# The LHAASO PeVatron Bright Sky: What We Learned
## 3 Overview of the 12 LHAASO Sources
### LHAASO J2032+4102  
LHAASO J2032+4102 has the highest maximum energy among the 12 PeVatron candidates: 1.4 PeV. Similarly to LHAASO J2018+3651 and (the next) LHAASO J2108+5157, this is located in the Cygnus region, and there are several potential TeV counterpart candidates: TeV J2032+4130/2 HWC J2031+415/VER J2032+414, ARGO J2031+4157, and MGRO J2031+41 (see Figure 14).  
The first source, TeV J2032+4130/2 HWC J2031+415/VER J2032+414, was first detected at TeV energies by HEGRA [100] and then by HAWC [117] and VERITAS [191]. It is associated with the PWN of the PSR J2032+412 and overlaps with one of the nine sources of the first HAWC catalog, emitting at E \(>\) 56 TeV [131]. According to [118], it is a TeV halo candidate, because it is associated with a pulsar \(>\)100 kyrs and has a TeV halo expected-flux at least as large as 2% of the Geminga flux. However, no other analyses have confirmed (or ruled out) this hypothesis. According the graph produced in that work [26] (see Figure 5), LHAASO J2032+4102 is one of two (the other is LHAASO J2108+5157, which has PSR in its surroundings) LHAASO candidate PeVatrons that cannot be explained by an associated pulsar; it lies above the absolute maximum electron energy producible by a PSR limited by radiative losses or a potential drop (see Section 2.3). This important work indicated that we need to find other sources for the origin of the UHE LHAASO emission detected from this region.  
In this context, an important candidate is ARGO J2031+4157, which is the TeV counterpart of the Cygnus Cocoon [131], which was detected for the first time at GeV energies by Fermi-LAT [101] and then confirmed at E \(>\) 100 TeV by HAWC [103] and Tibet AS\({}_{\gamma}\)[104]. In [192], the authors tried to explain the entire GeV-TeV spectrum of the Cygnus Cocoon  
Figure 13: LHAASO J2018+3651. (**Left**): HAWC significance map of the region of interest, with the addition of the LHAASO centroid (Figure from [189]). (**Right**): SED of the PWN G75.2+0.1, where the leptonic model can perfectly explain the multiwavelength spectrum from this source (Figure from [190], reproduced with permission from [190], Elsevier, 2023.).  
with a model based on [19]: particle acceleration and propagation in a superbubble with multiple shocks of different strengths produced by the powerful winds of massive stars and supernovae. Their model well explains the Fermi-LAT, ARGO, and HAWC data, but it does not fit only one LHAASO spectral point. However, it can also explain the behavior of the \(\gamma\)-ray spectrum from Westerlund 2, suggesting that this model can work with MSCs, and questioning the association of the LHAASO spectral point with Cygnus Cocoon. Further and deeper analyses are needed to confirm this conclusion.  
In [193], with a simpler acceleration model without assumptions about propagation, the authors explained the multiwavelength spectrum of the Cygnus region using a lepto-hadronic scenario (see Figure 14, right), also estimating a neutrino flux in agreement with an IceCube neutrino (see Figure 4 of [193], right). The Cygnus Cocoon, indeed, could be the only galactic source with evidence of neutrino emission (IceCube-201120A, at the IceCube sensitivity limit, not confirmed), coincident with a \(\gamma\)-ray excess detected by the Carpet-2 experiment [194]. If this neutrino event was correlated with the Cocoon, also taking into account the UHE LHAASO photons, this could be a hint that this source may, not only be a confirmed LHAASO PeVatron, but also a hadronic one.  
The last possible TeV counterpart, MGRO J2031+41, was identified with TeV J2032+4130, but Milagro speculated that its emission could be due to more than one source and, consequently, it is listed separately in the TeVCat [131].