arXiv subjects

Tian-Qi Huang

Publications and source records attributed to Tian-Qi Huang.

9 recordsLinked to original sources

arXiv2025

Ultrahigh-Energy Gamma-ray Emission Associated with Black Hole-Jet Systems

Black holes (BH), one of the most intriguing objects in the universe, can manifest themselves through electromagnetic radiation initiated by the accretion flow. Some stellar-mass BHs drive relativistic jets when accreting matter from their companion stars, forming microquasars. Non-thermal emission from the radio to tera-electronvolt (TeV) gamma-ray band has been observed from microquasars, indicating the acceleration of relativistic particles. Here we report detection of four microquasars (SS 433, V4641 Sgr, GRS 1915+105, MAXI J1820+070) of spectrum extending to the ultrahigh-energy (UHE; photon energy $E>100$ TeV) band and one microquasar (Cygnus X-1) of spectrum approaching 100 TeV, using the Large High Altitude Air Shower Observatory (LHAASO). Notably, the total emission associated with SS 433 cannot be interpreted with a single leptonic component. In the UHE band, its emission is in spatial coincidence with a giant atomic cloud, which is consistent with a hadronic origin. An elongated source is discovered from V4641 Sgr with the spectrum continuing up to 800 TeV. The detection of UHE gamma rays demonstrates that accreting BHs and their environments can operate as extremely efficient accelerators of particles out of 1 peta-electronvolt (PeV), suggesting microquasars to be important contributors to Galactic cosmic rays especially around the `knee' region.

astro-ph.HE↗

arXiv2025

A Giant Peanut-shaped Ultra-High-Energy Gamma-Ray Emitter Off the Galactic Plane

Ultra-high-energy (UHE), exceeding 100 TeV (10^12 electronvolts), γ-rays manifests extreme particle acceleration in astrophysical sources. Recent observations by γ-ray telescopes, particularly by the Large High Altitude Air Shower Observatory (LHAASO), have revealed a few tens of UHE sources, indicating numerous Galactic sources capable of accelerating particles to PeV (10^15 electronvolts) energies. However, discerning the dominant acceleration mechanisms (leptonic versus hadronic), the relative contributions of specific source classes, and the role of particle transport in shaping their observed emission are central goals of modern UHE astrophysics. Here we report the discovery of a giant UHE γ-ray emitter at -17.5° off the Galactic plane - a region where UHE γ-ray sources are rarely found. The emitter exhibits a distinctive asymmetric shape, resembling a giant "Peanut" spanning 0.45° \times 4.6°, indicative of anisotropic particle distribution over a large area. A highly aged millisecond pulsar (MSP) J0218+4232 is the sole candidate accelerator positionally coincident with the Peanut region. Its association with UHE γ-rays extending to 0.7 PeV, if confirmed, would provide the first evidence of a millisecond pulsar powering PeV particles. Such a finding challenges prevailing models, which posit that millisecond pulsars cannot sustain acceleration to PeV energies. The detection reveals fundamental gaps in understanding particle acceleration, cosmic-ray transport, and interstellar magnetic field effects, potentially revealing new PeV accelerator (PeVatron) classes.

astro-ph.HE↗

arXiv2025

Cosmogenic Neutrino Point Source and KM3-230213A

Cosmogenic neutrinos (CNs) are produced by ultra-high energy cosmic rays (UHECRs) interacting with cosmic background radiation. We investigated the properties of CN point/extended sources, i.e, the neutrino spectrum, and angular profile as functions of time, by assuming that UHECR sources are transient events, such as gamma-ray bursts. The properties depend much on the intergalactic magnetic field (IGMF), but the angular extent is in general sub-degree, within which the CN flux can overshoot the diffuse CN flux in early time. The nearby CN point sources could be detected for the low IGMF case by future neutrino telescopes. The recent KM3-230213A event is possible to account for by a nearby transient CN source, rather than diffuse CN emission. Observations of CN point sources will provide a chance to search for UHECR sources.

astro-ph.HE↗

arXiv2025

Search for neutrino emission from the Cygnus Bubble based on LHAASO $γ$-ray observations

The Cygnus region, which contains massive molecular and atomic clouds and young stars, is a promising Galactic neutrino source candidate. Cosmic rays transport in the region can produce neutrinos and $γ$-rays. Recently, the Large High Altitude Air Shower Observatory (LHAASO) detected an ultrahigh-energy $γ$-ray bubble (Cygnus Bubble) in this region. Using publicly available track events detected by the IceCube Neutrino Observatory in 7 years of full detector operation, we conduct searches for correlated neutrino signals from the Cygnus Bubble with neutrino emission templates based on LHAASO $γ$-ray observations. No significant signals were found for any employed templates. With the 7 TeV $γ$-ray flux template, we set a flux upper limit of 90% confidence level (C.L.) for the neutrino emission from the Cygnus Bubble to be $5.7\times10^{-13}\, \mathrm{TeV}^{-1}\mathrm{cm}^{-2}\mathrm{s}^{-1}$ at 5 TeV.

astro-ph.HE↗

arXiv2025

Search for neutrino signals correlated with LHAASO diffuse Galactic emission

The diffuse Galactic $γ$-ray emission originates from the interactions between cosmic rays and the interstellar medium or radiation fields within our Galaxy, where the production of neutrinos is also anticipated. Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported measurements of diffuse $γ$-rays from the Galactic plane with energies ranging from sub-TeV to 1 PeV. Using publicly available 7 years of IceCube track data with the full detector, we conduct a template search using the $γ$-ray flux map observed by LHAASO-KM2A as the neutrino emission template and perform a scan search of the Galactic plane. In the template search, a mild excess of neutrinos is observed in the Galactic plane with a pretrial (posttrial) significance of $1.9σ$ ($1.1σ$). The measured muon neutrino intensity at 25 TeV is $4.73^{+2.53}_{-2.51}\times10^{-14}\,{\rm TeV^{-1}\,cm^{-2}\,s^{-1}\,sr^{-1}}$, consistent with the expected neutrino flux assuming that all the diffuse Galactic $γ$-rays originate from hadronic interactions. In the Galactic plane scan search, the most significant location is found at $l=63.57^{\circ}$ and $b=0.93^{\circ}$ with a pretrial (posttrial) significance of $4.6σ$ ($1.8σ$).

astro-ph.HE↗

arXiv2023

Determining the Origin of Very-high-energy Gamma Rays from Galactic Sources by Future Neutrino Observations

Recently, the Large High Altitude Air Shower Observatory (LHAASO) identified 12 $γ$-ray sources emitting gamma rays with energies above 100 TeV, making them potential PeV cosmic-ray accelerators (PeVatrons). Neutrino observations are crucial in determining whether the gamma-ray radiation process is of hadronic or leptonic origin. In this paper, we study three detected sources, LHAASO J1908+0621, LHAASO J2018+3651, and LHAASO J2032+4102, which are also the most promising galactic high-energy neutrino candidate sources with the lowest pre-trial p-value based on the stacking searches testing for excess neutrino emission by IceCube Neutrino Observatory. We study the lepto-hadronic scenario for the observed multiband spectra of these LHAASO sources considering the possible counterpart source of the LHAASO sources. The very-high-energy gamma rays are entirely attributed to the hadronic contribution, therefore the most optimistic neutrino flux can be derived. Then, we evaluate the statistical significance (p-value) as a function of the observation time of IceCube and the next-generation IceCube-Gen2 neutrino observatory respectively. Our results tend to disfavor that all gamma rays above $100\,\rm GeV$ from LHAASO J1908+0621 are of purely hadronic origin based on current IceCube observations, but the purely hadronic origin of gamma rays above $100\,\rm TeV$ is still possible. By IceCube-Gen2, the origin of gamma rays above $100\,\rm TeV$ from LHAASO J1908+0621 can be further determined at a $5σ$ significance level within a running time of $\sim 3$ years. For LHAASO J2018+3651 and LHAASO J2032+4102, the required running time of IceCube-Gen2 is $\sim 10$ years ($3σ$) and $\sim 10$ years ($5σ$), respectively. Future observations by the next-generation neutrino telescope will be crucial to understanding the particle acceleration and radiation processes inside the sources.

astro-ph.HE↗

arXiv2022

Neutrino Observations of LHAASO Sources: Present Constraints and Future Prospects

The Large High Altitude Air Shower Observatory (LHAASO) observed a dozen of gamma-ray sources with significant emission above 100 TeV, which may be strong candidates of PeVatrons. Neutrino observations are crucial to diagnose whether the gamma-ray radiative process is hadronic or leptonic. We use the Bayesian method to analyze the ten-year (2008-2018) IceCube data, and hence constrain the hadronic gamma-ray emission in the LHAASO sources. The present neutrino data show that the hadronic gamma-ray flux from Crab Nebula is lower than the observed gamma-ray flux at the 90% C.L. and contributes less than 86%, which disfavors the hadronic origin of the gamma-rays below tens of TeV. For the other LHAASO sources, the present neutrino observations cannot put useful constraints on the gamma-ray radiative process. We consider the uncertainty of the source extension: the upper limits on hadronic gamma-ray flux tend to increase with the extension; and some sources, i.e., LHAASO J2032+4102, LHAASO J1929+1745, and LHAASO J1908+0621, show relatively high statistical significance of neutrino signals if the extension is <0.6 deg. We finally estimate the future observational results of LHAASO sources by the proposed neutrino telescopes. If the LHAASO-observed PeV gamma-rays are of hadronic origin, Crab Nebula may be detected at >100 TeV at 3-sigma C.L. within 20 years by a neutrino detector with the effective area 30 times that of IceCube.

astro-ph.HE↗

arXiv2021

Constraints on Hadronic Contribution to LHAASO Sources with Neutrino Observations

LHAASO detected 12 gamma-ray sources above 100 TeV which are the possible origins of Galactic cosmic-rays. We summarize the neutrino measurements by IceCube and ANTARES in the vicinity of LHAASO sources to constrain the contribution of hadronic gamma-rays in these sources. We find that the current observations constrain that the hadronic gamma-rays contribute no more than ~60% of the gamma-rays from Crab Nebula. Gamma-rays from two LHAASO sources, LHAASO J1825-1326 and LHAASO J1907+0626, are dominated by leptonic components up to ~200 TeV, under the hypotheses in the analysis by IceCube. The uncertainties of the constraint on the hadronic gamma-ray emission are discussed. We also constrain the total 100 TeV gamma-ray emission from TeV PWNe relying on the remarkable sensitivity of LHAASO at that energies.

astro-ph.HE↗

arXiv2019

Transient High-energy Gamma-rays and Neutrinos from Nearby Type II Supernovae

The dense wind environment (or circumstellar medium) may be ubiquitous for the regular Type II supernovae (SNe) before the explosion, the interaction of which with the SN ejecta could result in a wind breakout event. The shock generated by the interaction of the SN ejecta and the wind can accelerate the protons and subsequently the high-energy gamma-rays and neutrinos could arise from the inelastic pp collisions. In this work, we present the detailed calculations of gamma-ray and neutrino production for the regular Type II SNe. The calculation is executed by applying time-dependent evolutions of dynamic and proton distribution so that the emission could be shown at different times. Our results show, for the SN 2013fs-like wind environment, the multi-GeV and ~ few-100 TeV gamma-rays are detectable with a time window of several days at <~ 2-3 Mpc by Fermi/LAT and CTA during the ejecta-wind interaction, respectively, and can be detected at a further distance if the wind environment is denser. Besides, we found the contribution of the wind breakouts of regular Type II SNe to diffuse neutrino flux is subdominant by assuming all Type II SNe are SN 2013fs-like, whereas for a denser wind environment the contribution could be conspicuous above 300TeV.

astro-ph.HE↗