High-energy electromagnetic, neutrino, and cosmic-ray emission by stellar-mass black holes in disks of active galactic nuclei

Some Seyfert galaxies are detected in high-energy gamma rays, but the mechanism and site of gamma-ray emission are unknown. Also, the origins of the cosmic high-energy neutrino and MeV gamma-ray backgrounds have been veiled in mystery since their discoveries. We propose emission from stellar-mass BHs (sBHs) embedded in disks of active galactic nuclei (AGN) as their possible sources. These sBHs are predicted to launch jets due to the Blandford-Znajek mechanism, which can produce intense electromagnetic, neutrino, and cosmic-ray emissions. We investigate whether these emissions can be the sources of cosmic high-energy particles. We find that emission from internal shocks in the jets can explain gamma rays from nearby radio-quiet Seyfert galaxies including NGC1068, if the Lorentz factor of the jets ($\Gamma_{\rm j}$) is high. On the other hand, for moderate $\Gamma_{\rm j}$, the emission can significantly contribute to the background gamma-ray and neutrino intensities in the $\sim {\rm MeV}$ and $\lesssim {\rm PeV}$ bands, respectively. Furthermore, for moderate $\Gamma_{\rm j}$ with efficient amplification of the magnetic field and cosmic-ray acceleration, the neutrino emission from NGC1068 and the ultrahigh-energy cosmic rays can be explained. These results suggest that the neutrino flux from NGC1068 as well as the background intensities of ${\rm MeV}$ gamma rays, neutrinos, and the ultrahigh-energy cosmic rays can be explained by a unified model. Future MeV gamma-ray satellites will test our scenario for neutrino emission.Comment: 14 pages, 8 figures, accepted in Ap

One parameter generalization of BW inequality and its application to open quantum dynamics

In this paper, we introduce a one parameter generalization of the famous B\"ottcher-Wenzel (BW) inequality in terms of a $q$-deformed commutator. For $n \times n$ matrices $A$ and $B$, we consider the inequality $$\Re\langle[B,A],[B,A]_q\rangle \le c(q) \|A\|^2 \|B\|^2,$$ where $\langle A,B \rangle = {\rm tr}(A^*B)$ is the Hilbert-Schmidt inner product, $\|A\|$ is the Frobenius norm, $[A,B] =AB-BA$ is the commutator, and $[A,B]_q =AB-qBA$ is the $q$-deformed commutator. We prove that when $n=2$, or when $A$ is normal with any size $n$, the optimal bound is given by $$c(q) = \frac{(1+q) +\sqrt{2(1+q^2)}}{2}.$$ We conjecture that this is also true for any matrices, and this conjecture is perfectly supported for $n$ up to $15$ by numerical optimization. When $q=1$, this inequality is exactly BW inequality. When $q=0$, this inequality leads the sharp bound for the $r$-function which is recently derived for the application to universal constraints of relaxation rates in open quantum dynamics.Comment: 11 page

Relation between the Dynamics of the Reduced Purity and Correlations

A general property of the relation between the dynamics of the reduced purity and correlations is investigated in quantum mechanical systems. We show that a non-zero time-derivative of the reduced purity of a system implies the existence of non-zero correlations with its environment under any unbounded Hamiltonians with finite variance. This shows the role of local dynamical information on the correlations, as well as the role of correlations in the mechanism of purity change.Comment: 7 page

Indirect reciprocity is sensitive to costs of information transfer

How natural selection can promote cooperative or altruistic behavior is a fundamental question in biological and social sciences. One of the persuasive mechanisms is "indirect reciprocity," working through reputation: cooperative behavior can prevail because the behavior builds the donor's good reputation and then s/he receives some reciprocal benefits from someone else in the community. However, an important piece missed in the previous studies is that the reputation-building process requires substantial cognitive abilities such as communication skills, potentially causing a loss of biological fitness. Here, by mathematical analyses and individual-based computer simulations, we show that natural selection never favors indirect reciprocal cooperation in the presence of the cost of reputation building, regardless of the cost-to-benefit ratio of cooperation or moral assessment rules (social norms). Our results highlight the importance of considering the cost of high-level cognitive abilities in studies of the evolution of humans' and animals' social behavior

Shock cooling and breakout emission for optical flares associated with gravitational wave events

The astrophysical origin of stellar-mass black hole (BH) mergers discovered through gravitational waves (GWs) is widely debated. Mergers in the disks of active galactic nuclei (AGN) represent promising environments for at least a fraction of these events, with possible observational clues in the GW data. An additional clue to unveil AGN merger environments is provided by possible electromagnetic emission from post-merger accreting BHs. Associated with BH mergers in AGN disks, emission from shocks emerging around jets launched by accreting merger remnants is expected. In this paper we compute the properties of the emission produced during breakout and the subsequent adiabatic expansion phase of the shocks, and we then apply this model to optical flares suggested to be possibly associated with GW events. We find that the majority of the reported flares can be explained by the breakout and the shock cooling emission. If these events are real, then the merging locations of binaries are constrained depending on the emission processes. If the optical flares are produced by shock cooling emission, they would display moderate color evolution, possibly color variations among different events, a positive correlation between the delay time and the duration of flares, and accompanying breakout emission in X-ray bands before the optical flares. If the breakout emission dominates the observed lightcurve, it is expected that the color is distributed in a narrow range in the optical band, and the delay time from GW to electromagnetic emission is longer than $\sim 2$ days. Hence, further explorations of the distributions of delay times, color evolution of the flares, and associated X-ray emission will be useful to test the proposed emission model for the observed flares.Comment: 15 pages, 3 figure

Observable signatures of stellar-mass black holes in active galactic nuclei

Stellar-mass black holes (BHs) are predicted to be embedded in the disks of active galactic nuclei (AGN) due to gravitational drag and in-situ star formation. However, clear evidence for AGN disk-embedded BHs is currently lacking. Here, as possible electromagnetic signatures of these BHs, we investigate breakout emission from shocks emerging around Blandford-Znajek jets launched from accreting BHs in AGN disks. We assume that the majority of the highly super-Eddington flow reaches the BH, produces a strong jet, and the jet produces feedback that shuts off accretion and thus leads to episodic flaring. While these assumptions are highly uncertain at present, they predict a breakout emission characterized by luminous thermal emission in the X-ray bands, and bright, broadband non-thermal emission from the infrared to the gamma-ray bands. The flare duration depends on the BH's distance $r$ from the central supermassive BH, varying between $10^3-10^6$ s for $r \sim 0.01-1$ pc. This emission can be discovered by current and future infrared, optical, and X-ray wide-field surveys and monitoring campaigns of nearby AGNs.Comment: 10 pages, 4 figures, accepted in ApJ

Exploration of factors affecting webcam-based automated gaze coding

The version of record of this article, first published in Behavior Research Methods, is available online at Publisher’s website: https://doi.org/10.3758/s13428-024-02424-1.Online experiments have been transforming the field of behavioral research, enabling researchers to increase sample sizes, access diverse populations, lower the costs of data collection, and promote reproducibility. The field of developmental psychology increasingly exploits such online testing approaches. Since infants cannot give explicit behavioral responses, one key outcome measure is infants’ gaze behavior. In the absence of automated eyetrackers in participants’ homes, automatic gaze classification from webcam data would make it possible to avoid painstaking manual coding. However, the lack of a controlled experimental environment may lead to various noise factors impeding automatic face detection or gaze classification. We created an adult webcam dataset that systematically reproduced noise factors from infant webcam studies which might affect automated gaze coding accuracy. We varied participants’ left-right offset, distance to the camera, facial rotation, and the direction of the lighting source. Running two state-of-the-art classification algorithms (iCatcher+ and OWLET) revealed that facial detection performance was particularly affected by the lighting source, while gaze coding accuracy was consistently affected by the distance to the camera and lighting source. Morphing participants’ faces to be unidentifiable did not generally affect the results, suggesting facial anonymization could be used when making online video data publicly available, for purposes of further study and transparency. Our findings will guide improving study design for infant and adult participants during online experiments. Moreover, training algorithms using our dataset will allow researchers to improve robustness and allow developmental psychologists to leverage online testing more efficiently