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Constraining Primordial Black Holes with the EDGES 21-cm Absorption Signal
/ Hektor, Andi (NICPB, Tallinn) ; Hütsi, Gert (Tartu U. ; NICPB, Tallinn) ; Marzola, Luca (NICPB, Tallinn) ; Raidal, Martti (CERN ; NICPB, Tallinn) ; Vaskonen, Ville (NICPB, Tallinn) ; Veermäe, Hardi (CERN ; NICPB, Tallinn)
The EDGES experiment has recently measured an anomalous global 21-cm spectrum due to hydrogen absorptions at redshifts of about $z\sim 17$. Model independently, the unusually low temperature of baryons probed by this observable sets strong constraints on any physical process that transfers energy into the baryonic environment at such redshifts. [...]
arXiv:1803.09697; CERN-TH-2018-073.-
2018-07-04 - 7 p.
- Published in : Phys. Rev. D 98 (2018) 023503
Fulltext: PDF; Fulltext from Publisher: PDF;
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2.
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The EDGES 21 cm Anomaly and Properties of Dark Matter
/ Fraser, Sean (NICPB, Tallinn) ; Hektor, Andi (NICPB, Tallinn) ; Hütsi, Gert (NICPB, Tallinn) ; Kannike, Kristjan (NICPB, Tallinn) ; Marzo, Carlo (NICPB, Tallinn) ; Marzola, Luca (NICPB, Tallinn) ; Spethmann, Christian (NICPB, Tallinn) ; Racioppi, Antonio (NICPB, Tallinn) ; Raidal, Martti (CERN ; NICPB, Tallinn) ; Vaskonen, Ville (NICPB, Tallinn) et al.
The recently claimed anomaly in the measurement of the 21 cm hydrogen absorption signal by EDGES at $z\sim 17$, if cosmological, requires the existence of new physics. The possible attempts to resolve the anomaly rely on either (i) cooling the hydrogen gas via new dark matter-hydrogen interactions or (ii) modifying the soft photon background beyond the standard CMB one, as possibly suggested also by the ARCADE~2 excess. [...]
arXiv:1803.03245; CERN-TH-2018-053.-
2018-10-10 - 6 p.
- Published in : Phys. Lett. B 785 (2018) 159-164
Article from SCOAP3: PDF; Fulltext: PDF;
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3.
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Search for Dark Matter Effects on Gravitational Signals from Neutron Star Mergers
/ Ellis, John (NICPB, Tallinn ; CERN ; King's Coll. London) ; Hektor, Andi (NICPB, Tallinn) ; Hütsi, Gert (NICPB, Tallinn ; Tartu Observ.) ; Kannike, Kristjan (NICPB, Tallinn) ; Marzola, Luca (NICPB, Tallinn) ; Raidal, Martti (NICPB, Tallinn) ; Vaskonen, Ville (NICPB, Tallinn)
Motivated by the recent detection of the gravitational wave signal emitted by a binary neutron star merger, we analyse the possible impact of dark matter on such signals. We show that dark matter cores in merging neutron stars may yield an observable supplementary peak in the gravitational wave power spectral density following the merger, which could be distinguished from the features produced by the neutron components..
arXiv:1710.05540; CERN-TH-2017-208; KCL-PH-TH-2017-50.-
2018-06-10 - 4 p.
- Published in : Phys. Lett. B 781 (2018) 607-610
Article from SCOAP3: PDF; Fulltext: PDF;
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Gravitational Waves from SMBH Binaries in Light of the NANOGrav 15-Year Data
/ Ellis, John (Unlisted, EE ; King's Coll. London ; CERN) ; Fairbairn, Malcolm (King's Coll. London) ; Hütsi, Gert (Unlisted, EE) ; Raidal, Juhan (Unlisted, EE) ; Urrutia, Juan (Unlisted, EE ; NICPB, Tallinn) ; Vaskonen, Ville (Unlisted, EE ; Padua U. ; INFN, Padua) ; Veermäe, Hardi (Unlisted, EE)
The NANOGrav Collaboration has recently announced evidence for nHz gravitational waves (GWs), in the form of a Hellings-Downs angular correlation in the common-spectrum process that had been observed previously by them and other Pulsar Timing Arrays (PTAs). We analyze the possibility that these GWs originate from binary supermassive black holes (SMBHs) with total masses $\gtrsim 10^9\, M_{\odot}$. [...]
arXiv:2306.17021; KCL-PH-TH/2023-37; CERN-TH-2023-120; AION-REPORT/2023-06.-
2024-01-10 - 11 p.
- Published in : Phys. Rev. D 109 (2024) L021302
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6.
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Wormholes in conformal gravity
/ Hohmann, Manuel (Tartu, Inst. Phys.) ; Pfeifer, Christian (Tartu, Inst. Phys.) ; Raidal, Martti (NICPB, Tallinn) ; Veermäe, Hardi (NICPB, Tallinn ; CERN)
We present a new class of solutions for static spherically symmetric wormhole spacetimes in conformal gravity and outline a detailed method for their construction. As an explicit example, we construct a class of traversable and non-traversable wormholes that are locally conformal to Schwarzschild-(anti) de Sitter spacetimes. [...]
arXiv:1802.02184; CERN-TH-2018-026.-
2018-10-01 - 24 p.
- Published in : JCAP 10 (2018) 003
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7.
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What is the source of the PTA GW signal?
/ Ellis, John (NICPB, Tallinn ; King's Coll. London ; CERN) ; Fairbairn, Malcolm (King's Coll. London) ; Franciolini, Gabriele (Rome U. ; INFN, Rome) ; Hütsi, Gert (NICPB, Tallinn) ; Iovino, Antonio (NICPB, Tallinn ; Rome U. ; INFN, Rome) ; Lewicki, Marek (Warsaw U.) ; Raidal, Martti (NICPB, Tallinn) ; Urrutia, Juan (NICPB, Tallinn ; Tallinn U. Tech.) ; Vaskonen, Ville (NICPB, Tallinn ; Padua U. ; INFN, Padua) ; Veermäe, Hardi (NICPB, Tallinn)
The most conservative interpretation of the nHz stochastic gravitational wave background (SGWB) discovered by NANOGrav and other Pulsar Timing Array (PTA) Collaborations is astrophysical, namely that it originates from supermassive black hole (SMBH) binaries. However, alternative cosmological models have been proposed, including cosmic strings, phase transitions, domain walls, primordial fluctuations and "audible" axions. [...]
arXiv:2308.08546; KCL-PH-TH/2023-43; CERN-TH-2023-153; AION-REPORT/2023-08.-
2024-01-15 - 22 p.
- Published in : Phys. Rev. D 109 (2024) 023522
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8.
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Dark Matter Effects On Neutron Star Properties
/ Ellis, John (NICPB, Tallinn ; King's Coll. London ; CERN) ; Hütsi, Gert (NICPB, Tallinn ; Tartu U.) ; Kannike, Kristjan (NICPB, Tallinn) ; Marzola, Luca (NICPB, Tallinn) ; Raidal, Martti (NICPB, Tallinn) ; Vaskonen, Ville (NICPB, Tallinn)
We study possible effects of a dark matter (DM) core on the maximum mass of a neutron star (NS), on the mass-radius relation and on the NS tidal deformability parameter $\Lambda$. We show that all these quantities would in general be reduced in the presence of a DM core. [...]
arXiv:1804.01418; CERN-TH-2018-072; KCL-PH-TH/2018-13; KCL-PH-TH-2018-13.-
2018-06-15 - 7 p.
- Published in : Phys. Rev. D 97 (2018) 123007
Article from SCOAP3: PDF; Fulltext: PDF;
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9.
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Consistency of JWST Black Hole Observations with NANOGrav Gravitational Wave Measurements
/ Ellis, John (King's Coll. London ; CERN) ; Fairbairn, Malcolm (King's Coll. London) ; Hütsi, Gert (Unlisted, EE) ; Urrutia, Juan (Unlisted, EE ; NICPB, Tallinn) ; Vaskonen, Ville (Unlisted, EE ; Padua U. ; INFN, Padua) ; Veermäe, Hardi (Unlisted, EE)
JWST observations have opened a new chapter in studies of supermassive black holes (SMBHs), stimulating discussion of two puzzles: the abundance of SMBHs in the early Universe and the fraction of dual AGNs. In this paper we argue that the answers to these puzzles may be linked to an interpretation of the data on the nHz gravitational wave (GWs) discovered by NANOGrav and other Pulsar Timing Arrays (PTAs) in terms of SMBH binaries losing energy by interactions with their environments as well as by GW emission. [...]
arXiv:2403.19650; KCL-PH-TH/2024-16; CERN-TH-2024-038; AION-REPORT/2024-03.-
2024-09-30 - 9 p.
- Published in : Astron. Astrophys. 691 (2024) A270
Fulltext: 2403.19650 - PDF; Publication - PDF;
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A lower bound on the primordial black hole merger rate
/ Vaskonen, Ville (King's Coll. London ; NICPB, Tallinn) ; Veermäe, Hardi (NICPB, Tallinn ; CERN)
We derive a lower bound on the merger rate of primordial black hole (PBH) binaries by estimating the maximal fraction of binaries that were perturbed between formation in the early Universe and merger, and computing a conservative merger rate of perturbed binaries. This implies robust constraints on the PBH abundance in the range $1-100 M_\odot$. [...]
arXiv:1908.09752; CERN-TH-2019-141; KCL-PH-TH/2019-69.-
2020-02-20 - 8 p.
- Published in : Phys. Rev. D 101 (2020) 043015
Fulltext: 1908.09752 - PDF; PhysRevD.101.043015 - PDF; Fulltext from Publisher: PDF;
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