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Recently, arXiv:2210.05659 shows that a photon-axion like particle (ALP) oscillation can boost the survival rate of the high energy photons associated with the observed GRB221009A event. Here, we show that the proposed ALP is consistent with the electroweak axion with an anomaly free $Z_{10}$ Froggatt-Nielsen symmetry., Comment: 2 pages, 1 figure; comments are welcome!

To further shed light on whether pre-recombination models can resolve the Hubble tension, we explore constraints on the cosmic background evolution that are insensitive to early-universe physics. The analysis of the cosmic microwave background (CMB) anisotropy has been thought to highly rely on early-universe physics. However, we show that the fact that the sound horizon at recombination being close to that at the end of the drag epoch is insensitive to early-universe physics. This allows us to link the absolute sizes of the two horizons and treat them as free parameters. Jointly, the CMB peak angular size, Baryon Acoustic Oscillations (BAO), and Type Ia supernovae can be used as "early-universe-physics insensitive and uncalibrated cosmic standards", which measure the cosmic history from recombination to today. They can set strong and robust constraints on the post-recombination cosmic background, especially the matter density parameter with $��_{\rm{m}}=0.302\pm0.008$ ($68\%$ C.L.) assuming a flat $��$CDM after recombination. When we combine these with other non-local observations, we obtain several constraints on $H_0$ with significantly reduced sensitivity to early-universe physics. These are all more consistent with the Planck 2018 result than the local measurement results such as those based on Cepheids. This suggests a tension between the post-recombination, but non-local, observations and the local measurements which cannot be resolved by modifying pre-recombination early universe physics., Results updated with stellar-age constraints; conclusion unchanged. Accepted for publication in ApJ

In this paper, a fine particle matter (PM) sensor has been designed, built up, and measured. It consists of a LED, a photodiode, a glass air channel and collimated structure, as show in Fig.1. Compared with the conventional fine PM sensors [1-2], this sensor has higher sensitivity and better reliability via immunity to particle contamination. A simulation model of the particle matter sensor is built based on the right angle Mie-scattering theory [3]. The simulation results are shown in Fig 2. In the simulation, the wavelength of LED is 650 nm, and particles diameter is 1 μm. The particles are guided into a “U” shape glass channel with a good light transparence at visible light region. And the light is collimated by an embedded lens in LED packaging, and injected into the glass channel with the minimum scattering from the glass channel. The particles are isolated by the glass channel so that they cannot contaminate the LED and the photodiode, which is a common failure mode in conventional PM sensors. Based on the simulation and fitting process, the detection limitation is down to around 0.2 μg/m3 when the power of the light source is 0.4mW and specific detectivity of the photodiode is 0.017uW. The sensor used in characterization is assembled as shown in Fig. 3. A TSI 9306 six-jet atomizer is used to generate fine particles (diameter ~ 1 m) carried by dry-air gas flow. A reference PM detector (model: TSI 8520 DustTrak Aerosol Monitor) is connected at the outlet of the sensor to monitor the particle mass concentration in real-time. The glass channel with gold coating is used to guide the particle air. The experimental results are shown in Fig. 4. The blue dots and red line are the testing and fitting results, respectively. Through analysis, the relationship between particle mass concentration and PD voltage can match to linear trend. The output signal is up to approximate 1.5 μV when the PM concentration changes 1μg/m3, and the detection limitation is around 3.3ug/m3, which is much better than the value of 10μg/m3 of the conventional PM sensors.