Scaling laws of quasi-periodic pulsations in solar flares. (arXiv:1902.09627v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pugh_C/0/1/0/all/0/1">C. E. Pugh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Broomhall_A/0/1/0/all/0/1">A.-M. Broomhall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nakariakov_V/0/1/0/all/0/1">V. M. Nakariakov</a>
Quasi-periodic pulsations (QPPs) are a common feature of solar flares, but
previously there has been a lack of observational evidence to support any of
the theoretical models that might explain the origin of QPPs. We aimed to
determine if there are any relationships between the QPP period and other
properties of the flaring region, using the sample of flares with QPPs from
Pugh et al. (2017b). If any relationships exist then these can be compared with
scaling laws for the theoretical QPP mechanisms. To obtain the flaring region
properties we made use of the AIA 1600 and HMI data. The AIA 1600 images allow
the flare ribbons to be seen while the HMI magnetograms allow the positive and
negative magnetic polarity ribbons to be distinguished and the magnetic
properties determined. The ribbon properties calculated in this study were the
ribbon separation distance, area, total unsigned magnetic flux, and average
magnetic field strength. Only the flares that occurred within pm 60{deg} of
the solar disk centre were included, which meant a sample of 20 flares with 22
QPP signals. Positive correlations were found between the QPP period and the
ribbon properties. The strongest correlations were with the separation distance
and magnetic flux. Because these ribbon properties also correlate with the
flare duration, and the relationship between the QPP period and flare duration
may be influenced by observational bias, we also made use of simulated data to
check if artificial correlations could be introduced. These simulations show
that although QPPs cannot be detected for certain combinations of QPP period
and flare duration, this does not introduce an apparent correlation. There is
evidence of relationships between the QPP period and flare ribbon properties,
and in the future the derived scaling laws between these properties can be
compared to equivalent scaling laws for theoretical QPP mechanisms.
Quasi-periodic pulsations (QPPs) are a common feature of solar flares, but
previously there has been a lack of observational evidence to support any of
the theoretical models that might explain the origin of QPPs. We aimed to
determine if there are any relationships between the QPP period and other
properties of the flaring region, using the sample of flares with QPPs from
Pugh et al. (2017b). If any relationships exist then these can be compared with
scaling laws for the theoretical QPP mechanisms. To obtain the flaring region
properties we made use of the AIA 1600 and HMI data. The AIA 1600 images allow
the flare ribbons to be seen while the HMI magnetograms allow the positive and
negative magnetic polarity ribbons to be distinguished and the magnetic
properties determined. The ribbon properties calculated in this study were the
ribbon separation distance, area, total unsigned magnetic flux, and average
magnetic field strength. Only the flares that occurred within pm 60{deg} of
the solar disk centre were included, which meant a sample of 20 flares with 22
QPP signals. Positive correlations were found between the QPP period and the
ribbon properties. The strongest correlations were with the separation distance
and magnetic flux. Because these ribbon properties also correlate with the
flare duration, and the relationship between the QPP period and flare duration
may be influenced by observational bias, we also made use of simulated data to
check if artificial correlations could be introduced. These simulations show
that although QPPs cannot be detected for certain combinations of QPP period
and flare duration, this does not introduce an apparent correlation. There is
evidence of relationships between the QPP period and flare ribbon properties,
and in the future the derived scaling laws between these properties can be
compared to equivalent scaling laws for theoretical QPP mechanisms.
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