We are currently involved in a multifaceted campaign to study extragalactic classical novae in the Local Group and beyond. Here we report on-going results from the exploitation of the POINT-AGAPE M31 dataset; initial results from our Local Group imaging, and spectroscopic CNe follow-up campaign and introduce the Liverpool Extragalactic Nova Survey.
M31N 2017-09a is a classical nova and was observed for some 160 days following its initial eruption, during which time it underwent a number of bright secondary outbursts. The light-curve is characterized by continual variation with excursions of at least 0.5 magnitudes on a daily time-scale. The lower envelope of the eruption suggests that a single power-law can describe the decline rate. The eruption is relatively long with $t_2 = 111$, and $t_3 = 153$ days.
Since the IAU (maser-)Symposium 287 in Stellenbosch/South Africa (Jan. 2012), great progress has been achieved in studying extragalactic maser sources. Sensitivity has reached a level allowing for dedicated maser surveys of extragalactic objects. These included, during the last years, water vapor (H2O), methanol (CH3OH), and formaldehyde (H2CO), while surveys related to hydroxyl (OH), cyanoacetylene (HC3N) and ammonia (NH3) may soon become (again) relevant. Overall, with the upgraded Very Large Array (VLA), the Atacama Large Millimeter/submillimeter Array (ALMA), FAST (Five hundred meter Aperture Synthesis Telescope) and the low frequency arrays APERTIF (APERture Tile in Focus), ASKAP (Australian Square Kilometer Array Pathfinder) and MeerKAT (Meer Karoo Array Telescope), extragalactic maser studies are expected to flourish during the upcoming years. The following article provides a brief sketch of past achievements, ongoing projects and future perspectives.
A review of the present status of nova modeling is made, with a special emphasis on some specific aspects. What are the main nucleosynthetic products of the explosion and how do they depend on the white dwarf properties (e.g. mass, chemical composition: CO or ONe)? Whats the imprint of nova nucleosynthesis on meteoritic presolar grains? How can gamma rays, if observed with present or future instruments onboard satellites, constrain nova models through their nucleosynthesis? What have we learned about the turnoff of classical novae from observation with past and present X-ray observatories? And last but not least, what are the most critical issues concerning nova modeling (e.g. ejected masses, mixing mechanism between core and envelope)?
Deep surveys of the cosmic X-ray background are reviewed in the context of observational progress enabled by the Chandra X-ray Observatory and the X-ray Multi-Mirror Mission-Newton. The sources found by deep surveys are described along with their redshift and luminosity distributions, and the effectiveness of such surveys at selecting active galactic nuclei (AGN) is assessed. Some key results from deep surveys are highlighted including (1) measurements of AGN evolution and the growth of supermassive black holes, (2) constraints on the demography and physics of high-redshift AGN, (3) the X-ray AGN content of infrared and submillimeter galaxies, and (4) X-ray emission from distant starburst and normal galaxies. We also describe some outstanding problems and future prospects for deep extragalactic X-ray surveys.
We review the most important findings on AGN physics and cosmological evolution as obtained by extragalactic X-ray surveys and associated multiwavelength observations. We briefly discuss the perspectives for future enterprises and in particular the scientific case for an extremely deep (2-3 Ms) XMM survey.
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