Constraining Electromagnetic Signals from Black Holes with Hair

We constrain a broad class of "hairy" black hole models capable of directly sourcing electromagnetic radiation during a binary black hole merger. This signal is generic and model-independent since it is characterized by the black hole mass ($M$) and the fraction of that mass released as radiation ($\epsilon$). For field energy densities surpassing the Schwinger limit, this mechanism triggers pair-production to produce a gamma-ray burst. By cross-referencing gravitational wave events with gamma-ray observations, we place upper bounds of $\epsilon<10^{-5}-10^{-4}$ for $10-50$ $M_\odot$ black holes depending on the black hole mass. We discuss the weak detection of a gamma-ray burst following GW150914 and show that this event is consistent with rapid electromagnetic emission directly from a "hairy" black hole with $\epsilon\sim10^{-7}-10^{-6}$. Below the Schwinger limit, ambient charged particles are rapidly accelerated to nearly the speed of light by the strong electromagnetic field. For 1-50 $M_\odot$ black holes and $\epsilon$ ranging from $10^{-20}$ to $10^{-7}$, the typical proton energies are $\sim20$ GeV-20 TeV and electron energies are $\sim0.01-10$ GeV. At these energies, cosmic ray protons and electrons quickly diffuse into the Milky Way's background magnetic field, making it difficult to identify a point source producing them. Overall, constraining $\epsilon$ in this less energetic regime becomes difficult and future constraints may need to consider specific models of "hairy" black holes.Comment: 9 pages, 3 figures, 2 table

Discovery of a proto-white dwarf with a massive unseen companion

We report the discovery of SDSS~J022932.28+713002.7, a nascent extremely low-mass (ELM) white dwarf (WD) orbiting a massive ($> 1\,M_\odot$ at 2$\sigma$ confidence) companion with a period of 36 hours. We use a combination of spectroscopy, including data from the ongoing SDSS-V survey, and photometry to measure the stellar parameters for the primary pre-ELM white dwarf. The lightcurve of the primary WD exhibits ellipsoidal variation, which we combine with radial velocity data and $\tt{PHOEBE}$ binary simulations to estimate the mass of the invisible companion. We find that the primary WD has mass $M_1$ = $0.18^{+0.02}_{-0.02}$ M$_\odot$ and the unseen secondary has mass $M_2$ = $1.19^{+0.21}_{-0.14}$ M$_\odot$. The mass of the companion suggests that it is most likely a near-Chandrasekhar mass white dwarf or a neutron star. It is likely that the system recently went through a Roche lobe overflow from the visible primary onto the invisible secondary. The dynamical configuration of the binary is consistent with the theoretical evolutionary tracks for such objects, and the primary is currently in its contraction phase. The measured orbital period puts this system on a stable evolutionary path which, within a few Gyrs, will lead to a contracted ELM white dwarf orbiting a massive compact companion.Comment: 21 Pages, 8 Figure

Measuring The Mass-Radius Relation of White Dwarfs Using Wide Binaries

Measuring the mass-radius relation of individual white dwarfs is an empirically challenging task that has been performed for only a few dozen stars. We measure the white dwarf mass-radius relation using gravitational redshifts and radii of 137 white dwarfs in wide binaries with main sequence companions. We obtain the space velocities to these systems using the main sequence companion, and subtract these Doppler redshifts from the white dwarfs' apparent motions, isolating their gravitational redshifts. We use Gaia data to calculate the surface temperatures and radii of these white dwarfs, thereby deriving an empirical gravitational redshift-radius relation. This work demonstrates the utility of low-resolution Galactic surveys to measure the white dwarf equation of state. Our results are consistent with theoretical models, and represent the largest sample of individual white dwarf gravitational redshift measurements to date.Comment: 12 pages, 9 figure

A Rhesus Macaque Radiation Hybrid Map and Comparative Analysis with the Human Genome

The genomes of nonhuman primates are powerful references for better understanding the recent evolution of the human genome. Here we compare the order of 802 genomic markers mapped in a rhesus macaque (Macaca mulatta) radiation hybrid panel with the human genome, allowing for nearly complete cross-reference to the human genome at an average resolution of 3.5 Mb. At least 23 large-scale chromosomal rearrangements, mostly inversions, are needed to explain the changes in marker order between human and macaque. Analysis of the breakpoints flanking inverted chromosomal segments and estimation of their duplication divergence dates provide additional evidence implicating segmental duplications as a major mechanism of chromosomal rearrangement in recent primate evolution

Measuring the Mass–Radius Relation of White Dwarfs Using Wide Binaries

Measuring the mass–radius relation of individual white dwarfs is an empirically challenging task that has been performed for only a few dozen stars. We measure the white dwarf mass–radius relation using the gravitational redshifts and radii of 135 white dwarfs in wide binaries with main-sequence companions. We obtain the radial velocities of these systems using the main-sequence companion, and subtract these Doppler redshifts from the white dwarfs’ apparent motions, isolating their gravitational redshifts. We use Gaia data to calculate the surface temperatures and radii of these white dwarfs, thereby deriving an empirical gravitational redshift–radius relation. This work demonstrates the utility of low-resolution Galactic surveys to measure the white dwarf equation of state. Our results are consistent with theoretical models, and represent the largest sample of individual white dwarf gravitational redshift measurements to date

Reconstructing the Sedimentology and Depositional Setting of the Margin Unit, Jezero Crater

International audienceThe Margin Unit of Jezero crater is an olivine- and carbonate-rich geologic unit stratigraphically underlying the Jezero Western fan, tracing the inner margin of the western crater rim, and is of significant astrobiological interest [1]. However, the origin of the Margin Unit is uncertain. The distribution of the unit around the inner margin of the crater rim and its strong orbital carbonate signature led to one interpretation of the Margin Unit as a lake shore precipitate [1] either coeval with, or predating, the Western fan [2]. Alternate hypotheses include fluviolacustrine or aeolian [3], or part of a regional carbonatized lava flow or pyroclastic deposit [4-6]. Here, we report on Perseverance rover observations of the sedimentology and 3D architecture of the Margin Unit explored between sols 910 – 1028, with the objective of characterizing the unit and understanding its emplacement/depositional processes

Reconstructing the Sedimentology and Depositional Setting of the Margin Unit, Jezero Crater

International audienceThe Margin Unit of Jezero crater is an olivine- and carbonate-rich geologic unit stratigraphically underlying the Jezero Western fan, tracing the inner margin of the western crater rim, and is of significant astrobiological interest [1]. However, the origin of the Margin Unit is uncertain. The distribution of the unit around the inner margin of the crater rim and its strong orbital carbonate signature led to one interpretation of the Margin Unit as a lake shore precipitate [1] either coeval with, or predating, the Western fan [2]. Alternate hypotheses include fluviolacustrine or aeolian [3], or part of a regional carbonatized lava flow or pyroclastic deposit [4-6]. Here, we report on Perseverance rover observations of the sedimentology and 3D architecture of the Margin Unit explored between sols 910 – 1028, with the objective of characterizing the unit and understanding its emplacement/depositional processes