Evidence for 1809 keV Gamma-Ray Emission from 26Al Decays in the Vela Region with INTEGRAL/SPI

TL;DR

This study reports the detection of 1.8 MeV gamma-ray emission from 26Al decays in the Vela region using INTEGRAL/SPI, confirming previous claims and providing new flux measurements.

Contribution

First detection of 1.8 MeV gamma-rays from 26Al in Vela with INTEGRAL/SPI, improving flux estimates and confirming prior observations.

Findings

Detected 1.8 MeV gamma-ray flux of (6.5 ± 1.9(stat) ± 2.4(syst)) x 10^-5 ph/cm^2/s.

Confirmed previous COMPTEL detection at a similar flux level.

Provided new constraints on 26Al production in the Vela region.

Abstract

The Vela region is a promising target for the detection of 1.8 MeV gamma-rays emitted by the decays of radioactive 26Al isotopes produced in hydrostatic or explosive stellar nucleosynthesis processes. COMPTEL has claimed 1.8 MeV gamma-ray detection from Vela at a 3sigma level with a flux of 3.6 10^-5 ph/cm^2/s. In this paper, we present first results of our search for 1.8 MeV gamma-rays from Vela with the spectrometer SPI aboard INTEGRAL. Using the data set acquired during 1.7 Ms at the end of 2005 in the frame of our AO-3 open-time observation, we determine a flux of (6.5 \pm 1.9(stat) \pm 2.4(syst)) 10^-5 ph/cm^2/s from 26Al decays in the Vela region.