Classification of Fermi-LAT unidentified gamma-ray sources using CatBoost gradient boosting decision trees

The latest $\textit{Fermi}$-LAT gamma-ray catalog, 4FGL-DR3, presents a large fraction of sources without clear association to known counterparts, i.e., unidentified sources (unIDs). In this paper, we aim to classify them using machine learning algorithms, which are trained with the spectral characteristics of associated sources to predict the class of the unID population. With the state-of-the-art $\texttt{CatBoost}$ algorithm, based on gradient boosting decision trees, we are able to reach a 67% accuracy on a 23-class dataset. Removing a single of these classes -- blazars of uncertain type -- increases the accuracy to 81%. If interested only in a binary AGN/pulsar distinction, the model accuracy is boosted up to 99%. Additionally, we perform an unsupervised search among both known and unID population, and try to predict the number of clusters of similar sources, without prior knowledge of their classes. The full code used to perform all calculations is provided as an interactive Python notebook.Comment: 8 pages, 8 figures. Matches the accepted MNRAS versio

Redshift prediction of Fermi-LAT gamma-ray sources using CatBoost gradient boosting decision trees

The determination of distance is fundamental in astrophysics. Gamma-ray sources are poorly characterized in this sense, as the limited angular resolution and poor photon-count statistics in gamma-ray astronomy makes it difficult to associate them to a multiwavelength object with known redshift. Taking the 1794 active galactic nuclei (AGNs) with known redshift from the Fermi-LAT latest AGN catalog, 4LAC-DR3, we employ machine learning techniques to predict the distance of the rest of AGNs based on their spectral and spatial properties. The state-of-the-art CatBoost algorithm reaches an average 0.56 R2 score with 0.46 root-mean-squared error (RMSE), predicting an average redshift value of $z_{avg}=0.63$, with a maximum $z_{max}=1.97$. We use the SHAP explainer package to gain insights into the variables influence on the outcome, and also study the extragalactic bakground light (EBL) implications. In a second part, we use this regression model to predict the redshift of the unassociated sample of the latest LAT point-source catalog, 4FGL-DR3, using the results of a previous paper to determine the possible AGNs within them.Comment: 7 pages, 7 figures. Matches the accepted MNRAS versio

Multimarket Contact in Pharmaceutical Markets

The purpose of this paper is to analyze the effect of multimarket contact on the behavior of pharmaceutical firms controlling for different levels of regulatory constraints using IMS MIDAS database. Theoretically, firms that meet in several markets are expected to be capable of sustaining implicitly more profitable out- comes, even if perfect monitoring is not possible. Firms may find it profitable to redistribute their market power among markets where they are operating. We present evidence for nine OECD countries with different degrees of regulation and show that regulation affects the importance of economic forces on firms' price setting behavior. Furthermore, our results confirms the presence of the predictions of the multimarket theory for more market friendly countries (U.S. and Canada) and less regulated ones (U.K., Germany, Netherlands), in contrast, for highly regulated countries (Japan, France, Italy and Spain) the results are less clear with some countries beingPharmaceutical prices, Multimarket Contact, Regulation

Multimarket contact in pharmaceutical markets

We analyze the effect of multimarket contact on the pricing behavior of pharmaceutical firms controlling for different levels of regulatory constraints using the IMS MIDAS database for the industry. Theoretically, under product differentiation, firms may find it profitable to allocate their market power among markets where they are operating, specifically from more collusive to more competitive ones. We present evidence for nine OECD countries suggesting the existence of a multimarket effect for more market friendly countries (U.S. and Canada) and less regulated ones (U.K., Germany, Netherlands), while the results are more unstable for highly regulated countries with some countries being consistent with the theory (France) while others contradicting it (Japan, Italy and Spain). A key result indicates that in the latter countries, price constraints are so intense, that there is little room for allocating market power. Thus equilibrium prices are expected in general to be lower in regulated countries.Pharmaceutical prices, Multimarket Contact, Regulation

Acerca de una defectuosa educación matemática

El objetivo de este artículo es analizar algunos de los defectos más habituales que, a nuestro juicio, se producen en la enseñanza de las matemáticas, a la ver que hacer una reflexión sobre el grado de formación matemática de la sociedad española

Matemáticos españoles en los umbrales del siglo XX: La historia de nuestro despertar matemático

El papel que la matemática española ha jugado en el panorama internacional ha sido siempre exiguo, salvo en la etapa de la dominación árabe (probablemente fuéramos entonces el foco científico más importante del mundo) y en estas últimas décadas (actualmente se encuentra en torno al décimo puesto en la producción matemática mundial). En particular, a finales del siglo XVIII nuestro estado matemático es lamentable, pero a lo largo del XIX la situación va progresando. Esta mejora se percibe especialmente en su último tercio y, más aún, a raíz de la crisis del 98 y durante las primeras décadas del siglo XX. En las páginas siguientes estudiaremos quiénes fueron los matemáticos españoles más importantes de finales del XIX y principios del XX, y cómo fue esa evolución a la que nos hemos referido. Pero para ello debemos comenzar un poco ante

Students\u27 perception of performance through self-assessment

This study was designed as a qualitative investigation and it focuses on the non-graded self-assessment adult ESL students make of their performance. It is based upon findings from previous studies of self-assessment in several settings (Glazer, 1999; Glazer et al., 1995; Optiz, 1995; Manning, 1997; Levy, 1999; Fazey, 1993; Boud, 1992; Orsmond et al., 1997; Sullivan and Hall, 1997; and Lan, 1996). The present research reports and analyzes data collected from eleven students who expressed their views concerning their performance through a checklist, two questionnaires and an interview in an ESL setting. The data collected and analyzed suggest that students are very capable of carrying out self-assessment; they are usually more demanding of themselves than their teachers are; and the process of self-assessment may help them realize ways to improve their performance

X-ray and gamma-ray limits on the primordial black hole abundance from Hawking radiation

The non-observation of Hawking radiation from primordial black holes of $10^{16}$g sets a conservative strong bound on their cosmological abundance. We revisit this bound and show how it can be improved (both in mass reach and strength) by an adequate modeling of the combined AGN and blazar emission in the MeV range. We also estimate the sensitivity to the primordial black hole abundance of a future X-ray experiment capable of identifying a significantly larger number of astrophysical sources contributing to the diffuse background in this energy range.Comment: 5 pages, 2 figures. Accepted for publication in Physics Letters

Constraints to dark matter annihilation from high-latitude hawc unidentified sources

The ΛCDM cosmological framework predicts the existence of thousands of subhalos in our own Galaxy not massive enough to retain baryons and become visible. Yet, some of them may outshine in gamma rays provided that the dark matter is made of weakly interacting massive particles (WIMPs), which would self-annihilate and would appear as unidentified gamma-ray sources (unIDs) in gamma-ray catalogs. Indeed, unIDs have proven to be competitive targets for dark matter searches with gamma rays. In this work, we focus on the three high-latitude (|b| ≥ 10) sources present in the 2HWC catalog of the High Altitude Water Cherenkov (HAWC) observatory with no clear associations at other wavelengths. Indeed, only one of these sources, 2HWC J1040+308, is found to be above the HAWC detection threshold when considering 760 days of data, i.e., a factor 1.5 more exposure time than in the original 2HWC catalog. Other gamma-ray instruments, such as Fermi-LAT or VERITAS at lower energies, do not detect the source. Also, this unID is reported as spatially extended, making it even more interesting in a dark matter search context. While waiting for more data that may shed further light on the nature of this source, we set competitive upper limits on the annihilation cross section by comparing this HAWC unID to expectations based on state-of-the-art N-body cosmological simulations of the Galactic subhalo population. We find these constraints to be particularly competitive for heavy WIMPs, i.e., masses above ∼25 (40) TeV in the case of the b ¯b (τ +τ −) annihilation channel, reaching velocity-averaged cross section values of 2 × 10−25 (5 × 10−25) cm3 ·s −1 . Although far from testing the thermal relic cross section value, the obtained limits are independent and nicely complementary to those from radically different DM analyses and targets, demonstrating once again the high potential of this DM search approachJ.C.-B. and M.A.S.-C. are supported by the Atracción de Talento contract no. 2016-T1/TIC-1542 granted by the Comunidad de Madrid in Spain, by the Spanish Agencia Estatal de Investigación through the grants PGC2018-095161-B-I00, IFT Centro de Excelencia Severo Ochoa SEV-2016-0597, and Red Consolider MultiDark FPA2017-90566-RED