Friday, July 21, 2017

A Spiral Galaxy's Central Black Hole's Mass Is Accurately Measured By Its Spiral Arms

After carefully analysing a larger sample of galaxies, imaged by an array of space telescopes, the researchers observed an unexpectedly strong relationship, and one which predicts lower mass black holes in galaxies with open spiral arms (types Sc and Sd). 
"The strength of the correlation is competitive with, if not better than, all our other methods used to predict black hole masses," says Dr Davis. "Anyone can now look at an image of a spiral galaxy and immediately gauge how massive its black hole should be."
From here.  The source and its abstract are as follows:
We have conducted an image analysis of the (current) full sample of 44 spiral galaxies with directly measured supermassive black hole (SMBH) masses, MBH, to determine each galaxy’s logarithmic spiral arm pitch angle, ϕ. For predicting black hole masses, we have derived the relation: log (MBH/M⊙) = (7.01 ± 0.07) − (0.171 ± 0.017)[|ϕ| − 15°]. The total root mean square scatter associated with this relation is 0.43 dex in the log MBH direction, with an intrinsic scatter of 0.30 ± 0.08 dex. The MBH–ϕ relation is therefore at least as accurate at predicting SMBH masses in spiral galaxies as the other known relations. By definition, the existence of an MBH–ϕ relation demands that the SMBH mass must correlate with the galaxy discs in some manner. Moreover, with the majority of our sample (37 of 44) classified in the literature as having a pseudobulge morphology, we additionally reveal that the SMBH mass correlates with the large-scale spiral pattern and thus the discs of galaxies hosting pseudobulges. Furthermore, given that the MBH–ϕ relation is capable of estimating black hole masses in bulge-less spiral galaxies, it therefore has great promise for predicting which galaxies may harbour intermediate-mass black holes (IMBHs, MBH < 105 M⊙). Extrapolating from the current relation, we predict that galaxies with |ϕ| ≥ 26°7' should possess IMBHs.
Benjamin L. Davis, Alister W. Graham, Marc S. Seigar. "Updating the (Supermassive Black Hole Mass) – (Spiral Arm Pitch Angle) Relation: A Strong Correlation for Galaxies with Pseudobulges." Monthly Notices of the Royal Astronomical Society (July 19, 2017) DOI: 10.1093/mnras/stx1794

New Observations Disfavor Fuzzy Dark Matter

Observations of the absorption of photons by neutral hydrogen in deep space strongly disfavor a new dark matter theory called "Fuzzy Dark Matter" while being consistent with the Cold Dark Matter hypothesis (that is itself disfavored by smaller scale structure observations by astronomers). 

In the Fuzzy Dark Matter (FDM) model, dark matter is deemed composed of ultralight bosons provided with a non-negligible pressure at small scales, and  dark matter has higher particle velocities than it does in cold dark matter (CDM) models. FDM models overlap with Axion Dark Matter models.

More Evidence Of Archaic Admixture In Africa

Scientists have located a gene in some sub-Saharan Africans that governs salvia consistency, which is absent from other modern humans (in and out of Africa), form Neanderthals and from Denisovans. 

Given the extent to which it is divergent, the most likely explanation, which supported by other previous research indicating genetic traces of archaic admixture in Africans, is that the ancestors of the people who bear this gene had children with to be determined archaic hominin species in Africa. But, since we have no ancient DNA from any archaic hominin species in Africa, it is hard to know which archaic hominin species introgressed into the modern human genome in Africa.

There Have Been A Small Number Of People With Blue Skin

There is a recessive genetic condition that causes people to have blue tinted skin and purple lips, but because it is rare, it ordinarily isn't observed outside inbred communities such as one that existed in the early to mid-20th century in Eastern Kentucky in the Fugate family. These people were known as the Blue Fugates.
The Fugate family first settled in Kentucky in 1820. Martin Fugate and his wife Elizabeth Smith came to Troublesome Creek, an out-of-the-way region of Appalachia. According to some sources, Fugate was blue himself, though this has been disputed. Whatever his color, his offspring ended up with an unusual appearance: his son Zachariah was born with blue skin, and so were three more of their seven children. . . . 
The Fugates had a genetic defect that resulted in a condition called methemoglobinemia, which means their blood didn't carry as much oxygen around the body. This makes the blood darker, which in turn causes the skin of white people to appear blue, and their lips to look purple. In addition, arterial blood looks chocolate brown rather than red. People with methemoglobinemia have higher levels of methemoglobin in their blood; they may have 10-20 percent, versus the average person's one percent. The Fugates' very blood was different from that of their neighbors. . . . Methemoglobinemia can cause developmental delay and seizures, but despite the intense appearance of their blue skin and purple lips, none of the Fugates suffered poor health or lived in pain. The condition had only a cosmetic effect, though the family endured psychological pain from their outsider status. Each of the Blue Fugates lived to a ripe old age. . . .

After interviewing the Fugates, Cawein concluded that their blood must be missing a crucial enzyme. To trigger the blood's natural processes, the doctor decided to inject the affected family members with methylene blue, a dye. The cosmetic results were nearly instant. Talking about the experience years later, Cawein said that the treated family members were thrilled to see the blue fade from their skin: "For the first time in their lives, they were pink." The solution really was that easy. The effects of the dye were temporary, but Cawein supplied the Fugates with methylene blue tablets to take every day.
The conditions was particularly stigmatizing because it was understood to be connected with undue inbreeding (which was, in fact, present in the family).

Thursday, July 20, 2017

Understanding The Lightest Scalar Mesons

The introduction to a new paper on the photo-production of the two lightest scalar mesons (the f0(500) and the f0(980) explains the still unsolved mystery of these composite hadrons:
Understanding the structure of low-lying scalar mesons has been one of the most challenging issues in hadronic physics. Their internal structure is still under debate. That the f0(500) scalar meson, which is also known as σ, is not an ordinary meson consisting of a quark and an anti-quark is more or less in consensus. Recent studies suggest that these scalar mesons may belong to the flavor SU(3) non-qq¯ nonet (see reviews [1, 2], a “note on scalar mesons below 2 GeV ” in Ref. [3], and references therein. A recent review provides also various information on the structure of the scalar meson [4], including a historical background of the σ meson). The f0(500) is also interepreted as one of the glueballs or gluonia, mixed with the ¯qq state [5–7], though this idea is criticized because the same analysis is rather difficult to be applied to explaining the strange scalar meson K∗ 0 (800) or κ, which is also considered as a member of the nonet. The f0(500) is often regarded as a tetraquark state in a broad sense [8]. The f0(500) as a tetraquark state has a multiple meaning: It can be described as a diquark-antidiquark correlated state [9, 10], ¯qqqq¯ state [11], or correlated 2π state [12, 13] arising from ππ scattering. This non ¯qq feature was employed in various theoretical approaches such as QCD sum rules [14], effective Lagrangians [15], and lattice QCD [16–18].  
The scalar mesons were also extensively studied phenomenologically. There are two scalar-isoscalar mesons (I G(J P C ) = 0+(0++)) below 1 GeV, that is, the lowest-lying f0(500) (or σ) and the first excited f0(980). Both the f0(500) and the f0(980) exist in ππ scattering and their pole positions were investigated based on many different processes, for example, such as πN → ππN reactions [19–21], Kl4 decay [22, 23], D → 3π [24, 25], J/ψ → ωππ [26], ψ(2S) → π +π −J/ψ [27], γγ → ππ [28], pp scattering [29], and so on (for details, we refer to Refs. [3, 4]). While the mass and the width of the f0(980) are more or less known to be mf0 = 990±20 MeV and Γ = 40−100 MeV, those of f0(500) are still far from consensus (see Ref. [3]). The upper bound of the f0(500) mass is given in the large Nc limit in terms of the Gasser-Leutwyler low-energy constant [30], which suggests that the f0 mass is quite possibly smaller than 700 MeV.