Bosonic Dark Matter in Light of the NICER Precise Mass-Radius Measurements

We explore the presence of self-interacting bosonic dark matter (DM) within neutron stars (NSs) in light of the latest multi-messenger observations of the Neutron Star Interior Composition Explorer (NICER) and LIGO/Virgo detectors. The bosonic DM is distributed as a core inside the NS or as a halo around it leading to formation of a DM admixed NS. We focus on the variation of the visible and dark radius of the mixed object due to DM model parameters and fractions. It is shown that DM core formation reduces the visible radius and the total mass pushing them below observational limits while halo formation is in favor of the latest mass-radius observations. Moreover, we scan over the parameter space of the bosonic DM model considering two nuclear matter equation of states by applying the radius, maximum mass and tidal deformability constraints. Our investigation allows for the exclusion of a range of DM fractions, self-coupling constant and sub-GeV boson masses, which limits the amount of accumulated DM to relatively low values to be consistent with astrophysical bounds. In this paper, we introduce main features of the pulse profile corresponding to the DM admixed NS as a novel observable quantity. We find that the depth of minimum fluxes in the pulse profiles crucially depends on the amount of DM around NS and its compactness. The current/future astrophysics missions may test the possibility of the existence of DM within NSs and break the degeneracies between different scenarios via multiple observations.Comment: 24 pages, 23 figures, matches the published version in PR

A Heavy QCD Axion model in Light of Pulsar Timing Arrays

Recently, pulsar timing array (PTA) experiments reported the observation of a stochastic gravitational wave (GW) background in the nanohertz range frequency band. We show that such signal can be originated from a cosmological first-order phase transition (PT) within a well-motivated heavy (visible) QCD axion model. Considering the Peccei-Quinn symmetry breaking at the TeV scale in the scenario, we find a supercooled PT, in the parameter space of the model, prolonging the PT with the reheating temperature at the GeV scale.Comment: 7 pages, 4 figure

Investigating the Causes of Corrosion in Heat Exchanger of Waste Incinerator System of Fajr Petrochemical and Providing Suggestions for Changing the Structure of Heat Exchanger

Optimization of operational performance of heat exchanger of waste incinerator systems from the temperature point of view in order to reduce corrosion is considerably important. At Fajr Petrochemicals, equipped with a biological waste incinerator system, some difficulties have arisen including corrosion in the equipment such as the heat exchanger and filter, which is the main factor of this corrosion rests in the heat exchanger. Therefore, the modeling of heat exchanger was investigated to find the causes of condensation formation and acid production. The modeling was done based on Computational Fluid Dynamics (CFD), and it was determined that, due to entry of hot gases to the heat exchanger and instantaneous cooling of them, humidity and condensation are formed in some parts of the heat exchanger and will cause the formation of acids and corrosion in it. In this study, a developed heat exchanger model is suggested so that the cooling of hot entry gases would be done in a mild manner, and also it would be possible to have a temperature control over outlet gases from the Heat Exchanger, and after the operational construction of the suggested model, and installation of it in the system, the previous difficulties were no longer

Investigating the Causes of Corrosion in Heat Exchanger of Waste Incinerator System of Fajr Petrochemical and Providing Suggestions for Changing the Structure of Heat Exchanger

Optimization of operational performance of heat exchanger of waste incinerator systems from the temperature point of view in order to reduce corrosion is considerably important. At Fajr Petrochemicals, equipped with a biological waste incinerator system, some difficulties have arisen including corrosion in the equipment such as the heat exchanger and filter, which is the main factor of this corrosion rests in the heat exchanger. Therefore, the modeling of heat exchanger was investigated to find the causes of condensation formation and acid production. The modeling was done based on Computational Fluid Dynamics (CFD), and it was determined that, due to entry of hot gases to the heat exchanger and instantaneous cooling of them, humidity and condensation are formed in some parts of the heat exchanger and will cause the formation of acids and corrosion in it. In this study, a developed heat exchanger model is suggested so that the cooling of hot entry gases would be done in a mild manner, and also it would be possible to have a temperature control over outlet gases from the Heat Exchanger, and after the operational construction of the suggested model, and installation of it in the system, the previous difficulties were no longer

Evaluation of bacterial and fungal contamination in equipments used in ladies and gentleman barbers in Shahrekord, 2009

زمینه و هدف: عفونت های قارچی و باکتریایی از جمله بیماری های واگیردار و شایعی هستند که در همه جا یافت می شوند و آرایشگاه ها به لحاظ عمومی بودن در این میان اهمیت خاصی دارند. این مطالعه با هدف بررسی آرایشگاه های شهرکرد از نظر آلودگی های میکروبی استافیلوکوک آرئوس و قارچ های درماتوفیت انجام شد. روش بررسی: در این تحقیق توصیفی– تحلیلی داده ها از طریق تکمیل چک لیست، نمونه گیری میکروبی و قارچی و انجام تجربیات آزمایشگاهی جمع آوری و به کمک آزمون آماری کای دو تجزیه و تحلیل شد. یافته ها: استافیلوکوک آرئوس عامل 4/12 آلودگی میکروبی بود. در بین آلودگی های قارچی کمتر از 1 قارچ درماتوفیت (میکروسپوروم نانوم)، 2/8 کاندیدا آلبیکانس، 11 پنی سیلیوم، 3/3 رایزوپوس و کمتر از 1 اسکوپولاریوپسیس مشاهده گردید. بین نتایج میکروبی و نوع آرایشگاه و همچنین بین نتایج میکروبی و موقعیت محلی آرایشگاه ارتباط معنی داری وجود نداشت. نتیجه گیری: سطح آلودگی به استافیلوکوک آرئوس و قارچ های درماتوفیت در آرایشگاه های شهرکرد در مقایسه با تحقیق های انجام شده در سایر اماکن عمومی نظیر بیمارستان ها، استخرهای شنا، مجموعه های ورزشی و اتاق عمل کمتر است