Browsing by Author "Rupen, Michael P."
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Item Classical Novae at Radio Wavelengths(2021-07-13) Chomiuk, Laura; Linford, Justin D.; Aydi, Elias; Bannister, Keith W.; Mioduszewski, Amy J.; Mukai, Koji; Nelson, Thomas J.; Rupen, Michael P.; Ryder, Stuart D.; Sokoloski, Jennifer L.; Sokolovsky, Kirill V.; Strader, Jay; Filipovic, Miroslav D.; Finzell, Tom; Kawash, Adam; Kool, Erik C.; Metzger, Brian D.; Nyamai, Miriam M.; Ribeiro, Valerio A.R.M.; Roy, Nirupam; Urquhart, Ryan; Weston, JenniferWe 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, t₂ = 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 non-thermal emission observed at earlier times. We identify high brightness temperature emission (T_B > 5x10⁴ K) as an indication of synchrotron emission in at least 9 (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 as tables and encourage use of these data by the broader community in multi-wavelength studies and modeling efforts.Item A Shocking Shift in Paradigm for Classical Novae(2019-03-19) Chomiuk, Laura; Aydi, Elias; Babul, Aliya-Nur; Derdzinski, Andrea; Kawash, Adam; Li, Kwan-Lok; Linford, Justin; Metzger, Brian D.; Mukai, Koji; Rupen, Michael P.; Sokoloski, Jennifer; Sokolovsky, Kirill; Steinberg, EladThe discovery of GeV gamma-rays from classical novae has led to a reassessment of these garden-variety explosions, and highlighted their importance for understanding radiative shocks, particle acceleration, and dust formation in more exotic, distant transients. Recent collaboration between observers and theorists has revealed that shocks in novae are energetically important, and can even dominate their bolometric luminosity. Shocks may also explain long-standing mysteries in novae such as dust production, super-Eddington luminosities, and `flares' in optical light curves. Here, we highlight the multi-wavelength facilities of the next decade that will further test our nova shock model and fulfill the promise of novae as powerful astrophysical laboratories.Item A Shocking Shift in Paradigm for Classical Novae(2019-03-19) Chomiuk, Laura; Aydi, Elias; Babul, Aliya-Nur; Derdzinski, Andrea; Kawash, Adam; Li, Kwan-Lok; Linford, Justin; Metzger, Brian D.; Mukai, Koji; Rupen, Michael P.; Sokoloski, Jennifer; Sokolovsky, Kirill; Steinberg, EladThe discovery of GeV gamma-rays from classical novae has led to a reassessment of these garden-variety explosions, and highlighted their importance for understanding radiative shocks, particle acceleration, and dust formation in more exotic, distant transients. Recent collaboration between observers and theorists has revealed that shocks in novae are energetically important, and can even dominate their bolometric luminosity. Shocks may also explain long-standing mysteries in novae such as dust production, super-Eddington luminosities, and `flares' in optical light curves. Here, we highlight the multi-wavelength facilities of the next decade that will further test our nova shock model and fulfill the promise of novae as powerful astrophysical laboratories.Item X-ray evolution of the nova V959 Mon suggests a delayed ejection and a non-radiative shock(2020-07-30) Nelson, Thomas; Mukai, Koji; Chomiuk, Laura; Sokoloski, Jennifer L.; Linford, Justin D.; Finzell, Thomas; Mioduszewski, Amy J.; Rupen, Michael P.; Weston, Jennifer; Oliveira, Raimundo Lopes deX-ray observations of shocked gas in novae can provide a useful probe of the dynamics of the ejecta. Here we report on X-ray observations of the nova V959 Mon, which was also detected in GeV gamma-rays with the Fermi satellite. We find that the X-ray spectra are consistent with a two-temperature plasma model with non-solar abundances. We interpret the X-rays as due to shock interaction between the slow equatorial torus and the fast polar outflow that were inferred from radio observations of V959 Mon. We further propose that the hotter component, responsible for most of the flux, is from the reverse shock driven into the fast outflow. We find a systematic drop in the column density of the absorber between Days 60 and 140, consistent with the expectations for such a picture. We present intriguing evidence for a delay of around 40 days in the expulsion of the ejecta from the central binary. Moreover, we infer a relatively small (a few times 10⁻⁶ Msun) ejecta mass ahead of the shock, considerably lower than the mass of 10⁴ K gas inferred from radio observations. Finally, we infer that the dominant X-ray shock was likely not radiative at the time of our observations, and that the shock power was considerably higher than the observed X-ray luminosity. It is unclear why high X-ray luminosity, closer to the inferred shock power, is never seen in novae at early times, when the shock is expected to have high enough density to be radiative.