如何删除图形和子图中标题的中心？

Question

我在移除图中标题的居中时遇到了麻烦，我justification==justified也试过了，但没用。另外，我试过\raggedright在标题中，它将标题移到了左边距，但没有对齐（连字符没有出现）。我也试过了\usepackage{ragged2e}，\RaggedRight但什么都没用。我preprint在文档类中使用。

\documentclass[preprint,pre,amsmath]{revtex4-2}
\usepackage[pdftex]{graphicx} 
\usepackage{color}
\usepackage{bm}
\usepackage{epsfig}
\usepackage{latexsym}
\usepackage{subcaption}
\usepackage{caption}
\usepackage[font=small,labelfont=bf,justification=justified]{caption}
\begin{document}
\begin{figure}[t]
 \centering
\begin{subfigure}{0.49\textwidth}
     \centering
     \includegraphics[width=1.0\textwidth]{plot1.png}
     %\caption{}
     \label{figa}
 \end{subfigure}
 %\hfill
 \begin{subfigure}{0.49\textwidth}
     \centering
     \includegraphics[width=1.0\textwidth]{plot2.png}
    %\caption{}
    \label{figb}
 \end{subfigure}
% \hfill
 \caption{\raggedright Solar atmosphere temperature-height distribution.Solar atmosphere temperature-height distribution as determined by \cite{15}. Height is given in kilometers measured above zero point where $\tau=1$. Regions of line formation are also indicated. From right to left: photosphere, temperature minimum (4,000K), chromosphere, transition region (8,500K) and Lyman valley (20,000K).}
\label{fig}
\end{figure}
\end{document}