Browsing by Author "Bauer, Franz E. "

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    BASS XXXII: Studying the Nuclear Millimeter-wave Continuum Emission of AGNs with ALMA at Scales ≲100-200 pc
    (2022) Kawamuro, Taiki; Ricci, Claudio; Imanishi, Masatoshi; Mushotzky, Richard F.; Izumi, Takuma; Ricci, Federica; Bauer, Franz E.; Koss, Michael J.; Trakhtenbrot, Benny; Ichikawa, Kohei; Rojas, Alejandra F.; Smith, Krista Lynne; Shimizu, Taro; Oh, Kyuseok; den Brok, Jakob S.; Baba, Shunsuke; Balokovic, Mislay; Chang, Chin-Shin; Kakkad, Darshan; Pfeifle, Ryan W.; Privon, George C.; Temple, Matthew J.; Ueda, Yoshihiro; Harrison, Fiona; Powell, Meredith C.; Stern, Daniel; Urry, Meg; Sanders, David B.
    To understand the origin of nuclear (less than or similar to 100 pc) millimeter-wave (mm-wave) continuum emission in active galactic nuclei (AGNs), we systematically analyzed subarcsecond resolution Band-6 (211-275 GHz) Atacama Large Millimeter/submillimeter Array data of 98 nearby AGNs (z < 0.05) from the 70 month Swift/BAT catalog. The sample, almost unbiased for obscured systems, provides the largest number of AGNs to date with high mm-wave spatial resolution sampling (similar to 1-200 pc), and spans broad ranges of 14-150 keV luminosity {40< log [L-14(-150)/(erg s(-1))] < 45}, black hole mass [5 < log(M-BH/M-circle dot) < 10], and Eddington ratio (-4 < log lambda(Edd) < 2). We find a significant correlation between 1.3 mm (230 GHz) and 14-150 keV luminosities. Its scatter is approximate to 0.36 dex, and the mm-wave emission may serve as a good proxy of the AGN luminosity, free of dust extinction up to N-H similar to 10(26) CM-2. While the mm-wave emission could be self-absorbed synchrotron radiation around the X-ray corona according to past works, we also discuss different possible origins of the mm-wave emission: AGN-related dust emission, outflow-driven shocks, and a small-scale (<200 pc) jet. The dust emission is unlikely to be dominant, as the mm-wave slope is generally flatter than expected. Also, due to no increase in the mm-wave luminosity with the Eddington ratio, a radiation-driven outflow model is possibly not the common mechanism Furthermore, we find independence of the mm-wave luminosity on indicators of the inclination angle from the polar axis of the nuclear structure, which is inconsistent with a jet model whose luminosity depends only on the angle.
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    BASS-XL: X-ray variability properties of unobscured active galactic nuclei
    (2023) Tortosa, Alessia; Ricci, Claudio; Arevalo, Patricia; Koss, Michael J.; Bauer, Franz E.; Trakhtenbrot, Benny; Mushotzky, Richard; Temple, Matthew J.; Ricci, Federica; Lilayu, Alejandra Rojas; Kawamuro, Taiki; Caglar, Turgay; Liu, Tingting; Harrison, Fiona; Oh, Kyuseok; Powell, Meredith Clark; Stern, Daniel; Urry, Claudia Megan
    We investigate the X-ray variability properties of Seyfert 1 Galaxies belonging to the BAT AGN Spectroscopic Survey (BASS). The sample includes 151 unobscured (N-H < 10(22) cm(-2)) AGNs observed with XMM-Newton for a total exposure time of similar to 27 ms, representing the deepest variability study done so far with high signal-to-noise XMM-Newton observations, almost doubling the number of observations analysed in previous works. We constrain the relation between the normalized excess variance and the 2-10 keV AGN luminosities, black hole masses, and Eddington ratios. We find a highly significant correlation between sigma(2)(NXS) and M-BH, with a scatter of similar to 0.85 dex. For sources with high L2-10 this correlation has a lower normalization, confirming that more luminous (higher mass) AGNs show less variability. We explored the sigma(2)(NXS) versus M-BH relation for the sub-sample of sources with M-BH estimated via the 'reverberation mapping' technique, finding a tighter anticorrelation, with a scatter of similar to 0.65 dex. We examine how the sigma(2)(NXS) changes with energy by studying the relation between the variability in the hard (3-10 keV) and the soft (0.2-1 keV)/medium (1-3 keV) energy bands, finding that the spectral components dominating the hard energy band are more variable than the spectral components dominating in softer energy bands, on time-scales shorter than 10 ks.
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    BASS. LIII. The Eddington Ratio as the Primary Regulator of the Fraction of X-Ray Emission in Active Galactic Nuclei
    (2025) Gupta, Kriti Kamal; Ricci, Claudio; Tortosa, Alessia; Temple, Matthew J.; Koss, Michael J.; Trakhtenbrot, Benny; Bauer, Franz E.; Treister, Ezequiel; Mushotzky, Richard; Kammoun, Elias; Papadakis, Iossif; Oh, Kyuseok; Rojas, Alejandra; Chang, Chin-Shin; Diaz, Yaherlyn; Jana, Arghajit; Kakkad, Darshan; Moral Castro, Ignacio del; Peca, Alessandro; Powell, Meredith C.; Stern, Daniel; Urry, C. Megan; Harrison, Fiona
    Active galactic nuclei (AGN) emit radiation via accretion across the entire energy spectrum. While the standard disk and corona model can somewhat describe this emission, it fails to predict specific features such as the soft X-ray excess, the short-term optical/UV variability, and the observed UV/X-ray correlation in AGN. In this context, the fraction of AGN emission in different bands (i.e., bolometric corrections) can be useful to better understand the accretion physics of AGN. Past studies have shown that the X-ray bolometric corrections are strongly dependent on the physical properties of AGN, such as their luminosities and Eddington ratios. However, since these two parameters depend on each other, it has been unclear which is the main driver of the X-ray bolometric corrections. We present here results from a large study of hard-X-ray-selected (14–195 keV) nearby (z < 0.1) AGN. Based on our systematic analysis of the simultaneous optical-to-X-ray spectral energy distributions of 236 unobscured AGN, we found that the primary parameter controlling the X-ray bolometric corrections is the Eddington ratio. Our results show that, while the X-ray bolometric correction increases with the bolometric luminosity for sources with intermediate Eddington ratios (0.01–1), this dependence vanishes for sources with lower Eddington ratios (<0.01). This could be used as evidence for a change in the accretion physics of AGN at low Eddington ratios.
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    BASS. XXIX. The Near-infrared View of the Broad-line Region (BLR): The Effects of Obscuration in BLR Characterization
    (2022) Ricci, Federica ; Treister, Ezequiel ; Bauer, Franz E.; Mejía-Restrepo, Julian E. ; Koss, Michael J. ; den Brok, Jakob S. ; Baloković, Mislav ; Bär, Rudolf ; Bessiere, Patricia ; Caglar, Turgay ; Harrison, Fiona ; Ichikawa, Kohei ; Kakkad, Darshan; Lamperti, Isabella ; Mushotzky, Richard ; Oh, Kyuseok ; Powell, Meredith C. ; Privon, George C. ; Ricci, Claudio ; Riffel, Rogerio ; Rojas, Alejandra F. ; Sani, Eleonora ; Smith, Krista L. ; Stern, Daniel ; Trakhtenbrot, Benny ; Urry, C. Megan ; Veilleux, Sylvain
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    BASS. XXVIII. Near-infrared Data Release 2: High-ionization and Broad Lines in Active Galactic Nuclei
    (2022) den Brok, Jakob S.; Koss, Michael J.; Trakhtenbrot, Benny; Stern, Daniel; Cantalupo, Sebastiano; Lamperti, Isabella; Ricci, Federica; Ricci, Claudio; Oh, Kyuseok; Bauer, Franz E.; Riffel, Rogerio; Rodriguez-Ardila, Alberto; Baer, Rudolf; Harrison, Fiona; Ichikawa, Kohei; Mejia-Restrepo, Julian E.; Mushotzky, Richard; Powell, Meredith C.; Boissay-Malaquin, Rozenn; Stalevski, Marko; Treister, Ezequiel; Urry, C. Megan; Veilleux, Sylvain
    We present the BAT AGN Spectroscopic Survey (BASS) Near-infrared Data Release 2 (DR2), a study of 168 nearby ((z) over bar = 0.04, z < 0.6) active galactic nuclei (AGN) from the all-sky Swift Burst Array Telescope X-ray survey observed with the Very Large Telescope (VLT)/X-shooter in the near-infrared (NIR; 0.8-2.4 mu m). We find that 49/109 (45%) Seyfert 2 and 35/58 (60%) Seyfert 1 galaxies observed with VLT/X-shooter show at least one NIR high-ionization coronal line (CL; ionization potential chi > 100 eV). Comparing the emission of the [Si VI] lambda 1.9640 CL with the X-ray emission for the DR2 AGN, we find a significantly tighter correlation, with a lower scatter (0.37 dex) than that for the optical [O III] lambda 5007 line (0.71 dex). We do not find any correlation between CL emission and the X-ray photon index Gamma. We find a clear trend of line blueshifts with increasing ionization potential in several CLs, such as [Si VI] lambda 1.9640, [Si X] lambda 1.4300, [S VIII] lambda 0.9915, and [S IX] lambda 1.2520, indicating the radial structure of the CL region. Finally, we find a strong underestimation bias in black hole mass measurements of Sy 1.9 using broad H alpha due to the presence of significant dust obscuration. In contrast, the broad Pa alpha and Pa beta emission lines are in agreement with the M-sigma relation. Based on the combined DR1 and DR2 X-shooter sample, the NIR BASS sample now comprises 266 AGN with rest-frame NIR spectroscopic observations, the largest set assembled to date.
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    Chandra Observations of Excess Fe Kα Line Emission in Galaxies with High Star Formation Rates: X-Ray Reflection on Galaxy Scales?
    (2021) Yan, Wei; Hickox, Ryan C.; Chen, Chien-Ting J.; Ricci, Claudio; Masini, Alberto; Bauer, Franz E.; Alexander, David M.
    In active galactic nuclei (AGNs), fluorescent Fe K alpha (iron) line emission is generally interpreted as originating from obscuring material around a supermassive black hole on the scale of a few parsecs. However, recent Chandra studies indicate the existence of iron line emission extending to kiloparsec scales in the host galaxy. The connection between iron line emission and large-scale material can be spatially resolved directly only in nearby galaxies, but could be inferred in more distant AGNs by a connection between line emission and star-forming gas and dust that is more extended than the parsec-scale torus. Here we present the results from a stacking analysis and X-ray spectral fitting performed on sources in the Chandra Deep Field South (CDFS) 7 Ms observations. From the deep stacked spectra, we select sources with stellar mass log(M-*/M-circle dot) > 10 at 0.5 < z < 2, obtaining 25 sources with high-infrared (IR) luminosity (star formation rate, SFRFIR >= 17 M-circle dot yr(-1)) and 32 sources below this threshold. We find that the equivalent width (EW) of the iron line EW(Fe) is a factor of three higher with 3 sigma significance for high-IR luminosity measured from Herschel observations, indicating a connection between iron line emission and star-forming material on galaxy scales. We show that there is no significant dependence of the EW(Fe) on M-* or X-ray luminosity, suggesting that the reflection of AGN X-ray emission over large scales in their host galaxies may be widespread.
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    Deep Learning Identification of Galaxy Hosts in Transients (DELIGHT)
    (2022) Forster, Francisco; Muñoz Arancibia, Alejandra M.; Reyes, Ignacio; Gagliano, Alexander; Britt, Dylan J.; Cuellar-Carrillo, Sara; Figueroa-Tapia, Felipe; Polzin, Ava; Yousef, Yara; Arredondo, Javier; Rodríguez-Mancini, Diego; Correa-Orellana, Javier; Bayo, Amelia; Bauer, Franz E.; Catelan, Márcio; Cabrera-Vives, Guillermo; Dastidar, Raya; Estévez, Pablo A.; Pignata, Giuliano; Hernández-Garcia, Lorena; Huijse, Pablo; Reyes, Esteban; Sánchez-Sáez, Paula; Ramírez, Mauricio; Grandón, Daniela; Pineda-García, Jonathan; Chabour-Barra, Francisca; Silva-Farfán, Javier
    The Deep Learning Identification of Galaxy Hosts in Transients (DELIGHT, Förster et al. 2022, submitted) is a library created by the ALeRCE broker to automatically identify host galaxies of transient candidates using multi-resolution images and a convolutional neural network (you can test it with our example notebook, that you can run in Colab). The initial idea for DELIGHT started as a project proposed for the La Serena School of Data Science in 2021. You can install it using pip install astro-delight, but we recommend cloning this repository and pip install . from there. The library has a class with several methods that allow you to get the most likely host coordinates starting from given transient coordinates. In order to do this, the delight object needs a list of object identifiers and coordinates (oid, ra, dec). With this information, it downloads PanSTARRS images centered around the position of the transients (2 arcmin x 2 arcmin), gets their WCS solutions, creates the multi-resolution images, does some extra preprocessing of the data, and finally predicts the position of the hosts using a multi-resolution image and a convolutional neural network. It can also estimate the host's semi-major axis if requested taking advantage of the multi-resolution images. Note that DELIGHT's prediction time is currently dominated by the time to download PanSTARRS images using the panstamps service. In the future, we expect that there will be services that directly provide multi-resolution images, which should be more lightweight with no significant loss of information. Once these images are obtained, the processing times are only milliseconds per host. If you cannot install some of the dependencies, e.g. tensorflow, you can try running DELIGHT directly from Google Colab (test in this link). Github link: https://github.com/fforster/delight PyPi link: https://pypi.org/project/astro-delight/...
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    DELIGHT: Deep Learning Identification of Galaxy Hosts of Transients using Multiresolution Images
    (2022) Förster, Francisco; Muñoz Arancibia, Alejandra M.; Reyes-Jainaga, Ignacio; Gagliano, Alexander; Britt, Dylan; Cuellar-Carrillo, Sara; Figueroa-Tapia, Felipe; Polzin, Ava; Yousef, Yara; Arredondo, Javier; Rodríguez-Mancini, Diego; Correa-Orellana, Javier; Bayo, Amelia; Bauer, Franz E.; Catelan, Márcio; Cabrera-Vives, Guillermo; Dastidar, Raya; Estévez, Pablo A.; Pignata, Giuliano; Hernández-García, Lorena; Huijse, Pablo; Reyes, Esteban; Sánchez-Sáez, Paula; Ramírez, Mauricio; Grandón, Daniela; Pineda-García, Jonathan; Chabour-Barra, Francisca; Silva-Farfán, Javier
    We present DELIGHT, or Deep Learning Identification of Galaxy Hosts of Transients, a new algorithm designed to automatically and in real time identify the host galaxies of extragalactic transients. The proposed algorithm receives as input compact, multiresolution images centered at the position of a transient candidate and outputs two-dimensional offset vectors that connect the transient with the center of its predicted host. The multiresolution input consists of a set of images with the same number of pixels, but with progressively larger pixel sizes and fields of view. A sample of 16,791 galaxies visually identified by the Automatic Learning for the Rapid Classification of Events broker team was used to train a convolutional neural network regression model. We show that this method is able to correctly identify both relatively large (10″ < r < 60″) and small (r ≤ 10″) apparent size host galaxies using much less information (32 kB) than with a large, single-resolution image (920 kB). The proposed method has fewer catastrophic errors in recovering the position and is more complete and has less contamination (<0.86%) recovering the crossmatched redshift than other state-of-the-art methods. The more efficient representation provided by multiresolution input images could allow for the identification of transient host galaxies in real time, if adopted in alert streams from new generation of large -etendue telescopes such as the Vera C. Rubin Observatory....
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    HARD X-RAY MORPHOLOGICAL AND SPECTRAL STUDIES OF THE GALACTIC CENTER MOLECULAR CLOUD SGR B2: CONSTRAINING PAST SGR A☆ FLARING ACTIVITY
    (2015) Zhang, Shuo; Hailey, Charles J.; Mori, Kaya; Clavel, Maica; Terrier, Regis; Ponti, Gabriele; Goldwurm, Andrea; Bauer, Franz E.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Harrison, Fiona A.; Hong, Jaesub; Nynka, Melania; Soldi, Simona; Stern, Daniel; Tomsick, John A.; Zhang, William W.
    In 2013, NuSTAR observed the Sgr B2 region and for the first time resolved its hard X-ray emission on subarcminute scales. Two prominent features are detected above 10 keV:. a newly emerging cloud, G0.66-0.13, and the central 90 '' radius region containing two compact cores, Sgr B2(M) and Sgr B2(N), surrounded by diffuse emission. It is inconclusive whether the remaining level of Sgr. B2 emission is still decreasing or has reached a constant background level. A decreasing X-ray emission can be best explained by the X-ray reflection nebula scenario, where the cloud reprocesses a past giant outburst from Sgr A(star). In the X-ray reflection nebula (XRN) scenario, the 3-79 keV Sgr. B2 spectrum allows us to self-consistently test the XRN model using both the Fe K alpha line and the continuum emission. The peak luminosity of the past Sgr A(star) outburst is constrained to L3-79keV similar to 5 x 10(38) ergs s(-1). A newly discovered cloud feature, G0.66-0.13, shows different timing variability. We suggest that it could be a molecular clump located in the Sgr B2 envelope reflecting the same Sgr A(star) outburst. In contrast, if the Sgr. B2 X-ray emission has reached a constant background level, it would imply an origin of low-energy cosmic-ray (CR) proton bombardment. In this scenario, from the NuSTAR measurements we infer a CR ion power of dW/dt = (1 - 4) x 10(39) erg s(-1) and a CR ionization rate of zeta(H) = (6 - 10) x 10(-15) H-1 s(-1). measurements can become powerful tools to constrain the GC CR population.
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    The Identification of a Dusty Multiarm Spiral Galaxy at z =3.06 with JWST and ALMA
    (2023) Wu, Yunjing; Cai, Zheng; Sun, Fengwu; Bian, Fuyan; Lin, Xiaojing; Li, Zihao; Li, Mingyu; Bauer, Franz E.; Egami, Eiichi; Fan, Xiaohui; Gonzalez-Lopez, Jorge; Li, Jianan; Wang, Feige; Yang, Jinyi; Zhang, Shiwu; Zou, Siwei
    Spiral arms serve crucial purposes in star formation and galaxy evolution. In this paper, we report the identification of "A2744-DSG-z3," a dusty, multiarm spiral galaxy at z = 3.059 using the James Webb Space Telescope (JWST) NIRISS imaging and grism spectroscopy. A2744-DSG-z3 was discovered as a gravitationally lensed submillimeter galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA). This is the most distant stellar spiral structure seen thus far, consistent with cosmological simulations that suggest z approximate to 3 as the epoch when spirals emerge. Thanks to the gravitational lensing and excellent spatial resolution of JWST, the spiral arms are resolved with a spatial resolution of approximate to 290 pc. Based on spectral energy distribution fitting, the spiral galaxy has a delensed star formation rate of 85 +/- 30 M (circle dot) yr(-1), and a stellar mass of approximate to 10(10.6) M (circle dot), indicating that A2744-DSG-z3 is a main-sequence galaxy. After fitting the spiral arms, we find a stellar effective radius (R (e,star)) of 5.0 +/- 1.5 kpc. Combining with ALMA measurements, we find that the effective radii ratio between dust and stars is approximate to 0.4, similar to those of massive star-forming galaxies (SFGs) at z similar to 2, indicating a compact dusty core in A2744-DSG-z3. Moreover, this galaxy appears to be living in a group environment: including A2744-DSG-z3, at least three galaxies at z = 3.05-3.06 are spectroscopically confirmed by JWST/NIRISS and ALMA, residing within a lensing-corrected projected scale of approximate to 70 kpc. This, along with the asymmetric brightness profile, further suggests that the spiral arms may be triggered by minor-merger events at z greater than or similar to 3.