Iron K alpha line of Kerr black holes with scalar hair

Recently, a family of hairy black holes in 4-dimensional Einstein gravity minimally coupled to a complex, massive scalar field was discovered [1]. Besides the mass M and spin angular momentum J, these objects are characterized by a Noether charge Q, measuring the amount of scalar hair, which is not associated to a Gauss law and cannot be measured at spatial infinity. Introducing a dimensionless scalar hair parameter q, ranging from 0 to 1, we recover (a subset of) Kerr black holes for q = 0 and a family of rotating boson stars for q = 1. In the present paper, we explore the possibility of measuring q for astrophysical black holes with current and future X-ray missions. We study the iron K alpha line expected in the reflection spectrum of such hairy black holes and we simulate observations with Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of hairy black holes, that current observations can already constrain the scalar hair parameter q, because black holes with q close to 1 would have iron lines definitively different from those we observe in the available data. We conclude that a detailed scanning of the full space of solutions, together with data from the future X-ray missions, like eXTP, will be able to put relevant constraints on the astrophysical realization of Kerr black holes with scalar hair

Artificial cooling as an alternative to increase productivity and welfare of steers under heat stress Resfriamento artificial como alternativa para aumentar o bem-estar de novilhos sob estresse térmico

The effects of a cooling system on productive efficiency and welfare of Holstein steers were evaluated during the summer. Sixty steers in the finishing phase were randomly allotted to one of two treatment-groups. Animals of control group were only provided with shade (non-cooled group) and a group of animals under a cooling system were installed in the shaded area (cooled group), which were operated daily from 09am to 6pm during the 69d of the study. The averages of environmental temperature and relative humidity were 35.4°C and 35.3%, respectively, with a temperature-humidity index average of 81.4 during the study. Individual body weight was recorded every two weeks, while body surface temperature and respiratory frequency were recorded three times per week. Blood samples were biweekly taken from coccygeal vein for determination of T3 and T4. The average daily gain in the cooled group gain (1.46kg/d) was similar (P=0.21) to non-cooled group (1.37kg/d). Body surface temperature (35.9ºC vs 38.7ºC) and respiratory frequency per minute (77 vs 104) were lower (P<0.01) in the cooled group than in non-cooled group, respectively. Triiodotironine levels were similar (P=0.30) in cooled (0.80ng/mL) and non-cooled (0.87ng/mL) groups, while, tiroxine level was lower (P<0.01) in cooled group (44.0ng/mL) compared to non-cooled group (56.6ng/mL). The cooling system did not improve productive parameters but the welfare in the cooled group was increased.<br>Avaliou-se um sistema de resfriamento para aumentar a eficiência produtiva e o bem-estar de novilhos durante o verão. Utilizaram-se 60 animais em fase de acabamento, distribuídos aleatoriamente em dois grupos: os do grupo-controle permaneceram somente sob sombra (grupo não resfriado) e os do grupo sob sistema de resfriamento, sob área sombreada, diariamente, das 9 às 18h, durante 69 dias de estudo. As médias registradas de temperatura ambiente e umidade relativa foram 35,4°C e 35,3°C, respectivamente, com índice de temperatura-umidade de 81,4 durante o período de estudo. O peso individual foi anotado a cada duas semanas, e a temperatura da superfície corporal e a frequência respiratória foram registrados três vezes por semana. Amostras de sangue foram tomadas da veia coccígea duas vezes por semana para determinação de T3 e T4. O ganho médio diário no grupo sob resfriamento (1,46kg/dia) foi similar (P=0,21) ao do grupo-controle (1,37kg/dia). A temperatura da superfície corporal (35,9°C versus 38,7°C) e a frequência respiratória/minuto (77 versus 104) foram mais baixas (P<0,01) no grupo sob resfriamento do que no grupo-controle (P<0,01), respectivamente. Níveis de triiodotironina foram similares (P=0,30) em animais com resfriamento (0,80ng/mL) e sem resfriamento (0,87ng/mL), enquanto o nível de tiroxina foi mais baixo (P<0,01) no grupo com resfriamento (44,0ng/mL versus 56,6ng/mL). O sistema de resfriamento não afetou parâmetros produtivos, porém o bem-estar dos animais do grupo com resfriamento foi melhor