Non-thermal radio emission from colliding flows in classical nova V1723 Aql

The importance of shocks in nova explosions has been highlighted by Fermi's discovery of \u3b3-ray-producing novae. Over three years of multiband Very Large Array radio observations of the 2010 nova V1723 Aql show that shocks between fast and slow flows within the ejecta led to the acceleration of particles and the production of synchrotron radiation. Soon after the start of the eruption, shocks in the ejecta produced an unexpected radio flare, resulting in a multipeaked radio light curve. The emission eventually became consistent with an expanding thermal remnant with mass 2 7 10\u207b\u2074\u2009M 99 and temperature 10\u2074 K. However, during the first two months, the 7310\u2076 K brightness temperature at low frequencies was too high to be due to thermal emission from the small amount of X-ray-producing shock-heated gas. Radio imaging showed structures with velocities of 400 km s\u207b\ub9\u2009(d/6\u2009kpc) in the plane of the sky, perpendicular to a more elongated 1500 km s\u207b\ub9\u2009(d/6\u2009kpc) flow. The morpho-kinematic structure of the ejecta from V1723 Aql appears similar to nova V959 Mon, where collisions between a slow torus and a faster flow collimated the fast flow and gave rise to \u3b3-ray-producing shocks. Optical spectroscopy and X-ray observations of V1723 Aql during the radio flare are consistent with this picture. Our observations support the idea that shocks in novae occur when a fast flow collides with a slow collimating torus. Such shocks could be responsible for hard X-ray emission, \u3b3-ray production, and double-peaked radio light curves from some classical novae.Peer reviewed: YesNRC publication: Ye

Classical novae at radio wavelengths

We present radio observations (1-40 GHz) for 36 classical novae, representing data from over five decades compiled from the literature, telescope archives, and our own programs. Our targets display a striking diversity in their optical parameters (e.g., spanning optical fading timescales, t 2 = 1-263 days), and we find a similar diversity in the radio light curves. Using a brightness temperature analysis, we find that radio emission from novae is a mixture of thermal and synchrotron emission, with nonthermal emission observed at earlier times. We identify high brightness temperature emission (T B > 5 104 K) as an indication of synchrotron emission in at least nine (25%) of the novae. We find a class of synchrotron-dominated novae with mildly evolved companions, exemplified by V5589 Sgr and V392 Per, that appear to be a bridge between classical novae with dwarf companions and symbiotic binaries with giant companions. Four of the novae in our sample have two distinct radio maxima (the first dominated by synchrotron and the later by thermal emission), and in four cases the early synchrotron peak is temporally coincident with a dramatic dip in the optical light curve, hinting at a common site for particle acceleration and dust formation. We publish the light curves in a machine-readable table and encourage the use of these data by the broader community in multiwavelength studies and modeling efforts

Junction 2016 Presentation & Poster Repository

I hope this will serve as an archive for all the talks and posters so others who are interested can go back and have a closer look. Please upload a PDF version of your Junction talk/poster using the following steps: 1) Sign up for an OSF account 2) Click the plus symbol next to "OSF Storage" under the "Files" section to view the folders where the talks/posters will be uploaded. 3) Select your name/talk title. Make sure it is highlighted in dark blue. (listed alphabetically by first name) 4) Click "Upload" at the top of the Files section and attach a PDF version of your talk/poster. Enjoy