Ultra-hot giant exoplanets receive thousands of times Earth’s insolation 1 , 2 . Their high-temperature atmospheres (>2,000 K) are ideal laboratories for studying extreme planetary climates and chemistry 3 – 5 . Daysides are predicted to be cloud-free, dominated by atomic species 6 and substantially hotter than nightsides 5 , 7 , 8 . Atoms are expected to recombine into molecules over the nightside 9 , resulting in different day-night chemistry. While metallic elements and a large temperature contrast have been observed 10 – 14 , no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night (“evening”) and night-to-day (“morning”) terminators could, however, be revealed as an asymmetric absorption signature during transit 4 , 7 , 15 . Here, we report the detection of an asymmetric atmospheric signature in the ultra-hot exoplanet WASP-76b. We spectrally and temporally resolve this signature thanks to the combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by −11±0.7 km s -1 on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside 16 . In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. Iron must thus condense during its journey across the nightside.

We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a sample of 22 BL Lac objects detected (or candidates) at TeV energies, aimed to determine or constrain their redshift. This is of fundamental importance for the interpretation of their emission models, for population studies and also mandatory to study the interaction of high energy photons with the extragalactic background light using TeV sources. High signal-to-noise optical spectra in the range 4250 -10000Å were obtained to search for faint emission and/or absorption lines from both the host galaxy or the nucleus. We determine a new redshift for PKS 1424+240 (z = 0.604) and a tentative one for 1ES 0033+595 (z = 0.467). We are able to set new spectroscopic redshift lower limits for other three sources on the basis of Mg II and Ca II intervening absorption features: BZB J1243+3627 (z > 0.483), BZB J1540+8155 (z > 0.672), and BZB 0J2323+4210 (z > 0.267). We confirm previous redshift estimates for four blazars: S3 0218+357 (z = 0.944), 1ES 1215+303 (z = 0.129), W Comae (z = 0.102), and MS 1221.8+2452 (z = 0.218). For the remaining targets, in seven cases (S2 0109+22, 3C 66A, VER J0521+211, S4 0954+65, BZB J1120+4214, S3 1227+25, BZB J2323+4210), we do not validate the proposed redshift. Finally for all sources of still unknown redshift, we set a lower limit based on the minimum equivalent width of absorption features expected from the host galaxy.

We present a catalog of radio-loud candidate γ-ray emitting blazars with WISE mid-infrared colors similar to the colors of confirmed γ-ray blazars. The catalog is assembled from WISE sources detected in all four WISE filters, with colors compatible with the three-dimensional locus of the WISE γ-ray emitting blazars, and which can be spatially cross-matched with radio sources from either one of the three radio surveys: NVSS, FIRST and/or SUMSS. Our initial WISE selection uses a slightly modified version of previously successful algorithms. We then select only the radio-loud sources using a measure of the radio-to-IR flux, the q 22 parameter, which is analogous to the q 24 parameter known in the literature but which instead uses the WISE band-four flux at 22 µm. Our final catalog contains 7855 sources classified as BL Lacs, FSRQs or mixed candidate blazars; 1295 of these sources can be spatially re-associated with confirmed blazars. We describe the properties of the final catalog of WISE blazar-like radio-loud sources and consider possible contaminants. Finally, we discuss why this large catalog of candidate γ-ray emitting blazars represents a new and useful resource to address the problem of finding low energy counterparts to currently unidentified high-energy sources.

The dissipation of energy flux in blazar jets plays a key role in the acceleration of relativistic particles. Two possibilities are commonly considered for the dissipation processes, magnetic reconnection -possibly triggered by instabilities in magnetically-dominated jets -, or shocks -for weakly magnetized flows. We consider the polarimetric features expected for the two scenarios analyzing the results of state-of-the-art simulations. For the magnetic reconnection scenario we conclude, using results from global relativistic MHD simulations, that the emission likely occurs in turbulent regions with unstructured magnetic fields, although the simulations do not allow us to draw firm conclusions. On the other hand, with local particle-in-cell simulations we show that, for shocks with a magnetic field geometry suitable for particle acceleration, the self-generated magnetic field at the shock front is predominantly orthogonal to the shock normal and becomes quasi-parallel downstream. Based on this result we develop a simplified model to calculate the frequency-dependent degree of polarization, assuming that high-energy particles are injected at the shock and cool downstream. We apply our results to HBLs, blazars with the maximum of their synchrotron output at UV-soft X-ray energies. While in the optical band the predicted degree of polarization is low, in the X-ray emission it can ideally reach 50%, especially during active/flaring states. The comparison between measurements in the optical and in the X-ray band made during active states (feasible with the planned IXPE satellite) are expected to provide valuable constraints on the dissipation and acceleration processes.

A significant fraction (∼ 30%) of the gamma-ray sources listed in the second Fermi LAT (2FGL) catalog is still of unknown origin, being not yet associated with counterparts at lower energies. Using the available information at lower energies and optical spectroscopy on the selected counterparts of these gamma-ray objects we can pinpoint their exact nature. Here we present a pilot project pointing to assess the effectiveness of the several classification methods developed to select gamma-ray blazar candidates.To this end, we report optical spectroscopic observations of a sample of 5 gamma-ray blazar candidates selected on the basis of their infrared WISE colors or of their lowfrequency radio properties. Blazars come in two main classes: BL Lacs and FSRQs, showing similar optical spectra except for the stronger emission lines of the latter.For three of our sources the almost featureless optical spectra obtained confirm their BL Lac nature, while for the source WISEJ022051.24+250927.6 we observe emission lines with equivalent width EW ∼ 31 Å, identifying it as a FSRQ with z = 0.48. The source WISEJ064459.38+603131.7, although not featuring a clear radio counterpart, shows a blazar-like spectrum with weak emission lines with EW ∼ 7 Å, yielding a redshift estimate of z = 0.36. In addition we report optical spectroscopic observations of 4 WISE sources associated with known gamma-ray blazars without a firm classification or redshift estimate. For all of these latter sources we confirm a BL Lac classification, with a tentative redshift estimate for the source WISEJ100800.81+062121.2 of z = 0.65.

The extragalactic γ-ray sky is dominated by the emission arising from blazars, one of the most peculiar classes of radio-loud active galaxies. Since the launch of Fermi several methods were developed to search for blazars as potential counterparts of unidentified γ-ray sources (UGSs). To confirm the nature of the selected candidates, optical spectroscopic observations are necessary. In 2013 we started a spectroscopic campaign to investigate γ-ray blazar candidates selected according to different procedures. The main goals of our campaign are: (1) to confirm the nature of these candidates, and (2) whenever possible, determine their redshifts. Optical spectroscopic observations will also permit us to verify the robustness of the proposed associations and check for the presence of possible source class contaminants to our counterpart selection. This paper reports the results of observations carried out in 2014 in the northern hemisphere with Kitt Peak National Observatory and in the southern hemisphere with the Southern Astrophysical Research telescopes. We also report three sources observed with the Magellan and Palomar telescopes. Our selection of blazar-like sources that could be potential counterparts of UGSs is based on their peculiar infrared colors and on their combination with radio observations both at high and low frequencies (i.e., above and below ∼1 GHz) in publicly available large radio surveys. We present the optical spectra of 27 objects. We confirm the blazar-like nature of nine sources that appear to be potential low-energy counterparts of UGSs. Then we present new spectroscopic observations of 10 active galaxies of uncertain type associated with Fermi sources, classifying all of them as blazars. In addition, we present the spectra for five known γ-ray blazars with uncertain redshift estimates and three BL Lac candidates that were observed during our campaign. We also report the case for WISE J173052.85−035247.2, candidate counterpart of the source 2FGL J1730.6−0353, which has no radio counterpart in the major radio surveys. We confirm that our selection of γ-ray blazars candidates can successfully indentify low-energy counterparts to Fermi unassociated sources and allow us to discover new blazars.

Sharpley et al., 1994). These lpa mutants produced seeds in which the chemistry of seed P, but not the total Phytic acid is a nearly ubiquitous component of plant seeds, supplyamount of P, was greatly altered (Raboy and Gerbasi, ing both phosphate (P) and cations during germination. However, during digestion, the phytic acid form of P is not bioavailable for

We present two catalogs of radio-loud candidate blazars whose WISE mid-infrared colors are selected to be consistent with the colors of confirmed γ-ray emitting blazars. The first catalog is the improved and expanded release of the WIBRaLS catalog presented by D' Abrusco et al. (2014): it includes sources detected in all four WISE filters, spatially cross-matched with radio source in one of three radio surveys and radio-loud based on their q 22 spectral parameter. WIBRaLS2 includes 9541 sources classified as BL Lacs, FSRQs or mixed candidates based on their WISE colors. The second catalog, called KDEBLLACS, based on a new selection technique, contains 5579 candidate BL Lacs extracted from the population of WISE sources detected in the first three WISE passbands ([3.4], [4.6] and [12]) only, whose mid-infrared colors are similar to those of confirmed, γ-ray BL Lacs. KDBLLACS members area also required to have a radio counterpart and be radio-loud based on the parameter q 12 , defined similarly to q 22 used for the WIBRaLS2. We describe the properties of these catalogs and compare them with the largest samples of confirmed and candidate blazars in the literature. We crossmatch the two new catalogs with the most recent catalogs of γ-ray sources detected by Fermi LAT instrument. Since spectroscopic observations of candidate blazars from the first WIBRaLS catalog within the uncertainty regions of γ-ray unassociated sources confirmed that ∼ 90% of these candidates are blazars, we anticipate that these new catalogs will play again an important role in the identification of the γ-ray sky.