public/monitor/Get-ArgMonitorAlertsLast2Hours.ps1

function Get-ArgMonitorAlertsLast2Hours {
    $query = @"
alertsmanagementresources
| where type =~ 'microsoft.alertsmanagement/alerts' 
| where todatetime(properties.essentials.startDateTime) >= ago(2h) and todatetime(properties.essentials.startDateTime) < now()
| project Severity = tostring(properties.essentials.severity),
MonitorCondition = tostring(properties.essentials.monitorCondition),
ObjectState = tostring(properties.essentials.alertState),
MonitorService = tostring(properties.essentials.monitorService),
AlertRuleId = tostring(properties.essentials.alertRule),
SignalType = tostring(properties.essentials.signalType),
TargetResource = tostring(properties.essentials.targetResourceName),
TargetResourceType = tostring(properties.essentials.targetResourceName), id 
| summarize AlertsCount = count() by Severity, MonitorService , TargetResourceType
"@

    Search-AzGraph -Query $query
}