The Hardness-Intensity Diagram of Cygnus X-3: Revisiting the Radio/X-Ray States

Cygnus X-3 is one of the brightest X-ray and radio sources in the Galaxy, and is well known for its erratic behaviour in X-rays as well as in the radio, occasionally producing major radio flares associated with relativistic ejections. However, even after many years of observations in various wavelength bands Cyg X-3 still eludes clear physical understanding. Studying different emission bands simultaneously in microquasars has proved to be a fruitful approach towards understanding these systems, especially by shedding light on the accretion disc/jet connection. We continue this legacy by constructing a hardness-intensity diagram (HID) from archival Rossi X-ray Timing Explorer data and linking simultaneous radio observations to it. We find that surprisingly Cyg X-3 sketches a similar shape in the HID to that seen in other transient black hole X-ray binaries during outburst but with distinct differences. Together with the results of this analysis and previous studies of Cyg X-3 we conclude that the X-ray states can be assigned to six distinct states. This categorization relies heavily on the simultaneous radio observations and we identify one new X-ray state, the hypersoft state, similar to the ultrasoft state, which is associated to the quenched radio state during which there is no or very faint radio emission. Recent observations of GeV flux observed from Cyg X-3 (Tavani et al. 2009; Fermi LAT Collaboration et al. 2009) during a soft X-ray and/or radio quenched state at the onset of a major radio flare hint that a very energetic process is at work during this time, which is also when the hypersoft X-ray state is observed. In addition, Cyg X-3 shows flaring with a wide range of hardness.Comment: 17 pages, 9 figures, accepted for publication in MNRA

CYGNUS X-3: ITS LITTLE FRIEND’S COUNTERPART, THE DISTANCE TO CYGNUS X-3, AND OUTFLOWS/JETS

Chandra observations have revealed a feature within 16'' of Cygnus X-3 that varied in phase with Cygnus X-3. This feature was shown to be a Bok globule that is along the line of sight to Cygnus X-3. We report on observations made with the Submillimeter Array to search for molecular emission from this globule, also known as Cygnus X-3's "Little Friend." We have found a counterpart in both [superscript 12]CO (2-1) and [superscript 13]CO (2-1) emission. From the velocity shift of the molecular lines we are able to find two probable distances based on the Bayesian model of Milky Way kinematics of Reid et al. For the LF velocity of −47.5 km s[superscript −1], we find distances of 6.1 ± 0.6 kpc (62% probability) and 7.8 ± 0.6 kpc (38% probability). This yields distances to Cyg X-3 of 7.4 ± 1.1 kpc and 10.2 ± 1.2 kpc, respectively. Based on the probabilities entailed, we take 7.4 ± 1.1 kpc as the preferred distance to Cyg X-3. We also report the discovery of bipolar molecular outflow, suggesting that there is active star formation occurring within the Little Friend

A Pedagogical Mystique?: Lessons of Incorporating Feminism Into Skills-Based Communication Courses

It is imperative that today’s advertising, journalism, mass communication, and public relations students are prepared to engage in corporate activism and corporate social responsibility communications once in the workforce. This article explores the need for incorporating equity-based pedagogy, using feminism as one of many approaches, into skills-based communication courses. The researchers conducted 20 qualitative interviews with academics to discuss various approaches, examples, and learnings. The findings suggest that using a feminist framework to teach skills: (1) enhances the skill being taught, (2) allows students to communicate more effectively, (3) builds life skills, and (4) comes in many forms. The article concludes with consideration to areas for future research and contributes to the understanding of academics engaged in a feminist approach to teaching skills-based communication courses

Orbital modulation of X-ray emission lines in Cygnus X-3

We address the problem where the X-ray emission lines are formed and investigate orbital dynamics using Chandra HETG observations, photoionizing calculations and numerical wind-particle simulations.The observed Si XIV (6.185 A) and S XVI (4.733 A) line profiles at four orbital phases were fitted with P Cygni-type profiles consisting of an emission and a blue-shifted absorption component. In the models, the emission originates in the photoionized wind of the WR companion illuminated by a hybrid source: the X-ray radiation of the compact star and the photospheric EUV-radiation from the WR star. The emission component exhibits maximum blue-shift at phase 0.5 (when the compact star is in front), while the velocity of the absorption component is constant (around -900 km/s). The simulated FeXXVI Ly alpha line (1.78 A) from the wind is weak compared to the observed one. We suggest that it originates in the vicinity of the compact star, with a maximum blue shift at phase 0.25 (compact star approaching). By combining the mass function derived with that from the infrared HeI absorption (arising from the WR companion), we constrain the masses and inclination of the system. Both a neutron star at large inclination (over 60 degrees) and a black hole at small inclination are possible solutions.Comment: 8 pages, accepted 19/04/2009 for publication in Astronomy and Astrophysic

Live Well Springfield (LWS): Measuring Baseline Usage of the Springfield River Walk

OBJECTIVE: To measure RW usage prior to implementation of a targeted LWS intervention. METHODS: Users were automatically counted by TRAFx infrared trail counters, which were installed at three locations along the RW – Brightwood, Boathouse, and Depot. Data are expressed in counts, not in number of people, because the counters cannot determine user identity. Data represent counts from August through October 2013. RESULTS: The median daily counts for the Brightwood, Boathouse, and Depot locations were 70, 96, 181, respectively; mean counts were 69, 97, 189, respectively; and the range in counts were 39-133, 18-209, and 52-374, respectively. Hourly distributions varied. DISCUSSION: Brightwood had relatively high counts during the 6 PM hour (6:00 to 6:59), suggesting nearby residents using the trail after work. Boathouse counts showed no sharp hourly peaks, suggesting usage is less related to a typical work schedule. Depot counts peaked sharply during the 12 PM and 1 PM hours, suggesting employees from downtown using the trail on their lunch break. The range in counts at each location suggests that weather affected usage overall, while differences between locations suggest that characteristics of each location played a large role in determining counts. CONCLUSION: Results of this study will inform LWS programming and lay the foundation for post-intervention comparisons

BATSE observations of BL Lac Objects

The Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory has been shown to be sensitive to non-transient hard X-ray sources in our galaxy, down to flux levels of 100 mCrab for daily measurements, 3 mCrab for integrations over several years. We use the continuous BATSE database and the Earth Occultation technique to extract average flux values between 20 and 200 keV from complete radio- and X-ray- selected BL Lac samples over a 2 year period