Projects
Below are some projects for which we are seeking students or postdoctoral researchers. If you are interested in becoming involved, please contact us.
Title: Identifying Gamma-Ray Blazar Candidates from their IR Colors
Description: Blazars can be identified and categorized from their IR colors. Gamma-ray sources, many of them of unidentified character like those discovered with Fermi, might be blazars and thereby pinpointed for follow-up identification and study. The WISE IR bands (W1-W4) serve as diagnostic tools (see figure). We are currently conducting a large follow-up program focusing on spectroscopic analysis using SOAR, Blanco, NTT, and OAN-SPM telescopes.
Estimated Timeline: 1 year
Required Expertise: General excellence in astronomy and computer skills
Image courtesy: D'Abrusco et al. 2019, ApJS, 242, 4
Title: Understanding the Nature of Sgr A* Variability and Flares using Chandra, SMA, and JWST Observations
Description: This ongoing project involves a large team dedicated to studying the IR-submm variability of SgrA*. In 2024, we obtained new results from the SMA and other missions.
Estimated Timeline: 6-12 months
Required Expertise: General excellence in astronomy and computer skills
Title: Spectral Energy Distribution Modeling of a Sample of ~300 IR Bright Galaxies of Many Types from Optical to Submm
Description: The spectral energy distribution (SED) of a galaxy can be modeled to measure the different physical processes shaping it. These include stellar atmospheres, dust heated by starbursts, star-formation rates, AGN accretion activity, other details such as stellar and dust masses, and evolutionary states such as mergers. We have compiled approximately 35 photometric point SEDs from around 300 nearby infrared galaxies, spanning from near to far-infrared ranges, and used the CIGALE analysis package (see figure). To understand galaxies at z>~2, where many internal processes are too faint for direct measurement, broad SED analyses provide essential tools. However, this is only possible if the SEDs of nearby galaxies are well-understood. This project will continue our analysis using our newly completed reduced dataset to classify the objects, explain trends, and identify outlier objects for further study, with one or more papers to be produced.
Estimated Timeline: 6-12 months
Required Expertise: General excellence in astronomy and computer skills
Image courtesy: Dietrich et al. 2018, MNRAS, 480, 3
Title: Broadband Spectral Energy Distribution of ACT-Selected AGN
Description: Bright radio galaxies are detected in the broadband millimeter survey of the Atacama Cosmology Telescope. Roughly 150 source fluxes have been extracted and identified as AGN, and the positions have been cross-matched with other survey maps, such as the VLA FIRST and Herschel SPIRE. What remains is the full modeling of their spectral energy distributions (SEDs), which enables us to distinguish the non-thermal emission of the jet from the thermal dust emission in the host galaxy.
Estimated Timeline: 6-12 months
Required Expertise: Computational modeling, preferably in Python
Novel Numerical Approach to Particle Acceleration in AGN Jets at kinetic Scales
Description: Particle acceleration in the relativistic jets of Active Galactic Nuclei (AGN) and the mechanism of X-ray emission has been an open question (Khard, 2023) since the joint high-resolution X-ray image of the jet PKS 0637-752 by Chandra and the observation of its radio counterpart (Schwartz et al., 2000). In addition, the high level of X-ray polarization degree recently reported by the Imaging X-ray Polarimetry Explorer (IXPE) for AGN/blazars (e.g., Markarian 501, Liodakis et al., 2022) is consistent with a shock acceleration scenario within the jet and magnetic reconnection is disfavoured. These findings imply that the magnetic field of these systems is coherent over much larger length scales than previously thought. However, for blazars, the scenario of particle acceleration at a shock front implies a certain level of magnetic turbulence in the vicinity of the shock that is not observed (due to the high polarization degree); the interpretation of Chandra and IXPE observations can help solve such a puzzle. Insufficient computational resources have long been limiting the spatial/temporal range of kinetic scale simulations of such systems. In this project, we investigate the kinetic scales of the early-on particle acceleration at the mildly relativistic shocks with of AGN/blazars jets making use of new numerical techniques. This pilot study leads the way to a larger future project that will bridge kinetic with larger (magnetohydrodynamic, MHD) scales simulations to interpret Chandra/IXPE observations.
Estimated Timeline: 3 years
Required Expertise: X-rays (Chandra and IXPE) as well as radio, optical and gamma-rays data analysis & interpretation of relativistic jets in AGN/blazars
Identifying AGN in the Chandra Source Catalog and Their Multiwavelength Cross-Matches
Description: Chandra has significantly advanced our understanding of AGN by identifying tens of thousands throughout most of cosmic history. The Chandra Source Catalog Version 2.1 (CSC2.1), released in 2024, offers a comprehensive characterization of AGN, with an estimated 20,000 AGN included. This project aims to cross-match X-ray selected AGN in CSC2.1 with various sky surveys, including SDSS, GALEX, Gaia, PanSTARRS, 2MASS, WISE, and Radio Catalogs, and compile the multiwavelength SED of the AGN in CSC 2.1.
Estimated Timeline: 6 months
Required Expertise: Proficiency in astronomy and computer skills, particularly in Python
AGN and Host Galaxy Connection in the Chandra Source Catalog
Description: In this project we aim to estimate the fundamental properties of ~20000 AGN in the Chandra Source Catalog Version 2.1 (CSC2.1) and the galaxies nourishing them by applying a novel SED fitting method to the latest CSC AGN sample. This model treats the radio (in the case of radio-loud AGN)/IR to X-ray SED simultaneously and constrains the fundamental properties such as BH masses, spins, Eddington ratios, star-formation rates (SFR), and stellar masses. This project harnesses the tremendous statistical strength of the CSC AGN sample to determine whether AGN properties are related to the SFR or stellar mass of their hosts.
Estimated Timeline: 1 year
Required Expertise: Proficiency in astronomy and computer skills, particularly in Python