adsabs/AstroCLIMB huggingface dataset:
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Broadband SED acquired around δ t ≈ 3.4 yr post-merger, including CXO X-ray data (filled circle), VLA upper limits at 3 and 15 GHz (filled squares), MeerKAT flux limit (filled diamond), and HST/F140W flux limit (filled hexagon). The gray open square shows the 3 GHz peak flux pixel value of 2.8 μJy (with rms of 1.3 μJy) within one synthesized beam at the location of GW 170817 from Balasubramanian et al. (2021). The red dotted line shows the F  ν  ∝ ν −(p−1)/2 spectrum with p = 2.166 that best fitted the jet-afterglow data (Fong et al. 2019). The VLA 3 GHz limit suggests a shallower spectrum (Section 5). The orange dashed line shows F  ν  ∝ ν −(p−1)/2 with p = 2.05. HST observations imply an NIR-to-X-ray spectral slope steeper than ≈1.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Probability of simple power-law F  ν  = Norm × ν −(p−1)/2 spectral models at 1234 days that do not violate the three-times rms (orange), and two-times rms (brown) flux density of our 3 GHz image at the location of GW 170817 as a function of p, where rms = 1.7 μ Jy is inferred from this work. The red line and open symbols show the results for rms = 1.3 μ Jy inferred by Balasubramanian et al. (2021). Norm is drawn from the posterior probability distribution of the 0.3–10 keV unabsorbed X-ray flux at 1234 days as derived from MCMC sampling within Xspec. The horizontal gray dashed lines mark the 0.3%, 4.5%, and 50% probability levels. The vertical blue thick and dotted lines show the best-fitting p parameter and 1σ range, respectively, for the jet afterglow as derived from broadband SED fitting of the nonthermal emission of GW 170817 at δ t < 900 days (Fong et al. 2019). This analysis suggests a hardening of the nonthermal spectrum of GW 170817 at 1234 days to values of p less than the best-fitting value from the earlier jet afterglow at statistical confidence ≥92%–99.2%.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: The blue shaded area shows the region of the parameter space consistent with the X-ray flux excess at 1234 days following the modeling described in Section 7. The orange shaded area shows the region of the parameter space that is consistent with our radio upper limit at 3 GHz: F  ν  < 5.1 μJy. The kinetic energy distribution of the kilonova ejecta in the velocity space has been parameterized as E KN ∝ (Γβ)−α  above β 0 with E KN(Γ0 β 0) = 1051 erg. The shock microphysical parameters adopted in this calculation are p = 2.05 (consistent with the observational findings of Section 5) and ϵ  e  = 0.1. Two parameters are varied in each plot while the rest are kept fixed to values indicated in the plot title.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Kilonova afterglow parameter space with the same color scheme as Figure 7 where we used the peak pixel flux within one synthesized beam at 3 GHz from Balasubramanian et al. (2021; F  ν  = 2.8 ± 1.3 μJy) as a constraint on the radio emission from the kilonova. As in Figure 7, we assume E KN = 1051 erg, ϵ  e  = 0.1, and p = 2.05. Our conclusions remain unchanged.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Upper panel: kilonova afterglows from a set of ab initio numerical relativity BNS merger simulations. In these simulations, the kilonova ejecta is of dynamical nature, with resulting kinetic energy profiles shown in Figure 10. Different colors correspond to different EoSs (BLh, LS220, and SLy4) and NS mass ratios q. Good quantitative agreement between the numerical relativity predictions and the observation is obtained. The light curves are computed assuming an ISM density of n ISM = 6 × 10−3 cm−3, and microphysical parameters, ϵ  e  = 10−1, ϵ B = 10−2. Lower panel: effect of the extrinsic parameters (i.e., density and shock microphysics) on the kilonova afterglow emission from equal-mass NS binaries (i.e., q ≈ 1 that is typical of the Galactic population) and different EoSs. For LS220, BLh and SFHo current observations are consistent with n ∼ 6 × 10−3, 5 × 10−3, 5 × 10−3 cm−3, and ϵ B ∼ 10−2, 2 × 10−3, and 10−3, respectively, for a fiducial ϵ  e  = 0.1. In both panels the viewing angle is assumed to be 30° from the polar axis. The bands correspond to light curves with the electron distribution power-law index p varying between 2.05 and 2.15.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Upper panel: the colored lines show kinetic energy profile of the fastest kilonova ejecta as a function of specific momentum Γβ. The dark-red to orange shaded lines show the dynamical ejecta profiles as inferred from ab initio numerical relativity simulations described in Section 7 for different EoS and NS mass ratios q. The blue lines show E KN (>Γβ) ∝ (Γβ)−α  analytical profiles that include the contributions from all types of kilonova ejecta for α = 4, 5, 6, 7, and 9. The black filled circles show kinetic energy inferred from the modeling of the UV/optical/NIR kilonova emission (Villar et al. 2017). The gray squares show short γ-ray burst (SGRB) jets (Wu & MacFadyen 2019). Lower panel: kilonova ejecta profiles in the mass phase space. The green colored area shows the region of the parameter space consistent with a cocoon shock breakout origin of GRB 170817A (Gottlieb et al. 2018). The blue colored area shows the region of the parameter space that is suggestive of a free-neutron component of the ejecta expected to power a short-lived UV/optical transient.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Observed 0.3–10 keV X-ray luminosity (black filled circles) compared to two sources of energy to power the X-ray excess in the compact-object powered scenario: (1) accretion-powered fall-back luminosity, both intrinsic (orange solid line) and observed (red dashed line), i.e., with a correction for absorption by the kilonova ejecta of the form ﹩\propto (1-{e}^{-{(t/{t}_{\mathrm{thin}})}^{2}})﹩, where t thin ≈ 1000 days (Equation (6)); and, (2) magnetar spin-down luminosity (Equation (10), dotted blue line) for B ∼ 109 G to match the level of the observed X-ray emission.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: Comparison of 1 keV flux densities derived in this work (purple circles, derived from the fluxes reported in Table 1), where we do not assume a photon index based on the jet-afterglow modeling, with those calculated by Troja et al. (2022; orange circles) where also the photon index is free for all epochs, as noted in their Table 1. We note that all of the detections are consistent within ≲0.9σ uncertainties at all epochs. The colored bands are the 68%, 97.5%, and 99.8% confidence intervals of the fits obtained from fitting our data including the latest epochs at δ t > 900 days (purple bands, the same as in the right panel of Figure 3) and from fitting all of the data from Troja et al. (2022; in orange) using JetFit, with γ B = 12, n = 0.01 cm−3, and ϵ  e  = 0.1 fixed. Even though these fits were obtained for all of the flux densities derived using their respective spectral indices, for plotting purposes only, we have shown our δ t > 900 day flux densities (in purple) that were obtained using a fixed Γ. The best fits obtained in Troja et al. (2022) are plotted in black lines.
Paper: Evidence for X-Ray Emission in Excess to the Jet-afterglow Decay 3.5 yr after the Binary Neutron Star Merger GW 170817: A New Emission Component
Authors: A. Hajela, R. Margutti, J. S. Bright, K. D. Alexander, B. D. Metzger, V. Nedora, A. Kathirgamaraju, B. Margalit, D. Radice, C. Guidorzi, E. Berger, A. MacFadyen, D. Giannios, R. Chornock, I. Heywood, L. Sironi, O. Gottlieb, D. Coppejans, T. Laskar, Y. Cendes, R. Barniol Duran, T. Eftekhari, W. Fong, A. McDowell, M. Nicholl, X. Xie, J. Zrake, S. Bernuzzi, F. S. Broekgaarden, C. D. Kilpatrick, G. Terreran, V. A. Villar, P. K. Blanchard, S. Gomez, G. Hosseinzadeh, D. J. Matthews, J. C. Rastinejad
Figure caption: One- and two-dimensional projections of the posterior distributions of the JetFit model’s free parameters. Vertical dashed lines mark the 16th, 50th, and 84th percentiles of the marginalized distributions (i.e., the median and 1σ range). The contours are drawn at the 68%, 95%, and 99% credible levels.
Paper: Misalignment of Terrestrial Circumbinary Planets as an Indicator of Their Formation Mechanism
Authors: Anna C. Childs, Rebecca G. Martin
Figure caption: Particle misalignments (left) and nodal phase angles (right) as a function of the semimajor axis at a time of 100 Kyr of integration time with no expansion factor in the systems without Jupiter and Saturn. The size and color of the points are correlated to the body mass. There is not much change to the body masses (which begin at either ≈0.1 M ⊕ or ≈0.01 M ⊕) or inclinations at this time.
Paper: Misalignment of Terrestrial Circumbinary Planets as an Indicator of Their Formation Mechanism
Authors: Anna C. Childs, Rebecca G. Martin
Figure caption: Particle and binary orbits of C30 (upper panels, circular orbit binary with i b0 = 30°) and P60 (lower panels, eccentric orbit binary with i b0 = 60°) at three different times: t = 0, 100 Kyr, and 7 Myr. The binary is shown with black stars, and its orbit is shown edge on.
Paper: Misalignment of Terrestrial Circumbinary Planets as an Indicator of Their Formation Mechanism
Authors: Anna C. Childs, Rebecca G. Martin
Figure caption: Misalignment (left panels, i b for C30 and C60 and i  e  for P60) and eccentricity (right panels) vs. semimajor axis for all the remaining bodies at time t = 7 Myr. The size and color of the points are correlated with the body mass.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption:  Ka-band image of the central 0.8 pc of the galaxy. Sgr A* is indicated as a white filled circle, and all 64 HCRs that we have identified in this region are marked with green crosses. This 33 GHz image was made with baselines from 500 to 4000 kλ, giving an FWHM beam of 0.″08 × 0.″03 and an rms noise of 8 μJy beam−1. The color wedge scales intensity in units of Jy beam−1. In addition to the marked HCRs, some extended features corresponding to fine-scale structures in the Northern Arm, Eastern Arm, and the “mini cavity” of the Sgr A West H II region, which are present in this image, are also labeled. The position of Sgr A* is registered at R.A.(J2000) = 17:45:40.0409, decl.(J2000) = −29:00:28.118 (Reid & Brunthaler 2004) in the equatorial coordinate system.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: (a) Contour image of the magnetar SGR J1745–2900 observed on 2017 October 6 using ALMA at 225.75 GHz with an FWHM beam of 0.″024 × 0.″017 (PA 82°). Contours are σ im × (−5.7, 5.7, 8, 11.3, 16, 22.6, 32, 45.3), where ﹩{\sigma }_{\mathrm{im}}=22﹩                      μJy beam−1. (b) ALMA image of the magnetar SGR J1745–2900 (top right: a point source) and IRS 21 (bottom left: a complex) observed on 2019 October 14 at 318 GHz with an FWHM beam of 0.″087 × 0.″059 (89.°5). Contours are σ im × (−6, 6, 8, 11, 15), where ﹩{\sigma }_{\mathrm{im}}=55﹩                      μJy beam−1. The FWHM beams are illustrated at the bottom-left corner in each image. Numbers on the gray-scale bar are in units of μJy beam−1.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: Images of individual HCRs, color for 44.6 GHz intensity and contours for 33 GHz from an image made with a long-baseline filter of >500 kλ except for HCR 39, which was made with a longer-baseline filter >1000 kλ to separate the point-like source from the contamination of the extended emission associated with the radio core IRS 13E. The IR stars (E2, E3, and E4) detected in the IRS 13E region (Zhu et al. 2020) are marked with white dots (see the HCR 38 and HCR 39 panels). The color wedges scale the intensity of 44.6 GHz emission in units of Jy beam−1. The contours are ﹩{{\sigma }}_{{\rm{i}}{\rm{m}}}\times {2}^{n/2}﹩, where n starts from n 1 until it reaches the source peaks. The values of σ im and n 1 corresponding to the individual HCR image panels are listed in column 11 of Table 2. The bottom-right corners are the FWHM beams at 44.6 and 33 GHz: 0.″08 × 0.″03 (PA = 12°) in blue and 0.″08 × 0.″03 (PA = –11°) in white, respectively.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: (a) The Ka-band image made with the JVLA A-array data using all available baselines, showing the radio structure of HCR 22, a candidate source of particles and energy powering the PWN. The contours are 5 μJy beam−1 × (−4, 4, 5.7, 8, 11.3, 16) with FWMH = 0.″11 × 0.″04, −11° (bottom right). (b) JVLA 9 GHz images at epochs 2014 April 17 (color) and 2020 November 27 (contours). The contours are 50 μJy beam−1 × (64, 80, 96, 112, 128) with FWMH = 0.″36 × 0.″15, −6° (bottom right). The green plus marks the peak position at 33 GHz. The three black ellipses mark the peak positions of the counterpart at 9 GHz at the three observing epochs as labeled. The size of each ellipse scales the 1σ uncertainty of the peak position determined from a 2D-Gaussian fitting. The color wedge scales the intensity in units of Jy beam−1 for the JVLA images. (c) The Chandra X-ray image (angular resolution = 0.″5, from Zhu et al. 2018) of the PWN G359.95–0.04 (Wang et al. 2006). The green box at the tip of the PWN marks the region of HCR 22 as imaged at 9 GHz in panel (b).
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: Images of the radio emission from the microquasar corresponding to the X-ray transient CXOGC J174540.0–290031, observed with the JVLA in the A array at 33 GHz (contours) and 22.5 GHz (colors) on 2015 September 11 and 2005 September 16, respectively. At the bottom-right corner, the FWHM beams of 0.″11 × 0.″04 (−11°) and 0.″2 × 0.″1 (0°) at 33 and 22.5 GHz are shown with the white and filled blue ellipses. Contour values are σ im× (5.7, 8, 11.3, 16, 22.6 and 32), where σ im = 7μJy beam−1. The two plus symbols mark the positions of K40 at 22.5 GHz in 2005 and of HCR 22 at 33 GHz in 2015.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: Averaged spectrum of SGR J1745–2900, made with band-averaged flux densities observed with the JVLA and ALMA (values summarized in Table 3) as well as with ATCA (Shannon & Johnston 2013).
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: (a) The X-ray luminosity variation after the onset of the outburst of SGR J1745–2900; observations by the Chandra X-ray observatory (Rea et al. 2020). (b) 100 MJD bin-averaged radio light curve of the magnetar J1745–2900 for both the millimeter (red dots) and centimeter (black dots) components. In addition to the flux-density measurements from the JVLA and ALMA summarized in Table 3; other telescope data from the literature (Shannon & Johnston 2013; Torne et al. 2017a, 2017b) are included. (c) Detail of ALMA observations in the interval between 2017 October 6 and 2017 October 20 (1626 days after the outburst of SGR 1745-2900 on 2013 April 24) show a day-to-day variability of the magnetar SGR J1745–2900 at 225 GHz displayed as normalized flux densities S MJD−56406/S min (red dots), where the minimum flux density S min  = 0.79 ± 0.08 mJy for the magnetar on MJD 58035. The variability of SGR J1745–2900 during the two-week interval is compared with that of Sgr A* (dark-blue dots); Sgr A* (S min = 3.015 ±0.013 Jy and S  ave  = 3.26 ± 0.09 Jy) is three orders in magnitude more luminous than the magnetar.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: Flux-density distribution of the HCRs at 33 GHz within the central 13″ × 13″ region vs. the GCCRs (Zhao et al. 2020) detected in the GC radio-bright zone (15′ × 15′). The gray histogram represents the 110 GCCRs detected at 5.5 GHz outside Sgr A West. The 64 HCRs (65 components, HCR 49 is double), shown by the hatched histograms, are divided into three types: flat −0.5 < α ≤ 0.2 (red), steep α ≤ − 0.5 (green), and inverted α ≥ 0.2 (blue), according to their radio spectral index determined between 44.6 and 33 GHz, except for three steep-spectrum sources—HCR 22, HCR 32, and HCR 64—which were not detected in the Q-band data used in this paper. The spectral indices for HCR 22 and HCR 32 are determined using the X-band data discussed in this paper. The spectral index for HCR 64, the microquasar, is determined using the K-band data of Zhao et al. (2009) assuming that the source was in a quiescent state during the 2015 observations. The inset panels on the right are the more finely binned individual distributions of the three spectral subsamples. The distribution of the steep-spectrum HCRs is fitted with a Gaussian (red curve).
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: Radial distribution of the surface density of compact radio sources detected at the Galactic center. The red points are the surface-density data ﹩{{\rm{\Sigma }}}_{\mathrm{crs}}^{* }﹩ corrected for a higher equivalent sensitivity cutoff at 5.5 GHz by multiplying the original 33 GHz surface-density data, Σcrs (light-gray points), by a correction factor, η = 2.4, derived from the 33 GHz observations of the HCRs (see the Appendix of this paper). The black points mark the data of GCCRs observed at 5.5 GHz. In the annular zones around R = 3″, a bump in Σcrs is present. The orange line is the best fit using a power law with an index Γ = 1.6 ± 0.2 for the inner region outside of the bump at 1.″5–7″, and the blue line indicates the least-squares fitting to the steeper power law with β = 2.0 ± 0.2 for the outer region. The break radius, R  b , is ∼ 30″, or ∼1.2 pc. The top-right inset shows the surface-density distribution of the HCRs excluding the flat-spectrum sources.
Paper: Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy
Authors: Jun-Hui Zhao, Mark R. Morris, W. M. Goss
Figure caption: The radio-bright zone (RBZ) is divided into 20 annular zones (AZs) along the radial direction from Sgr A*. Spatial distribution of GC compact radio sources or GCCRs (light-blue symbols: crosses for variables and dots for nonvariables) in AZs is displayed over the RBZ (AZ 1–6) (top panel: Figure A1(a)) and Sgr A West (AZ 7–11) (middle panel: Figure A1(b)). The HCRs (light-blue dots) are distributed in the central parsec (AZ 12–20) (bottom panel: Figure A1(c)). The thick red ring marks the 11th ring ((Equation A2)), R(11) = 13″, ∼0.5 pc. In Figures A1(a) and A1b, the black cross with a dot marks the Galactic center transient, the GCT (Zhao et al. 1992). The magnetar J1745–2900 and IRS 13E are labeled in Figure 1Ac.