Pixel lensing

Novati, S. Calchi

doi:10.1007/s10714-009-0918-3

Cited by 25 publications

(8 citation statements)

References 107 publications

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“…There have also been searches for 'pixel-lensing' in M31 where unresolved stars are being microlensed causing a pixel to brighten. About 30 possible microlensing events have been detected [97], but there is still some debate as to the extent to which self-lensing distorts the statistics [98]. There does however seem to be a good case for around 25% of the M31 halo to be in the form of compact bodies [99,100].…”

Section: Appendix A: Microlensing Constraints and Solar Mass Pbhsmentioning

confidence: 99%

Primordial black holes with an accurate QCD equation of state

Byrnes

Hindmarsh

Young

et al. 2018

J. Cosmol. Astropart. Phys.

198

173

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Making use of definitive new lattice computations of the Standard Model thermodynamics during the quantum chromodynamic (QCD) phase transition, we calculate the enhancement in the mass distribution of primordial black holes (PBHs) due to the softening of the equation of state. We find that the enhancement peaks at approximately 0.7M⊙, with the formation rate increasing by at least two orders of magnitude due to the softening of the equation of state at this time, with a range of approximately 0.3M⊙ < M < 1.4M⊙ at full width half-maximum. PBH formation is increased by a smaller amount for PBHs with masses spanning a large range, 10 −3 M⊙ < MPBH < 10 3 M⊙, which includes the masses of the BHs that LIGO detected. The most significant source of uncertainty in the number of PBHs formed is now due to unknowns in the formation process, rather than from the phase transition. A near scale-invariant density power spectrum tuned to generate a population with mass and merger rate consistent with that detected by LIGO should also produce a much larger energy density of PBHs with solar mass. The existence of BHs below the Chandresekhar mass limit would be a smoking gun for a primordial origin and they could arguably constitute a significant fraction of the cold dark matter density. They also pose a challenge to inflationary model building which seek to produce the LIGO BHs without overproducing lighter PBHs. * C.Byrnes@sussex.ac.uk † m.b.hindmarsh@sussex.ac.uk ‡ S.M.Young@sussex.ac.uk

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Section: Appendix A: Microlensing Constraints and Solar Mass Pbhsmentioning

confidence: 99%

Primordial black holes with an accurate QCD equation of state

Byrnes

Hindmarsh

Young

et al. 2018

J. Cosmol. Astropart. Phys.

198

173

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“…Observations and studies of the pixel‐lensing microlensing events towards M31 are still not conclusive with respect to the amount of SL and MACHO lenses (see Calchi Novati 2010b, for recent review). However, the most recent analysis of the data tends to be inclined towards SL as being the only explanation of the observed signal (Calchi Novati 2010a).…”

Section: Introductionmentioning

confidence: 99%

The OGLE view of microlensing towards the Magellanic Clouds - IV. OGLE-III SMC data and final conclusions on MACHOs★

Wyrzykowski

Skowron

Kozłowski

et al. 2011

Monthly Notices of the Royal Astronomical Society

196

180

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In this fourth part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs), we describe results of the OGLE‐III monitoring of the Small Magellanic Cloud (SMC). Three sound candidates for microlensing events were found and yielded the optical depth τSMC‐OIII= 1.30 ± 1.01 × 10−7, consistent with the expected contribution from Galactic disc and SMC self‐lensing. We report that event OGLE‐SMC‐03 is most likely a thick‐disc lens candidate, the first of such type found towards the SMC. In this paper we also combined all OGLE Large Magellanic Cloud and SMC microlensing results in order to refine the conclusions on MACHOs. All but one of the OGLE events are most likely caused by the lensing by known populations of stars; therefore, we concluded that there is no need for introducing any special dark matter compact objects in order to explain the observed event rates. Potential black hole event indicates that similar lenses can contribute only about 2 per cent to the total mass of the halo, which is still in agreement with the expected number of such objects.

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“…Previously, Ibata et al (1999) and Méndez & Minniti (2000) used the Hubble Deep Field North (Williams et al 1996) and South (Casertano et al 2000) data to constrain the stellar content of the Galaxy. They proposed that the faint blue objects observed in these fields are old halo white dwarfs that would be consistent with the observed microlensing events toward the Large Magellanic Cloud (Alcock et al 2000;Calchi Novati 2010) and would explain part of the dark matter in the solar neighborhood. Kilic et al (2004Kilic et al ( , 2005, Pirzkal et al (2005), and Mahmud & Anderson (2008) showed that some of these faint blue objects are confused with quasars and an extensive study including proper motion measurements and spectral energy distribution (SED) fitting is required to identify stars in deep HST images.…”

Section: Introductionmentioning

confidence: 59%

Moving Objects in the Hubble Ultra Deep Field

Kilic

Gianninas

Hippel

2013

ApJ

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We identify proper motion objects in the Hubble Ultra Deep Field (UDF) using the optical data from the original UDF program in 2004 and the near-infrared data from the 128 orbit UDF 2012 campaign. There are 12 sources brighter than I = 27 mag that display >3σ significant proper motions. We do not find any proper motion objects fainter than this magnitude limit. Combining optical and near-infrared photometry, we model the spectral energy distribution of each point-source using stellar templates and state-of-the-art white dwarf models. For I 27 mag, we identify 23 stars with K0-M6 spectral types and two faint blue objects that are clearly old, thick disk white dwarfs. We measure a thick disk white dwarf space density of 0.1-1.7 × 10 −3 pc −3 from these two objects. There are no halo white dwarfs in the UDF down to I = 27 mag. Combining the Hubble Deep Field North, South, and the UDF data, we do not see any evidence for dark matter in the form of faint halo white dwarfs, and the observed population of white dwarfs can be explained with the standard Galactic models.

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Pixel lensing

Cited by 25 publications

References 107 publications

Primordial black holes with an accurate QCD equation of state

Primordial black holes with an accurate QCD equation of state

The OGLE view of microlensing towards the Magellanic Clouds - IV. OGLE-III SMC data and final conclusions on MACHOs★

Moving Objects in the Hubble Ultra Deep Field

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