7 research outputs found
Testing general relativity and probing the merger history of massive black holes with LISA
Observations of binary inspirals with LISA will allow us to place bounds on
alternative theories of gravity and to study the merger history of massive
black holes (MBH). These possibilities rely on LISA's parameter estimation
accuracy. We update previous studies of parameter estimation including
non-precessional spin effects. We work both in Einstein's theory and in
alternative theories of gravity of the scalar-tensor and massive-graviton
types. Inclusion of non-precessional spin terms in MBH binaries has little
effect on the angular resolution or on distance determination accuracy, but it
degrades the estimation of the chirp mass and reduced mass by between one and
two orders of magnitude. The bound on the coupling parameter of scalar-tensor
gravity is significantly reduced by the presence of spin couplings, while the
reduction in the graviton-mass bound is milder. LISA will measure the
luminosity distance of MBHs to better than ~10% out to z~4 for a (10^6+10^6)
Msun binary, and out to z~2 for a (10^7+10^7) Msun binary. The chirp mass of a
MBH binary can always be determined with excellent accuracy. Ignoring spin
effects, the reduced mass can be measured within ~1% out to z=10 and beyond for
a (10^6+10^6) Msun binary, but only out to z~2 for a (10^7+10^7) Msun binary.
Present-day MBH coalescence rate calculations indicate that most detectable
events should originate at z~2-6: at these redshifts LISA can be used to
measure the two black hole masses and their luminosity distance with sufficient
accuracy to probe the merger history of MBHs. If the low-frequency LISA noise
can only be trusted down to 10^-4 Hz, parameter estimation for MBHs (and LISA's
ability to perform reliable cosmological observations) will be significantly
degraded.Comment: 13 pages, 4 figures. Proceedings of GWDAW 9. Matches version accepted
in Classical and Quantum Gravit
Dark Matter Annihilation around Intermediate Mass Black Holes: an update
The formation and evolution of Black Holes inevitably affects the
distribution of dark and baryonic matter in the neighborhood of the Black Hole.
These effects may be particularly relevant around Supermassive and Intermediate
Mass Black Holes (IMBHs), the formation of which can lead to large Dark Matter
overdensities, called {\em spikes} and {\em mini-spikes} respectively. Despite
being larger and more dense, spikes evolve at the very centers of galactic
halos, in regions where numerous dynamical effects tend to destroy them.
Mini-spikes may be more likely to survive, and they have been proposed as
worthwhile targets for indirect Dark Matter searches. We review here the
formation scenarios and the prospects for detection of mini-spikes, and we
present new estimates for the abundances of mini-spikes to illustrate the
sensitivity of such predictions to cosmological parameters and uncertainties
regarding the astrophysics of Black Hole formation at high redshift. We also
connect the IMBHs scenario to the recent measurements of cosmic-ray electron
and positron spectra by the PAMELA, ATIC, H.E.S.S., and Fermi collaborations.Comment: 12 pages, 7 figures. Invited contribution to NJP Focus Issue on "Dark
Matter and Particle Physics
Strong gravitational lensing probes of the particle nature of dark matter
There is a vast menagerie of plausible candidates for the constituents of
dark matter, both within and beyond extensions of the Standard Model of
particle physics. Each of these candidates may have scattering (and other)
cross section properties that are consistent with the dark matter abundance,
BBN, and the most scales in the matter power spectrum; but which may have
vastly different behavior at sub-galactic "cutoff" scales, below which dark
matter density fluctuations are smoothed out. The only way to quantitatively
measure the power spectrum behavior at sub-galactic scales at distances beyond
the local universe, and indeed over cosmic time, is through probes available in
multiply imaged strong gravitational lenses. Gravitational potential
perturbations by dark matter substructure encode information in the observed
relative magnifications, positions, and time delays in a strong lens. Each of
these is sensitive to a different moment of the substructure mass function and
to different effective mass ranges of the substructure. The time delay
perturbations, in particular, are proving to be largely immune to the
degeneracies and systematic uncertainties that have impacted exploitation of
strong lenses for such studies. There is great potential for a coordinated
theoretical and observational effort to enable a sophisticated exploitation of
strong gravitational lenses as direct probes of dark matter properties. This
opportunity motivates this white paper, and drives the need for: a) strong
support of the theoretical work necessary to understand all astrophysical
consequences for different dark matter candidates; and b) tailored
observational campaigns, and even a fully dedicated mission, to obtain the
requisite data.Comment: Science white paper submitted to the Astro2010 Decadal Cosmology &
Fundamental Physics Science Frontier Pane
Probing the Fundamental Nature of Dark Matter with the Large Synoptic Survey Telescope
94 pages, 22 figures, 1 tableAstrophysical and cosmological observations currently provide the only robust, empirical measurements of dark matter. Future observations with Large Synoptic Survey Telescope (LSST) will provide necessary guidance for the experimental dark matter program. This white paper represents a community effort to summarize the science case for studying the fundamental physics of dark matter with LSST. We discuss how LSST will inform our understanding of the fundamental properties of dark matter, such as particle mass, self-interaction strength, non-gravitational couplings to the Standard Model, and compact object abundances. Additionally, we discuss the ways that LSST will complement other experiments to strengthen our understanding of the fundamental characteristics of dark matter. More information on the LSST dark matter effort can be found at https://lsstdarkmatter.github.io/
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Probing the Fundamental Nature of Dark Matter with the Large Synoptic Survey Telescope
Astrophysical and cosmological observations currently provide the only
robust, empirical measurements of dark matter. Future observations with Large
Synoptic Survey Telescope (LSST) will provide necessary guidance for the
experimental dark matter program. This white paper represents a community
effort to summarize the science case for studying the fundamental physics of
dark matter with LSST. We discuss how LSST will inform our understanding of the
fundamental properties of dark matter, such as particle mass, self-interaction
strength, non-gravitational couplings to the Standard Model, and compact object
abundances. Additionally, we discuss the ways that LSST will complement other
experiments to strengthen our understanding of the fundamental characteristics
of dark matter. More information on the LSST dark matter effort can be found at
https://lsstdarkmatter.github.io/
Dark Matter Science in the Era of LSST
Astrophysical observations currently provide the only robust, empirical measurements of dark matter. In the coming decade, astrophysical observations will guide other experimental efforts, while simultaneously probing unique regions of dark matter parameter space. This white paper summarizes astrophysical observations that can constrain the fundamental physics of dark matter in the era of LSST. We describe how astrophysical observations will inform our understanding of the fundamental properties of dark matter, such as particle mass, self-interaction strength, non-gravitational interactions with the Standard Model, and compact object abundances. Additionally, we highlight theoretical work and experimental/observational facilities that will complement LSST to strengthen our understanding of the fundamental characteristics of dark matter