LOFT – X-ray space observatory

The Large Observatory for X-ray Timing (LOFT) is a proposed space observatory that would be launched by the European Space Agency (ESA) to study the high-energy X-ray emission from a variety of cosmic sources. The mission is designed to investigate the behavior of matter in extreme conditions, such as those found in neutron stars, black holes, and the accretion disks that surround them.

When:

The LOFT mission was first proposed in 2011 as part of ESA's Cosmic Vision program, which aims to explore the fundamental questions of astrophysics and cosmology. In 2013, LOFT was selected as one of three missions that would receive funding for a two-year study phase to refine the scientific goals and technical specifications of the mission. The study phase ended in 2015, and since then, LOFT has been in the development phase. However, the project is currently on hold due to budget constraints.

Launching Date:

The launching date for LOFT is not yet confirmed, as the mission is still in the development phase. However, it was initially scheduled to launch in the mid-2020s, but with the current delay, it is not clear when the mission will be launched.

Why:

The primary goal of LOFT is to study the high-energy X-ray emission from compact objects in the universe. This includes neutron stars, black holes, and the accretion disks that surround them. These objects are some of the most extreme environments in the universe, and their study can provide insights into the fundamental laws of physics and the behavior of matter in extreme conditions.

LOFT is designed to address several key scientific questions, such as:

* What is the equation of state of matter in neutron stars?

* How do black holes accrete matter and produce jets?

* What is the structure of the innermost regions of accretion disks?

* What is the nature of the strong gravitational fields around compact objects?

* How are X-ray emission and variability generated in compact objects?

By studying these questions, LOFT aims to deepen our understanding of the universe and shed light on some of its most mysterious and fascinating phenomena.

How:

LOFT will be an X-ray telescope with a unique set of capabilities that make it well-suited for studying compact objects. The observatory will have a large collecting area and a wide field of view, allowing it to detect a large number of sources and monitor them over long periods of time. It will also have a high time resolution, allowing it to study rapid X-ray variability and pulsations from neutron stars and black holes.

The main instrument on LOFT will be a set of X-ray detectors called the Large Area Detector (LAD). The LAD will consist of a large number of silicon drift detectors (SDDs) that can measure the energy and arrival time of X-rays with high precision. The LAD will have a total collecting area of about 10 square meters, which is about ten times larger than that of previous X-ray telescopes such as Chandra and XMM-Newton.

In addition to the LAD, LOFT will also have a set of instruments called the Wide Field Monitor (WFM). The WFM will consist of two coded-mask cameras that can detect X-ray sources over a wide field of view. The WFM will provide a complementary view of the X-ray sky to that of the LAD, and will also be able to detect transient events such as X-ray bursts and flares.

LOFT will be placed in a low-Earth orbit, which will allow it to observe the entire sky over time. The mission is designed to last for at least five years, during which time it will observe thousands of X-ray sources and perform detailed studies of hundreds of compact objects.

Cost:

The cost of the LOFT mission is difficult to estimate accurately, as it is still in the development phase and its funding situation is unclear. However, the initial estimates for the mission's cost were in the range of 500 million to 1 billion euros. The project is currently on hold due to budget constraints, and it is not clear when it will resume.

Achievements:

If and when LOFT is launched, it has the potential to make significant contributions to our understanding of the universe. Some of the key scientific achievements that could be realized by LOFT include:

Measuring the equation of state of matter in neutron stars: By studying the X-ray emission from neutron stars, LOFT could provide information about their internal structure and the behavior of matter under extreme conditions. This could help to answer fundamental questions about the nature of matter and the laws of physics.

Studying the behavior of black holes: LOFT could provide detailed information about how black holes accrete matter and produce jets of material. This could help to answer questions about how black holes grow and evolve over time, and how they affect the galaxies in which they reside.

Mapping the inner regions of accretion disks: Accretion disks are the swirling disks of gas and dust that surround compact objects such as black holes and neutron stars. By studying the X-ray emission from these disks, LOFT could provide detailed information about their structure and dynamics.

Studying the strong gravitational fields around compact objects: LOFT could provide detailed information about the effects of strong gravitational fields on the behavior of matter. This could help to test Einstein's theory of general relativity and shed light on the nature of gravity itself.

Monitoring X-ray variability and transient events: By observing thousands of X-ray sources over time, LOFT could detect and study a wide range of transient events, such as X-ray bursts and flares. This could provide insights into the physical processes that drive these events and help to understand their role in the universe.

In summary, LOFT is a proposed X-ray space observatory that has the potential to make significant contributions to our understanding of the universe. It is designed to study the high-energy X-ray emission from compact objects such as neutron stars and black holes, and could provide insights into the behavior of matter under extreme conditions. While the mission is currently on hold due to budget constraints, if and when it is launched, it could help to answer some of the most fundamental questions in astrophysics and cosmology.