The Orbital Period of the Ultraluminous X-ray Source in M82

The ultraluminous x-ray source (ULX) in the galaxy M82 has been identified as a possible intermediate-mass black hole. We have found that the x-ray flux from M82 is modulated with a peak-to-peak amplitude corresponding to an isotropic luminosity of 2.4x10^40 erg/s in M82 and a period of 62.0 +/- 2.5 days, which we interpret as the orbital period of the ULX binary. This orbital period implies that the mass-donor star must be a giant or supergiant. Large mass-transfer rates, sufficient to fuel the ULX, are expected for a giant-phase mass donor in an x-ray binary. The giant phase has a short lifetime, indicating that we see the ULX in M82 in a brief and unusual period of its evolution.Comment: 3 pages, appeared in Scienc

VLA Detection of the Ionized Stellar Winds Arising from Massive Stars in the Galactic Center Arches Cluster

The Galactic center Arches stellar cluster, detected and studied until now only in the near-infrared, is comprised of at least one hundred massive (M>20 Msun) stars. Here we report the detection at centimeter wavelengths of radio continuum emission from eight radio sources associated with the cluster. Seven of these radio sources have rising spectral indices between 4.9 and 8.5 GHz and coincide spatially with the brightest stars in the cluster, as determine from JHK photometry and Brackett alpha and Brackett Gamma spectroscopy. Our results confirm the presence of powerful ionized winds in these stars. The eighth radio source has a nonthermal spectrum and its nature is yet unclear, but it could be associated with a lower mass young star in the cluster.Comment: 6 pages, 2 embedded figures, accepted to ApJLetter

Industrieforschung in Ostdeutschland: Welchen Beitrag leisten die externen Industrieforschungseinrichtungen?

Das ostdeutsche Forschungs- und Innovationssystem ist einerseits durch eine gut ausgebaute öffentliche Wissenschaftsinfrastruktur und andererseits durch ein relativ niedriges Niveau an industrieller Forschung und Entwicklung (FuE) charakterisiert. So erreichen die FuE-Ausgaben in der ostdeutschen Wissenschaft – gemessen am Bruttoregionalprodukt – das Niveau der Alten Bundesländer, während die FuE-Ausgaben der ostdeutschen Industrie deutlich unter Westniveau liegen. Ursächlich dafür ist die nach wie vor kleinteilig geprägte ostdeutsche Wirtschaft, es fehlen Großunternehmen und Konzernzentralen. Industrielle FuE geht daher in Ostdeutschland im Wesentlichen von kleinen und mittleren Unternehmen (KMU) aus. Diese können jedoch die Lücke, die durch die fehlende FuE der Großunternehmen entsteht, nicht komplett schließen. An dieser Stelle setzen die externen Industrieforschungseinrichtungen (IFE) an. Sie sind gemeinnützig und verstehen sich als FuE-Dienstleister. Die Ergebnisse ihrer FuE-Tätigkeit stellen sie der Allgemeinheit zur Verfügung, führen jedoch auch Aufträge der Privatwirtschaft aus. Im Vergleich zu kleinen und mittleren Unternehmen verfügen die IFE über deutlich größere FuE-Einheiten und können ein wesentlich breiteres Kompetenzfeld anbieten. Der Fokus liegt dabei auf Hochtechnologien. Im ostdeutschen Innovationssystem sind sie ein wichtiger Akteur und unterstützen ostdeutsche KMU in deren Innovationsbemühungen

A VLA Study of Newly-Discovered Southern Latitude Non-Thermal Filaments in the Galactic Center: Radio Continuum Total-intensity and Spectral Index Properties

The non-thermal filament (NTF) radio structures clustered within a few hundred parsecs of the Galactic Center (GC) are apparently unique to this region of the Galaxy. Recent radio images of the GC using MeerKAT at 1 GHz have revealed a multitude of faint, previously unknown NTF bundles (NTFBs), some of which are comprised of as many as 10 or more individual filaments. In this work we present Very Large Array (VLA) observations at C- and X-bands (4 - 12 GHz) at arcsecond-scale resolutions of three of these newly-discovered NTFBs, all located at southern Galactic latitudes. These observations allow us to compare their total-intensity properties with those of the larger NTF population. We find that these targets generally possess properties similar to what is observed in the larger NTF population. However, the larger NTF population generally has steeper spectral index values than what we observe for our chosen targets. The results presented here based on the total-intensity properties of these structures indicate that the NTFs are likely all formed from Cosmic Rays (CRs). These CRs are either generated by a nearby compact source and then diffuse along the NTF lengths or are generated by extended, magnetized structures whose magnetic field undergoes reconnection with the NTF magnetic field.Comment: 18 pages, 13 figures, 2 tables. Submitted to ApJ for peer-revie

Multiwavelength Observations of Massive Stellar Cluster Candidates in the Galaxy

The Galaxy appears to be richer in young, massive stellar clusters than previously known, due to advances in infrared surveys which have uncovered deeply embedded regions of star formation. Young, massive clusters can significantly impact the surrounding interstellar medium (ISM) and hence radio observations can also be an important tracer of their activity. Several hundred cluster candidates are now known by examining survey data. Here we report on multiwavelength observations of six of these candidates in the Galaxy. We carried out 4.9 and 8.5 GHz VLA observations of the radio emission associated with these clusters to obtain the physical characteristics of the surrounding gas, including the Lyman continuum photon flux and ionized gas mass. Spitzer Infrared Array Camera observations were also made of these regions, and provide details on the stellar population as well as the dust continuum and polycyclic aromatic hydrocarbon emission. When compared to the known young, massive clusters in the Galaxy, the six cluster candidates have less powerful Lyman ionizing fluxes and ionize less of the H II mass in the surrounding ISM. Therefore, these cluster candidates appear to be more consistent with intermediate-mass clusters (10^3-10^4 Msun).Comment: 39 pages, 20 figures. Accepted in the Astronomical Journal; to be published Fall 201

A Radio Transient 0.1 pc from Sagittarius A*

We report the discovery of a transient radio source 2.7 arcsec (0.1 pc projected distance) South of the Galactic Center massive black hole, Sagittarius A*. The source flared with a peak of at least 80 mJy in March 2004. The source was resolved by the Very Large Array into two components with a separation of ~0.7 arcsec and characteristic sizes of ~0.2 arcsec. The two components of the source faded with a power-law index of 1.1 +/- 0.1. We detect an upper limit to the proper motion of the Eastern component of ~3 x 10^3 km s^-1 relative to Sgr A*. We detect a proper motion of ~10^4 km s^-1 for the Western component relative to Sgr A*. The transient was also detected at X-ray wavelengths with the Chandra X-ray Observatory and the XMM-Newton telescope and given the designation CXOGC J174540.0-290031. The X-ray source falls in between the two radio components. The maximum luminosity of the X-ray source is ~10^36 erg s^-1, significantly sub-Eddington. The radio jet flux density predicted by the X-ray/radio correlation for X-ray binaries is orders of magnitude less than the measured flux density. We conclude that the radio transient is the result of a bipolar jet originating in a single impulsive event from the X-ray source and interacting with the dense interstellar medium of the Galactic Center.Comment: accepted in ApJ; 24 pages; 8 figure