A search for possible interactions between ejections from GRS 1915+105 and the surrounding interstellar medium

¹ Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
² Service d'Astrophysique, DSM/DAPNIA/SAp, CEA/Saclay, L'Orme des Merisiers, Bât. 709, 91191 Gif-sur-Yvette Cedex, France
³ Instituto de Astronomía, UNAM, Campus Morelia, Morelia, Michoacán 58190, Mexico
⁴ Instituto de Astronomía y Física del Espacio C.C. 67, Suc. 28. 1428, Buenos Aires, Argentina
⁵ Gemini Observatory, 670 N. A'ohoku Place, Hilo, HI 96720, USA
⁶ ESO, Karl-Schwarzschild Strasse 2, 85748 Garching-bei-München, Germany
⁷ Université Paris XI, Institut d'Astrophysique Spatiale, Bât. 121, 91450 Orsay Cedex, France
⁸ Max Plank Institut für Extraterrestrische Physik, Postfach 1603, 85740 Garching, Germany

Corresponding author: S. Chaty, S.Chaty@open.ac.uk

Received: 25 July 2000
Accepted: 13 November 2000

Abstract

We have observed an extended region surrounding the first discovered galactic superluminal source GRS 1915+105, seeking evidence of interaction between the relativistic ejecta of that object and the interstellar medium. We find two radio sources axisymmetrically aligned along the sub-arcsecond relativistic ejecta of GRS 1915+105 and roughly 17′ distant from it, which coincide with the luminous IRAS sources 19124+1106 and 19132+1035. We have observed these sources at centimeter (VLA), millimeter (IRAM 30 m), and infrared (ISO, UKIRT, ESO/MPI 2.2 m) wavelengths in both line and continuum emission. At centimeter wavelengths a non-thermal jet-like feature aligned along the outflow axis is located adjacent to the inner edge of the southern source. Strong density enhancements are found in the millimeter tracers CO and at the positions of both sources and some of the morphology is reminiscent of shock-like interactions; however, linewidths are narrow. At infrared wavelengths strong hydrogen recombination lines and weak lines of molecular hydrogen are observed at the southern source. We discuss these results as possible evidence of the sought-after interaction, both in terms of the regions undergoing ongoing shock-heating and in terms of them being locations of shock-induced star formation. The evidence for each of these is inconclusive. Millimeter line mapping of a portion of W 50 where the relativistic jets of the X-ray binary interact with the interstellar medium shows roughly similar morphology as , suggesting that the phenomena observed at the IRAS sources may not be unusual for such a long distance interaction.