Letter from John Muir to Louie [Wanda and Helen Muir], [ca. 1905 Jun].

[letterhead]Sunday, 1905Dear Louie & darlingsI arrived at the fine Lummis home about 8 o\u27clock this morning & feel at home, but have not yet been able to decide on a place for our first camp I am now sending back your pass which I forgot to leave with you. Be very carefule to pin it in a safe 03585 [in margin: the weather is almost cold here. Send letters. should you have to write or telegraph address 200 Avenue 43. Just as I wrote the word Telegraph your telegram was handed in to me]place in traveling I\u27ll let you know the day to start as soon as possible. Nothing will be gained by too great hurry, for I think I can get letters that will be very useful & comforting to us sagebrush orphans from others beside Mr L. We are going to have a grand healing time.Ever loving -Papa J.M. OUT WEST Editor\u27s OfficeLos Angeles, Cal., Sunday, 1905Dear Louie and darlings:I arrived at the fine Lummis home about 8 o\u27clock this morning, and feel at home, but have not yet been able to decide on a place for our first camp. I am now sending back your pass which I forgot to leave with you. Be very careful to pin it in a safe place in traveling. I\u27ll let you know the day I start as soon as possible. Nothing will be gained by too great hurry, for I think I can get letters that will be very useful and comforting to us sage brush orpans [orphans] from others besides Mr. L. We are going to have a grand healing time.Ever loving Papa,J.M.The weather is almost cool here. Send letters, should you have to write or telegraph address 200 Avenue 43. Just as I wrote the word telegraph you telegram was handed to me.0357

Primordial Black Holes as Generators of Cosmic Structures

Primordial black holes (PBHs) could provide the dark matter in various mass windows below $10^2 M_{\odot}$ and those of $30 M_{\odot}$ might explain the LIGO events. PBHs much larger than this might have important consequences even if they provide only a small fraction of the dark matter. In particular, they could generate cosmological structure either individually through through the `seed' effect or collectively through the `Poisson' effect, thereby alleviating some problems associated with the standard CDM scenario. If the PBHs all have a similar mass and make a small contribution to the dark matter, then the seed effect dominates on small scales, in which case PBHs could seed the supermassive black holes in galactic nuclei or even galaxies themselves. If they have a similar mass and provide the dark matter, the Poisson effect dominates on all scales and the first bound clouds would form earlier than in the usual scenario, with interesting observational consequences. If the PBHs have an extended mass spectrum, which is more likely, they could fulfill all three roles - providing the dark matter, binding the first bound clouds and generating galaxies. In this case, the galactic mass function naturally has the observed form, with the galaxy mass being simply related to the black hole mass. The stochastic gravitational wave background from the PBHs in this scenario would extend continuously from the LIGO frequency to the LISA frequency, offering a potential goal for future surveys.Comment: 48 pages, 3 figures, accepted for publication in Monthly Notices of Royal Astronomical Societ

A new method for the estimate of H_0 from quadruply imaged gravitational lens systems

We present a new method to estimate the Hubble constant H_0 from the measured time delays in quadruply imaged gravitational lens systems. We show how it is possible to get an estimate of H_0 without the need to completely reconstruct the lensing potential thus avoiding any a priori hypotheses on the expression of the galaxy lens model. Our method only needs to assume that the lens potential may be expressed as r^{\alpha} F(\theta), whatever the shape function F(\theta) is, and it is thus able to fully explore the degeneracy in the mass models taking also into account the presence of an external shear. We test the method on simulated cases and show that it does work well in recovering the correct value of the slope \alpha of the radial profile and of the Hubble constant H_0. Then, we apply the same method to the real quadruple lenses PG1115+080 and B1422+231 obtaining H_0 = 58_{-15}^{+17} km/s/Mpc (68% CL).Comment: 12 pages, 5 figures, accepted for publication on Astronomy & Astrophysic