\documentclass[9pt]{book}

\usepackage{verbatim}
\usepackage[normalem]{ulem}
\usepackage[a4paper,margin=3cm,innermargin=2.5cm]{geometry}
\usepackage{fix-cm}
\usepackage{bbm}
\usepackage{fancyhdr} 
\pagestyle{fancy} 
\fancyhead{} 
\fancyfoot{} 
\lhead{Inverse Days 2018, December 11-13, 2018, Helsinki, Finland}
\rhead{\thepage}

\renewcommand{\headrulewidth}{0.3pt}
\fancypagestyle{plain}{
	
\renewcommand{\headrulewidth}{0.3pt}
\renewcommand{\footrulewidth}{0pt}}
%%%%%
\usepackage{graphicx,psfrag}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{needspace}
\usepackage{marginnote}
\renewcommand*{\marginfont}{\sffamily\footnotesize}

\usepackage[dvipsnames]{xcolor}
\usepackage{imakeidx}
\usepackage[colorlinks=false, linktocpage=true]{hyperref}
\makeindex[intoc]

\newcommand{\indi}{\mathbbm{1}}

\newenvironment{conf-abstract}[4][]{
	\needspace{10\baselineskip}
	\begin{center}
		{ \renewcommand\textsuperscript[1]{}
			%      \phantomsection\addcontentsline{toc}{section}
			%      {\texorpdfstring{#2 (\emph{#3})}{#2 (#3)}}
		}
		{{\large\bfseries #2}\marginnote{#1}\par}
		%    {{\large\bfseries #2}\par}
		\medskip
		{#3\par}
		\smallskip
		{\small #4\par}
	\end{center}
}{%
	\bigskip
	\hrule
	\bigskip
}


\usepackage{etoolbox}
\newcommand{\indexauthors}[1]{%
	\forcsvlist{\index}{#1}
}

\setcounter{tocdepth}{3}
\setcounter{secnumdepth}{-1}

\begin{document}
	
	\chapter{Abstracts}

\begin{conf-abstract}[leave empty\\hh:mm-hh:mm\\Lecture hall ...]
{\Large{Here goes the title}}
{the author}
{the affiliation}
\indexauthors{{surname, name}}
\label{author}

Here goes the text, with any mathematical symbols $ \mathcal{A} $, $ \mathbb{R} $, $ \partial \Omega $, $ \% $\\
no need to put here any additional macros \\
save this file as 'surname\_name.tex'

\end{conf-abstract}

\end{document}