovae, determine the depth of the trough in the 21 cm brightness temperature which can be observed in future experiments and used as a test of this scenario.

astro-ph.HE↗

arXiv2016

An alternative Explanation for the Fermi GeV Gamma-Ray Excess

The "GeV-excess" of the diffuse gamma-rays in the halo is studied with a template fit based on energy spectra for each possible process of gamma-ray emission. Such a fit allows to determine the background and signal simultaneously, so the Galactic Disk can be included in the analysis. We find evidence that the "excess", characterised by a gamma-ray spectrum peaking at 2 GeV, is much stronger in Molecular Clouds in the disk than the "GeV-excess" observed up to now in the halo. The possible reason why the emissivity of Molecular Clouds peaks at 2 GeV are the energy losses and magnetic cutoffs inside MCs, thus depleting the low energy part of the CR spectra and shifting the maximum of the gamma-ray spectra to higher energies. This peaking of the emissivity in Molecular Clouds at 2 GeV was clearly observed from the spectrum of the Central Molecular Zone, which dominates the emission in the inner few degrees of the Galactic Centre. Although the spectrum of the Central Molecular Zone peaks at 2 GeV, it cannot be responsible for the "GeV-excess" observed in the halo, since the latitude extension of the Zone is below $\rm |b|<0.5^\circ$. However, lines-of-sight into the halo cross Molecular Clouds in the disk, so the emissivity of clouds in the disk will be observed in the halo as an apparent "GeV-excess". The fact, that this "GeV-excess" has the same morphology in the disk {\it and} in the halo as the column density of Molecular Clouds, as traced by the CO map from the Planck satellite resembling an NFW-like latitude profile, and the fact the MCs have an emissivity peaking at 2 GeV shows that the "GeV-excess" originates from Molecular Clouds in the disk, not from a process surrounding the Galactic Centre.

astro-ph.HE↗

arXiv2016

The Nature and Origin of Ultra-High Energy Cosmic Ray Particles

We outline two concepts to explain Ultra High Energy Cosmic Rays (UHECRs), one based on radio galaxies and their relativistic jets and terminal hot spots, and one based on relativistic Super-Novae (SNe) or Gamma Ray Bursts (GRBs) in starburst galaxies, one matching the arrival direction data in the South (the radio galaxy Cen A) and one in the North (the starburst galaxy M82). Ubiquitous neutrino emission follows accompanied by compact TeV photon emission, detectable more easily if the direction is towards Earth. The ejection of UHECRs is last. We have observed particles up to ZeV, neutrinos up to PeV, photons up to TeV, 30 - 300 Hz GW events, and hope to detect soon of order Hz to mHz GW events. Energy turnover in single low frequency GW events may be of order 10^63 erg. How can we further test these concepts? First of all by associating individual UHECR events, or directional groups of events, with chemical composition in both the Telescope Array (TA) Coll. and the Auger Coll. data. Second by identifying more TeV to PeV neutrinos with recent SMBH mergers. Third by detecting the order < mHz GW events of SMBH binaries, and identifying the galaxies host to the stellar BH mergers and their GW events in the range up to 300 Hz. Fourth by finally detecting the formation of the first generation of SMBHs and their mergers, surely a spectacular discovery.

astro-ph.HE↗

arXiv2015

Cosmic rays: the spectrum and chemical composition from $10^{10}$ to $10^{20}$ eV

The production of energetic particles in the universe remains one of the great mysteries of modern science. The mechanisms of acceleration in astrophysical sources and the details about the propagation through the galactic and extragalactic media are still to be defined. In recent years, the cosmic ray flux has been measured with high precision in the energy range from \energy{10} to \energyEV{20.5} by several experiments using different techniques. In some energy ranges, it has been possible to determine the flux of individual elements (hydrogen to iron nuclei). This paper explores an astrophysical scenario in which only our Galaxy and the radio galaxy Cen A produce all particles measured on Earth in the energy range from \energy{10} to \energyEV{20.5}. Data from AMS-02, CREAM, KASCADE, KASCADE-Grande and the Pierre Auger Observatories are considered. The model developed here is able to describe the total and individual particle flux of all experiments considered. It is shown that the theory used here is able to describe the smooth transition from space-based to ground-based measurements. The flux of each element as determined by KASCADE and KASCADE-Grande and the mass sensitivity parameter \xmax measured by the Pierre Auger Observatory above \energyEV{18} are also explored within the framework of the model. The transition from \energy{16} to \energyEV{18} is carefully analyzed. It is shown that the data measured in this energy range suggest the existence of an extra component of cosmic rays yet to be understood.

astro-ph.HE↗

arXiv2014

Cosmic backgrounds due to the formation of the first generation of supermassive black holes

The statistics of black holes and their masses strongly suggests that their mass distribution has a cutoff towards lower masses near $3 \times 10^{6}$ M$_{\odot}$. This is consistent with a classical formation mechanism from the agglomeration of the first massive stars in the universe. However, when the masses of the stars approach $10^{6}$ M$_{\odot}$, the stars become unstable and collapse, possibly forming the first generation of cosmological black holes. Here we speculate that the claimed detection of an isotropic radio background may constitute evidence of the formation of these first supermassive black holes, since their data are compatible in spectrum and intensity with synchrotron emission from the remnants. The model proposed fulfills all observational conditions for the background, in terms of single-source strength, number of sources, far-infrared and gamma-ray emission. The observed high energy neutrino flux is consistent with our calculations in flux and spectrum. The proposal described in this paper may also explain the early formation and growth of massive bulge-less disk galaxies as derived from the massive, gaseous shell formed during the explosion prior to the formation of a supermassive black hole.

astro-ph.CO↗

arXiv2014

Dark energy as stimulated emission of gravitons from a background brane

The idea that dark energy is gravitational waves may explain its strength and its time-evolution provided that the additional energy comes from a background. A possible concept is that dark energy is the ensemble of coherent bursts (solitons) of gravitational waves originally produced by stimulated emission when the first generation of super-massive black holes was formed. These solitons get their initial energy as well as keep up their energy density throughout the evolution of the universe by stimulating emission from a background brane. We model this process by working out this energy transfer in a Boltzmann equation approach. The transit of these gravitational wave solitons may be detectable. Key tests include pulsar timing, clock jitter and the radio and neutrino backgrounds.

astro-ph.CO↗

arXiv2013

The Galactic Wind Haze and its $γ$-spectrum

We study the possibility that the gamma ray emission in the Fermi bubbles observed is produced by cosmic ray electrons with a spectrum similar to Galactic cosmic rays. We argue that the cosmic ray electrons steepen near 1 TeV from $E^{-3}$ to about $E^{-4.2}$, and are partially secondaries derived from the knee-feature of normal cosmic rays. We speculate that the observed feature at $\sim 130$ GeV could essentially be due to inverse Compton emission off a pair-production peak on top of a turn-off in the $γ$ ray spectrum at $\sim 130$ GeV. It suggests that the knee of normal cosmic rays is the same everywhere in the Galaxy. A consequence could be that all supernovae contributing give the same cosmic ray spectrum, with the knee feature given by common stellar properties; in fact, this is consistent with the supernova theory proposed by Bisnovatyi-Kogan (1970), a magneto-rotational mechanism, if massive stars converge to common properties in terms of rotation and magnetic fields just before they explode.

astro-ph.HE↗

arXiv2013

Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A

Observations of the FR I radio galaxy Centaurus A in radio, X-ray and gamma-ray bands provide evidence for lepton acceleration up to several TeV and clues about hadron acceleration to tens of EeV. Synthesising the available observational constraints on the physical conditions and particle content in the jets, inner lobes and giant lobes of Centaurus A, we aim to evaluate its feasibility as an ultra-high-energy cosmic-ray source. We apply several methods of determining jet power and affirm the consistency of various power estimates of ~ 1 x 10^43 erg s^-1. Employing scaling relations based on previous results for 3C 31, we estimate particle number densities in the jets, encompassing available radio through X-ray observations. Our model is compatible with the jets ingesting ~ 3 x 10^21 g s^-1 of matter via external entrainment from hot gas and ~ 7 x 10^22 g s^-1 via internal entrainment from jet-contained stars. This leads to an imbalance between the internal lobe pressure available from radiating particles and magnetic field, and our derived external pressure. Based on knowledge of the external environments of other FR I sources, we estimate the thermal pressure in the giant lobes as 1.5 x 10^-12 dyn cm^-2, from which we deduce a lower limit to the temperature of ~ 1.6 x 10^8 K. Using dynamical and buoyancy arguments, we infer ~ 440-645 Myr and ~ 560 Myr as the sound-crossing and buoyancy ages of the giant lobes respectively, inconsistent with their spectral ages. We re-investigate the feasibility of particle acceleration via stochastic processes in the lobes, placing new constraints on the energetics and on turbulent input to the lobes. The same 'very hot' temperatures that allow self-consistency between the entrainment calculations and the missing pressure also allow stochastic UHECR acceleration models to work.

astro-ph.HE↗