该研究提出一种模型无关的搜寻方法，利用射电谱线的多普勒频移和强度分布，在 L 和 S 波段排除了暗物质湮灭和衰变的上限。
摘要：
最一般形式的超轻玻色子暗物质可以通过其衰变或湮灭为一条准单色射电谱线来探测。仅假设这条谱线与我们对银河系晕的预期相空间的最一般性质一致，我们开发并实施了一种新颖的模型无关暗物质搜寻，覆盖 L 和 S 波段。更具体地说，该搜寻选择一条表现出多普勒频移的谱线，其位置随太阳在静态晕中的运动而变化，并且其强度也随相对于银心的位置而变化。在 L 和 S 波段合并的 1020 - 2700 MHz 范围内，暗物质的辐射湮灭被排除在 ⟨σv⟩ ≈ 10⁻³⁰ cm³ s⁻¹ 以上，而衰变则被排除在 λ ≈ 10⁻³² s⁻¹ 以上。
英文摘要：
Ultralight bosonic dark matter in its most general form can be detected through its decay or annihilation to a quasimonochromatic radio line. Assuming only that this line is consistent with the most general properties of the expected phase space of our Milky Way halo, we have developed and carried out a novel model-independent search for dark matter in the L and S bands. More specifically, the search selects for a line that exhibits a Doppler shift with position according to the solar motion through a static halo and similarly varies in intensity with position with respect to the galactic center. Over the combined L- and S-band range 1020 - 2700 MHz, radiative annihilation of dark matter is excluded above $\langleσv\rangle \approx 10^{-30} \text{ cm}^3 \text{ s}^{-1}$, and for decay above $λ\approx 10^{-32} \text{ s}^{-1}$.
A large sample of blazar from the Candidate Gamma Ray Blazar Survey (CGRaBS) has been observed with the Owens Valley Radio Observatory (OVRO) 40-Meter Telescope at 15GHz. Using these quasi-simultaneous observations, we study the connection between the gamma-ray behavior of blazars as detected by Fermi-LAT and the cm band as observed by the F-GAMMA project with the OVRO 40-Meter Telescope. Comparing the light curves for a large number of sources, it is possible to study in detail the relation between the gamma-ray and radio activity of Fermi-LAT detected gamma-ray blazars. We present first resu…
This paper summarizes the design process and metrics for the latest antenna design for 2 radio telescopes, SKALA4 for the SKA1-LOW instrument and the V-feed for the HERA telescope. In the paper we briefly describe the main features of the antenna element design and the most important figures of merit for both instruments. Finally, we show the response of both designs against some of these figures of merit.
We study the conditions for the adiabatic resonant conversion of the cold dark matter (CDM) axions into photons in existence of the astrophysically sourced strong magnetic fields such as those in the neutron star magnetosphere. We demonstrate the possibility that the forthcoming radio telescopes such as the SKA (Square Kilometre Array) can probe those photon signals from the CDM axions.
BINGO is a novel single-dish total-power telescope that will map the redshifted HI sky in a ~15 degree strip, at frequencies of 960-1260 MHz (z=0.12-0.48). BINGO will have the sensitivity to accurately measure the HI power spectrum and to detect Baryon Acoustic Oscillations (BAOs) for the first time at radio wavelengths. This will provide complementary cosmological information to existing surveys and will measure the acoustic scale to ~2 % precision. We provide an update on BINGO including an improved two-mirror optical configuration, final site selection and foreground removal simulations.
The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study va…
We present 610 MHz spectropolarimetric images from the Giant Metrewave Radio Telescope (GMRT). We discuss the properties of the GMRT's full-polarisation mode in detail and provide a technical characterisation of the instrument's polarisation performance. We show that the telescope can be used for wide-field spectropolarimetry. The application of Rotation Measure Synthesis results in a sensitivity at the level of tens of micro-Jy in Faraday space. As a demonstration of the instrument's capabilities, we present observations of two Southern Compact Groups - the Grus Quartet and USCG S063. The obs…
We present a multi-frequency far-field beam map for the 5m dish telescope at the Bleien Observatory measured using a commercially available drone. We describe the hexacopter drone used in this experiment, the design of the flight pattern, and the data analysis scheme. This is the first application of this calibration method to a single dish radio telescope in the far-field. The high signal-to-noise data allows us to characterise the beam pattern with high accuracy out to at least the 4th side-lobe. The resulting 2D beam pattern is compared with that derived from a more traditional calibration …
Neutral hydrogen clouds are known to exist in the Universe, however their spatial distributions and physical properties are poorly understood. Such missing information can be studied by the new generation Chinese radio telescopes through a blind searching of 21-cm absorption systems. We forecast the capabilities of surveys of 21-cm absorption systems by two representative radio telescopes in China -- Five-hundred-meter Aperture Spherical radio Telescope (FAST) and Tianlai 21-cm cosmology experiment (Tianlai). Facilitated by either the high sensitivity (FAST) or the wide field of view (Tianlai)…
Dwarf spheroidal galaxies have long been discussed as optimal targets for indirect dark matter searches. However, the majority of such studies have been conducted with gamma-ray instruments. In this review, we discuss the very recent progress that has been made in radio-based indirect dark matter searches. We look at existing work on this topic and discuss the future prospects that motivate continued work in this newly developing field that promises to become, in the light of the up-coming Square Kilometre Array, a prominent component of the hunt for dark matter.
Dark energy is an important science driver of many upcoming large-scale surveys. With small, stable seeing and low thermal infrared background, Dome A, Antarctica, offers a unique opportunity for shedding light on fundamental questions about the universe. We show that a deep, high-resolution imaging survey of 10,000 square degrees in \emph{ugrizyJH} bands can provide competitive constraints on dark energy equation of state parameters using type Ia supernovae, baryon acoustic oscillations, and weak lensing techniques. Such a survey may be partially achieved with a coordinated effort of the Kunl…
The ANTARES collaboration is currently operating the largest neutrino detector in the Northern Hemisphere. One of the goals of ANTARES is the search for dark matter in the universe. In this paper, the first results on the search for dark matter in the Sun with ANTARES in its 5 line configuration, as well as sensitivity studies on the dark matter search with the full ANTARES detector and the future cubic-kilometer neutrino telescope studied by the KM3NeT consortium are presented.
We present results from a study of seven large known head-tail radio galaxies based on observations using the Giant Metrewave Radio Telescope at 240 and 610 MHz. These observations are used to study the radio morphologies and distribution of the spectral indices across the sources. The overall morphology of the radio tails of these sources is suggestive of random motions of the optical host around the cluster potential. The presence of the multiple bends an d wiggles in several head-tail sources is possibly due to the precessing radio jets. We find steepening of the spectral index along the ra…
Galaxy redshift surveys using optical telescopes have, in combination with other cosmological probes, enabled precision measurements of the nature of dark energy. We show that radio telescopes are rapidly becoming competitive with optical facilities in spectroscopic surveys of large numbers of galaxies. Two breakthroughs are driving this change. Firstly, individual radio telescopes are more efficient at mapping the sky thanks to the large field-of-view of new phased-array feeds. Secondly, ever more dishes can be correlated in a cost-effective manner with rapid increases in computing power. The…
Synchrotron emission from electron cosmic ray populations can be used to study both cosmic rays physics and WIMP dark matter imprints on radio skymaps. We used available radio data - from MHz to GHz - to analyze the contribution from galactic WIMP annihilations and impose constraints on WIMP observables: annihilation cross section, channel and mass. Depending on the annihilation channel we obtain as competitive bounds as those obtained in FERMI-LAT gamma ray analysis of dwarf satellite galaxies.
Dark Matter and Galaxy Cross-Correlations with the Cherenkov Telescope Array Observatory
Flatiron Institute（平顿研究所）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；University of Chicago, Kavli Institute for Cosmological Physics（芝加哥大学卡弗里宇宙物理学研究所）；University of Nova Gorica, Center for Astrophysics and Cosmology（新戈里察大学天体物理学与宇宙学中心）；Instituto de Física Corpuscular (IFIC), University of Valencia and CSIC（瓦伦西亚大学及西班牙高等科研理事会粒子物理研究所（IFIC））；Dipartimento di Fisica, Università degli Studi di Torino（都灵大学物理系）；INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Torino（意大利国家核物理研究所都灵分部）；INAF – Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Torino（意大利国家天体物理都灵天文台）
I outline the prospects for performing weak lensing studies with the new generation of radio telescopes that are coming online now and in the future. I include a description of a proposed technique to use polarization observations in radio weak lensing analyses which could prove extremely useful for removing a contaminating signal from intrinsic alignments. Ultimately, the Square Kilometre Array promises to be an exceptional instrument for performing weak lensing studies due to the high resolution, large area surveys which it will perform. In the nearer term, the e-MERLIN instrument in the UK …
I give a brief review of a few recent developments and future directions in the search for dark matter using high-energy neutrinos from the Sun. This includes the ability to recast neutrino telescope limits on nuclear scattering of dark matter to arbitrary new theories, and new calculations of the solar atmospheric background relevant to such searches. I also touch on applications to global searches for new physics, and prospects for improving searches for asymmetric dark matter in the Sun.
We constrain the effective theory of one-body dark matter-nucleon interactions using neutrino telescope observations. We derive exclusion limits on the 28 coupling constants of the theory, exploring interaction operators previously considered in dark matter direct detection only, and using new nuclear response functions recently derived through nuclear structure calculations. We determine for what interactions neutrino telescopes are superior to current direct detection experiments, and show that Hydrogen is not the most important element in the exclusion limit calculation for the majority of …
We investigate the use of next generation radio telescopes such as the Square Kilometre Array (SKA) to detect axion two-photon coupling in the astrophysical environment. The uncertainty surrounding astrophysical magnetic fields presents new challenges, but with a frequency range corresponding to axions of mass $1.7-57μ$eV and a spectral profile with a number of distinguishing features, SKA-mid offers a tantalising opportunity to constrain axion dark matter properties. To determine the sensitivity of SKA-mid to an axion signal, we consider observations of the Galactic centre and interstellar me…
Experimental developments in neutrino telescopes are drastically improving their ability to constrain the annihilation cross-section of dark matter. In this paper, we employ an angular power spectrum analysis method to probe the galactic and extra-galactic dark matter signals with neutrino telescopes. We first derive projections for a next generation of neutrino telescope that is inspired by KM3NeT. We emphasise that such analysis is much less sensitive to the choice of dark matter density profile. Remarkably, the projected sensitivity is improved by more than an order of magnitude with respec…
New York University, Abu Dhabi（纽约大学阿布扎比分校）；Department of Theoretical Physics and Gravitational Wave Science Center, 24 quai E. Ansermet, CH-1211 Geneva 4, Switzerland（日内瓦大学理论物理系与引力波科学中心）
Large Observatory For X-ray Timing (LOFT) is a next generation X-ray telescope selected by European Space Agency as one of the space mission concepts within the ``Cosmic Vision'' programme. The Large Area Detector on board of LOFT will be a collimator-type telescope with an unprecedentedly large collecting area of about 10 square meters in the energy band between 2 and 100 keV. We demonstrate that LOFT will be a powerful dark matter detector, suitable for the search of the X-ray line emission expected from decays of light dark matter particles in galactic halos. We show that LOFT will have sen…
We present new limits on early dark energy (EDE) from the cosmic microwave background (CMB) using data from the WMAP satellite on large angular scales and South Pole Telescope (SPT) on small angular scales. We find a strong upper limit on the EDE density of Omega_e < 0.018 at 95% confidence, a factor of three improvement over WMAP data alone. We show that adding lower-redshift probes of the expansion rate to the CMB data improves constraints on the dark energy equation of state, but not the EDE density. We also explain how the small-scale CMB temperature anisotropy constrains EDE.
The first stars in the history of the Universe are likely to form in the dense central regions of 10^5-10^6 Msolar cold dark matter halos at z=10-50. The annihilation of dark matter particles in these environments may lead to the formation of so-called dark stars, which are predicted to be cooler, larger, more massive and potentially more long-lived than conventional population III stars. Here, we investigate the prospects of detecting high-redshift dark stars with the upcoming James Webb Space Telescope (JWST). We find that dark stars at z>6 are intrinsically too faint to be detected by JWST.…
The dark matter subhalo mass function is a promising way of distinguishing between dark matter models. While cold dark matter predicts halos down to Earth-sized masses, other dark matter models typically predict a cut-off in the subhalo mass function. Thus a definitive detection or limits on the existence of subhalos at small masses can give us insight into the nature of dark matter. If these subhalos exist in the Milky Way, they would produce weak lensing signatures, such as modified apparent positions, on background stars. These signatures would generate correlations in the apparent velociti…
The initial data from the Event Horizon Telescope (EHT) on M87$^*$, the supermassive black hole at the center of the M87 galaxy, provide direct observational information on its mass, spin, and accretion disk properties. A combination of the EHT data and other constraints provide evidence that M87$^*$ has a mass $\sim 6.5 \times 10^9\,M_\odot$ and dimensionless spin parameter $|a^*|\gtrsim 0.5$. These determinations disfavor ultra light bosons of mass $μ_b\sim 10^{-21}$ eV, within the range considered for fuzzy dark matter, invoked to explain dark matter distribution on $\sim$ kpc scales. Futur…
We used a consistent and robust solar model to obtain upper limits placed by neutrino telescopes, such as Ice- Cube and Super-Kamiokande, on the Dark Matter-nucleon scattering cross-section, for a general model of Dark Matter with a velocity dependent (p-wave) thermally averaged cross-section. In this picture, the Boltzmann equation for the Dark Matter abundance is numerically solved satisfying the Dark Matter density measured from the Cosmic Microwave Background (CMB). We show that for lower cross-sections and higher masses, the Dark Matter annihilation rate drops sharply, resulting in upper …
We investigate constraints on the distribution of dark matter in the neighbourhood of the Galactic centre that may eventually be attained with the high-resolution Event Horizon Telescope (EHT). The shadow of a black hole in vacuum is used to generate a toy model describing how dark matter affects the size of the shadow of the supermassive black hole located at the Galactic centre. Observations by the EHT may constrain the properties of the dark matter distribution in a possible density spike around the black hole. Current uncertainties due to both the resolution of the telescope and the analys…
