Colloquium: Measuring the neutron star equation of state using x-ray timing
One of the primary science goals of the next generation of hard x-ray timing instruments is to determine the equation of state of matter at supranuclear densities inside neutron stars by measuring the radius of neutron stars with different masses to accuracies of a few percent. Three main techniques...
| Main Authors: | , , , , , , , , , , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Published: |
American Physical Society (APS)
2018
|
| Online Access: | http://hdl.handle.net/1721.1/117028 https://orcid.org/0000-0001-8804-8946 |
| _version_ | 1811073460066058240 |
|---|---|
| author | Watts, Anna L. Andersson, Nils Chakrabarty, Deepto Feroci, Marco Hebeler, Kai Israel, Gianluca Lamb, Frederick K. Miller, M. Coleman Morsink, Sharon Özel, Feryal Patruno, Alessandro Poutanen, Juri Psaltis, Dimitrios Schwenk, Achim Steiner, Andrew W. Stella, Luigi Tolos, Laura van der Klis, Michiel |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Watts, Anna L. Andersson, Nils Chakrabarty, Deepto Feroci, Marco Hebeler, Kai Israel, Gianluca Lamb, Frederick K. Miller, M. Coleman Morsink, Sharon Özel, Feryal Patruno, Alessandro Poutanen, Juri Psaltis, Dimitrios Schwenk, Achim Steiner, Andrew W. Stella, Luigi Tolos, Laura van der Klis, Michiel |
| author_sort | Watts, Anna L. |
| collection | MIT |
| description | One of the primary science goals of the next generation of hard x-ray timing instruments is to determine the equation of state of matter at supranuclear densities inside neutron stars by measuring the radius of neutron stars with different masses to accuracies of a few percent. Three main techniques can be used to achieve this goal. The first involves waveform modeling. The flux observed from a hotspot on the neutron star surface offset from the rotational pole will be modulated by the star's rotation, and this periodic modulation at the spin frequency is called a pulsation. As the photons propagate through the curved spacetime of the star, information about mass and radius is encoded into the shape of the waveform (pulse profile) via special and general-relativistic effects. Using pulsations from known sources (which have hotspots that develop either during thermonuclear bursts or due to channeled accretion) it is possible to obtain tight constraints on mass and radius. The second technique involves characterizing the spin distribution of accreting neutron stars. A large collecting area enables highly sensitive searches for weak or intermittent pulsations (which yield spin) from the many accreting neutron stars whose spin rates are not yet known. The most rapidly rotating stars provide a clean constraint, since the limiting spin rate where the equatorial surface velocity is comparable to the local orbital velocity, at which mass shedding occurs, is a function of mass and radius. However, the overall spin distribution also provides a guide to the torque mechanisms in operation and the moment of inertia, both of which can depend sensitively on dense matter physics. The third technique is to search for quasiperiodic oscillations in x-ray flux associated with global seismic vibrations of magnetars (the most highly magnetized neutron stars), triggered by magnetic explosions. The vibrational frequencies depend on stellar parameters including the dense matter equation of state, and large-area x-ray timing instruments would provide much improved detection capability. An illustration is given of how these complementary x-ray timing techniques can be used to constrain the dense matter equation of state and the results that might be expected from a 10 m2 instrument are discussed. Also discussed are how the results from such a facility would compare to other astronomical investigations of neutron star properties. |
| first_indexed | 2024-09-23T09:33:27Z |
| format | Article |
| id | mit-1721.1/117028 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T09:33:27Z |
| publishDate | 2018 |
| publisher | American Physical Society (APS) |
| record_format | dspace |
| spelling | mit-1721.1/1170282022-09-26T12:14:55Z Colloquium: Measuring the neutron star equation of state using x-ray timing Watts, Anna L. Andersson, Nils Chakrabarty, Deepto Feroci, Marco Hebeler, Kai Israel, Gianluca Lamb, Frederick K. Miller, M. Coleman Morsink, Sharon Özel, Feryal Patruno, Alessandro Poutanen, Juri Psaltis, Dimitrios Schwenk, Achim Steiner, Andrew W. Stella, Luigi Tolos, Laura van der Klis, Michiel Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Chakrabarty, Deepto One of the primary science goals of the next generation of hard x-ray timing instruments is to determine the equation of state of matter at supranuclear densities inside neutron stars by measuring the radius of neutron stars with different masses to accuracies of a few percent. Three main techniques can be used to achieve this goal. The first involves waveform modeling. The flux observed from a hotspot on the neutron star surface offset from the rotational pole will be modulated by the star's rotation, and this periodic modulation at the spin frequency is called a pulsation. As the photons propagate through the curved spacetime of the star, information about mass and radius is encoded into the shape of the waveform (pulse profile) via special and general-relativistic effects. Using pulsations from known sources (which have hotspots that develop either during thermonuclear bursts or due to channeled accretion) it is possible to obtain tight constraints on mass and radius. The second technique involves characterizing the spin distribution of accreting neutron stars. A large collecting area enables highly sensitive searches for weak or intermittent pulsations (which yield spin) from the many accreting neutron stars whose spin rates are not yet known. The most rapidly rotating stars provide a clean constraint, since the limiting spin rate where the equatorial surface velocity is comparable to the local orbital velocity, at which mass shedding occurs, is a function of mass and radius. However, the overall spin distribution also provides a guide to the torque mechanisms in operation and the moment of inertia, both of which can depend sensitively on dense matter physics. The third technique is to search for quasiperiodic oscillations in x-ray flux associated with global seismic vibrations of magnetars (the most highly magnetized neutron stars), triggered by magnetic explosions. The vibrational frequencies depend on stellar parameters including the dense matter equation of state, and large-area x-ray timing instruments would provide much improved detection capability. An illustration is given of how these complementary x-ray timing techniques can be used to constrain the dense matter equation of state and the results that might be expected from a 10 m2 instrument are discussed. Also discussed are how the results from such a facility would compare to other astronomical investigations of neutron star properties. 2018-07-20T15:22:58Z 2018-07-20T15:22:58Z 2016-04 2018-05-08T14:05:50Z Article http://purl.org/eprint/type/JournalArticle 0034-6861 1539-0756 http://hdl.handle.net/1721.1/117028 Watts, Anna L., et al. “Colloquium : Measuring the Neutron Star Equation of State Using x-Ray Timing.” Reviews of Modern Physics, vol. 88, no. 2, Apr. 2016. © 2016 American Physical Society https://orcid.org/0000-0001-8804-8946 http://dx.doi.org/10.1103/REVMODPHYS.88.021001 Reviews of Modern Physics Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Physical Society (APS) APS |
| spellingShingle | Watts, Anna L. Andersson, Nils Chakrabarty, Deepto Feroci, Marco Hebeler, Kai Israel, Gianluca Lamb, Frederick K. Miller, M. Coleman Morsink, Sharon Özel, Feryal Patruno, Alessandro Poutanen, Juri Psaltis, Dimitrios Schwenk, Achim Steiner, Andrew W. Stella, Luigi Tolos, Laura van der Klis, Michiel Colloquium: Measuring the neutron star equation of state using x-ray timing |
| title | Colloquium: Measuring the neutron star equation of state using x-ray timing |
| title_full | Colloquium: Measuring the neutron star equation of state using x-ray timing |
| title_fullStr | Colloquium: Measuring the neutron star equation of state using x-ray timing |
| title_full_unstemmed | Colloquium: Measuring the neutron star equation of state using x-ray timing |
| title_short | Colloquium: Measuring the neutron star equation of state using x-ray timing |
| title_sort | colloquium measuring the neutron star equation of state using x ray timing |
| url | http://hdl.handle.net/1721.1/117028 https://orcid.org/0000-0001-8804-8946 |
| work_keys_str_mv | AT wattsannal colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT anderssonnils colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT chakrabartydeepto colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT ferocimarco colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT hebelerkai colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT israelgianluca colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT lambfrederickk colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT millermcoleman colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT morsinksharon colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT ozelferyal colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT patrunoalessandro colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT poutanenjuri colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT psaltisdimitrios colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT schwenkachim colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT steinerandreww colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT stellaluigi colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT toloslaura colloquiummeasuringtheneutronstarequationofstateusingxraytiming AT vanderklismichiel colloquiummeasuringtheneutronstarequationofstateusingxraytiming |