TY - JOUR AB - We perform a diagrammatic analysis of the energy of a mobile impurity immersed in a strongly interacting two-component Fermi gas to second order in the impurity-bath interaction. These corrections demonstrate divergent behavior in the limit of large impurity momentum. We show the fundamental processes responsible for these logarithmically divergent terms. We study the problem in the general case without any assumptions regarding the fermion-fermion interactions in the bath. We show that the divergent term can be summed up to all orders in the Fermi-Fermi interaction and that the resulting expression is equivalent to the one obtained in the few-body calculation. Finally, we provide a perturbative calculation to the second order in the Fermi-Fermi interaction, and we show the diagrams responsible for these terms. AU - Al Hyder, Ragheed AU - Chevy, F. AU - Leyronas, X. ID - 15167 IS - 3 JF - Physical Review A SN - 2469-9926 TI - Exploring beyond-mean-field logarithmic divergences in Fermi-polaron energy VL - 109 ER - TY - JOUR AB - For some k∈Z≥0∪{∞}, we call a linear forest k-bounded if each of its components has at most k edges. We will say a (k,ℓ)-bounded linear forest decomposition of a graph G is a partition of E(G) into the edge sets of two linear forests Fk,Fℓ where Fk is k-bounded and Fℓ is ℓ-bounded. We show that the problem of deciding whether a given graph has such a decomposition is NP-complete if both k and ℓ are at least 2, NP-complete if k≥9 and ℓ=1, and is in P for (k,ℓ)=(2,1). Before this, the only known NP-complete cases were the (2,2) and (3,3) cases. Our hardness result answers a question of Bermond et al. from 1984. We also show that planar graphs of girth at least nine decompose into a linear forest and a matching, which in particular is stronger than 3-edge-colouring such graphs. AU - Campbell, Rutger AU - Hörsch, Florian AU - Moore, Benjamin ID - 15163 IS - 6 JF - Discrete Mathematics SN - 0012-365X TI - Decompositions into two linear forests of bounded lengths VL - 347 ER - TY - JOUR AB - Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad Hα emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 Hα lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s−1, contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼107–8M⊙. In the UV luminosity range MUV,AGN+host = −21 to −18, we measure number densities of ≈10−5 cMpc−3. This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad Hα LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex Hα profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization. AU - Matthee, Jorryt J AU - Naidu, Rohan P. AU - Brammer, Gabriel AU - Chisholm, John AU - Eilers, Anna-Christina AU - Goulding, Andy AU - Greene, Jenny AU - Kashino, Daichi AU - Labbe, Ivo AU - Lilly, Simon J. AU - Mackenzie, Ruari AU - Oesch, Pascal A. AU - Weibel, Andrea AU - Wuyts, Stijn AU - Xiao, Mengyuan AU - Bordoloi, Rongmon AU - Bouwens, Rychard AU - van Dokkum, Pieter AU - Illingworth, Garth AU - Kramarenko, Ivan AU - Maseda, Michael V. AU - Mason, Charlotte AU - Meyer, Romain A. AU - Nelson, Erica J. AU - Reddy, Naveen A. AU - Shivaei, Irene AU - Simcoe, Robert A. AU - Yue, Minghao ID - 15180 IS - 2 JF - The Astrophysical Journal KW - Space and Planetary Science KW - Astronomy and Astrophysics SN - 0004-637X TI - Little Red Dots: An abundant population of faint active galactic nuclei at z ∼ 5 revealed by the EIGER and FRESCO JWST surveys VL - 963 ER - TY - JOUR AB - The fungal bioluminescence pathway can be reconstituted in other organisms allowing luminescence imaging without exogenously supplied substrate. The pathway starts from hispidin biosynthesis—a step catalyzed by a large fungal polyketide synthase that requires a posttranslational modification for activity. Here, we report identification of alternative compact hispidin synthases encoded by a phylogenetically diverse group of plants. A hybrid bioluminescence pathway that combines plant and fungal genes is more compact, not dependent on availability of machinery for posttranslational modifications, and confers autonomous bioluminescence in yeast, mammalian, and plant hosts. The compact size of plant hispidin synthases enables additional modes of delivery of autoluminescence, such as delivery with viral vectors. AU - Palkina, Kseniia A. AU - Karataeva, Tatiana A. AU - Perfilov, Maxim M. AU - Fakhranurova, Liliia I. AU - Markina, Nadezhda M. AU - Gonzalez Somermeyer, Louisa AU - Garcia-Perez, Elena AU - Vazquez-Vilar, Marta AU - Rodriguez-Rodriguez, Marta AU - Vazquez-Vilriales, Victor AU - Shakhova, Ekaterina S. AU - Mitiouchkina, Tatiana AU - Belozerova, Olga A. AU - Kovalchuk, Sergey I. AU - Alekberova, Anna AU - Malyshevskaia, Alena K. AU - Bugaeva, Evgenia N. AU - Guglya, Elena B. AU - Balakireva, Anastasia AU - Sytov, Nikita AU - Bezlikhotnova, Anastasia AU - Boldyreva, Daria I. AU - Babenko, Vladislav V. AU - Kondrashov, Fyodor AU - Choob, Vladimir V. AU - Orzaez, Diego AU - Yampolsky, Ilia V. AU - Mishin, Alexander S. AU - Sarkisyan, Karen S. ID - 15179 IS - 10 JF - Science Advances SN - 2375-2548 TI - A hybrid pathway for self-sustained luminescence VL - 10 ER - TY - JOUR AB - The elimination of rain evaporation in the planetary boundary layer (PBL) has been found to lead to convective self‐aggregation (CSA) even without radiative feedback, but the precise mechanisms underlying this phenomenon remain unclear. We conducted cloud‐resolving simulations with two domain sizes and progressively reduced rain evaporation in the PBL. Surprisingly, CSA only occurred when rain evaporation was almost completely removed. The additional convective heating resulting from the reduction of evaporative cooling in the moist patch was found to be the trigger, thereafter a dry subsidence intrusion into the PBL in the dry patch takes over and sets CSA in motion. Temperature and moisture anomalies oppose each other in their buoyancy effects, hence explaining the need for almost total rain evaporation removal. We also found radiative cooling and not cold pools to be the leading cause for the comparative ease of CSA to take place in the larger domain. AU - Hwong, Yi-Ling AU - Muller, Caroline J ID - 15186 IS - 6 JF - Geophysical Research Letters KW - General Earth and Planetary Sciences KW - Geophysics SN - 0094-8276 TI - The unreasonable efficiency of total rain evaporation removal in triggering convective self‐aggregation VL - 51 ER -