Video Experimental Relacionado
Updated: Sep 20, 2025
08:54
Monitoring Leucine-Rich Repeat Containing 8 Channel (LRRC8/VRAC) Activity Using Sensitized-Emission Förster Resonance Energy Transfer (SE-FRET)
Published on: August 9, 2024
534
Una ráfaga de radio rápida y repetida asociada con una fuente de radio persistente
C-H Niu1, K Aggarwal2,3, D Li4,5,6
1National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China.
Nature
|June 8, 2022
Resumen
Las ráfagas rápidas de radio (FRB) pueden ayudar a estudiar el universo. Sin embargo, un FRB repetitivo, 20190520B, muestra una medida de alta dispersión de su galaxia anfitriona, desafiando suposiciones anteriores.
Área de la Ciencia:
- La astrofísica
- Cosmología
- La radioastronomía
Sus antecedentes:
- Las ráfagas rápidas de radio (FRB) se utilizan para sondear el contenido bariónico ionizado del medio intergaláctico.
- Las contribuciones de la galaxia anfitriona a la medida de dispersión (DM) generalmente se consideran menores.
- Estudios anteriores señalaron ambientes extremos y fuentes de radio persistentes para algunos FRB.
Objetivo del estudio:
- Para reportar la detección y localización de un FRB repetitivo, 20190520B.
- Para investigar las propiedades de la galaxia anfitriona y medir la contribución de dispersión de FRB 20190520B.
- Para evaluar el impacto de la galaxia anfitriona DM en las estimaciones de desplazamiento al rojo FRB.
Principales métodos:
- Detección y localización precisa del FRB 20190520B que se repite.
- Identificación de una fuente de radio compacta y persistente ubicada en el mismo lugar.
- Asociación con una galaxia anfitriona enana y medición de su corrimiento al rojo (0.241 ± 0.001).
Principales resultados:
- FRB 20190520B está co-ubicado con una fuente de radio persistente.
- La galaxia anfitriona exhibe una alta tasa específica de formación estelar.
- Se midió una medida de dispersión de galaxia anfitriona excepcionalmente alta (DM ≈ 1.2 × 10^4 pc cm-3), que excede significativamente la contribución del medio intergaláctico.
Conclusiones:
- La galaxia anfitriona DM para FRB 20190520B es casi un orden de magnitud mayor que el promedio para las galaxias anfitrionas de FRB conocidas.
- Este hallazgo desafía la suposición de que el medio intergaláctico domina la medida de dispersión total para todos los FRB.
- La identificación precisa de la galaxia anfitriona es crucial para las determinaciones confiables del desplazamiento al rojo de FRB.
Videos de Conceptos Relacionados
01:17NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
936
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
936
01:11Atomic Nuclei: Larmor Precession Frequency
1.8K
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession,...
1.8K
01:02Long-patch Base Excision Repair
7.2K
Since the discovery of the two BER pathways, there has been a debate about how a cell chooses one pathway over the other and the factors determining this selection. Numerous in vitro experiments have pointed out multiple determinants for the sub-pathway selection. These are:
7.2K
01:24IR Frequency Region: X–H Stretching
1.1K
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in...
1.1K
03:18Non-LTR Retrotransposons
11.9K
As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
11.9K
01:05Atomic Nuclei: Magnetic Resonance
767
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
767