Exploring the Optical Transient Sky with the Palomar Transient Factory (0906.5355v1)

Abstract: The Palomar Transient Factory (PTF) is a wide-field experiment designed to investigate the optical transient and variable sky on time scales from minutes to years. PTF uses the CFH12k mosaic camera, with a field of view of 7.9 deg^2 and a plate scale of 1 asec/pixel, mounted on the the Palomar Observatory 48-inch Samuel Oschin Telescope. The PTF operation strategy is devised to probe the existing gaps in the transient phase space and to search for theoretically predicted, but not yet detected, phenomena, such as fallback supernovae, macronovae, .Ia supernovae and the orphan afterglows of gamma-ray bursts. PTF will also discover many new members of known source classes, from cataclysmic variables in their various avatars to supernovae and active galactic nuclei, and will provide important insights into understanding galactic dynamics (through RR Lyrae stars) and the Solar system (asteroids and near-Earth objects). The lessons that can be learned from PTF will be essential for the preparation of future large synoptic sky surveys like the Large Synoptic Survey Telescope. In this paper we present the scientific motivation for PTF and describe in detail the goals and expectations for this experiment.

• The paper demonstrates that the PTF’s untargeted, wide-field survey using the CFH12k mosaic camera effectively reveals faint and rare optical transient events.
• It details a robust methodology including the five-day cadence and dynamic cadence experiments, highlighting key strategies for capturing variable astrophysical phenomena.
• The findings inform future surveys like LSST by refining models of stellar evolution and observational techniques for transient detection.

Analysis of "Exploring the Optical Transient Sky with the Palomar Transient Factory"

The paper "Exploring the Optical Transient Sky with the Palomar Transient Factory" outlines the objectives and strategies of the Palomar Transient Factory (PTF), a project designed to perform a systematic exploration of the optical transient and variable sky. The PTF employs the CFH12k mosaic camera at the Palomar Observatory, aimed at filling existing gaps in the transient phase space and potentially discovering new classes of astronomical phenomena. The project's pivotal role is highlighted through its broad observational reach, operating strategy, and expected contributions to future large synoptic sky surveys.

Instrumentation and Survey Strategy

The Palomar Transient Factory leverages the CFH12k mosaic camera, previously utilized at the Canada-France-Hawaii Telescope, and now installed on the 48-inch Samuel Oschin Telescope. This setup enables a substantial field of view of 7.9 square degrees, which is crucial in achieving the PTF's goal of wide-field transient detection. Observations are primarily conducted in the Mould-$R$ and sdss-$g$ filters, with the flexibility to incorporate narrow-band filters as necessary. Typical observations achieve a limiting magnitude of $R\approx21.0$, $g'\approx21.6$, thus enabling the detection of faint transient phenomena that might otherwise go unnoticed.

Several predefined experiments under PTF aim to address particular scientific questions with specific cadence and filter strategies, such as the five-day cadence survey (5DC) and dynamic cadence experiment (DyC), alongside continuous monitoring of regions like those in Orion. This multi-pronged strategy enhances the project's capacity to monitor a variety of variables and transient events ranging from minor galactic incidents to extensive cosmological phenomena.

Scientific Goals and Expected Outcomes

The breadth of scientific inquiries enabled by PTF is notable, spanning from rapidly evolving transients to persistent but variable astrophysical objects. For instance, the PTF is set to explore the dynamics and characteristics of cataclysmic variables, including the likes of classical novae and dwarf novae, providing insight into phenomena such as accretion disk mechanisms and stellar evolution pathways.

The paper of supernovae, particularly the Type Ia and core-collapse variety, represents a significant focus, with an expectation of leveraging these observations to enhance the precision of cosmological models and the understanding of massive stellar life cycles. Similarly, identifying less common forms of stellar explosion, such as .Ia supernovae and luminous red novae, adds to the scope of discovery, potentially unveiling new theoretical underpinnings for observed cosmic activities.

PTF's untargeted, wide-field survey approach is indispensable for capturing rare events and phenomena. The detection of events such as orphan gamma-ray bursts and tidal disruption flares is anticipated, offering data to refine existing models for transient high-energy phenomena and black hole astrophysics.

Importantly, the paper details how PTF's findings will have profound implications for future astronomical studies. It is poised to provide data that will refine the methodologies and techniques deployed in forthcoming surveys like the Large Synoptic Survey Telescope (LSST).

Implications and Future Directions

PTF stands as a critical precursor to subsequent synoptic surveys, offering both a practical framework and a scientific benchmark. Its contributions to our understanding of variable and transient celestial phenomena will inform the next generation of celestial surveys and improve strategies for examining an evolving Universe.

Beyond this, PTF's discoveries could inspire refined models for stellar and galactic behavior, particularly in the context of multi-messenger astronomy, where the combination of electromagnetic and non-electromagnetic information fosters a broader comprehension of cosmic phenomena.

In conclusion, the Palomar Transient Factory project highlights a systematic and comprehensive approach to the paper of optical transients and variables. Through its extensive coverage, innovative observation strategies, and analytical depth, PTF exemplifies the potential for significant breakthroughs in astronomy and sets the stage for future explorations of the dynamic night sky.