Journal articles: 'Maximum Luminosity'

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Lu, Wenbin, and Pawan Kumar. "The maximum luminosity of fast radio bursts." Monthly Notices of the Royal Astronomical Society: Letters 483, no. 1 (October 23, 2018): L93—L97. http://dx.doi.org/10.1093/mnrasl/sly200.

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Füllekrug, Martin, Stanislaus Nnadih, Serge Soula, Janusz Mlynarczyk, Micheal Stock, Jeff Lapierre, and Michael Kosch. "Maximum Sprite Streamer Luminosity Near the Stratopause." Geophysical Research Letters 46, no. 21 (November 11, 2019): 12572–79. http://dx.doi.org/10.1029/2019gl084331.

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Kanbur, S. M., M. A. Hendry, and D. Clarke. "Period-luminosity and period-luminosity-colour relations for Mira variables at maximum light." Monthly Notices of the Royal Astronomical Society 289, no. 2 (August 1, 1997): 428–42. http://dx.doi.org/10.1093/mnras/289.2.428.

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Andrei, Alexandre, Bruno Coelho, Leandro L. S. Guedes, and Alexandre Lyra. "The luminosity function of quasars by the Principle of Maximum Entropy." Monthly Notices of the Royal Astronomical Society 488, no. 1 (June 21, 2019): 183–90. http://dx.doi.org/10.1093/mnras/stz1627.

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ABSTRACT We propose a different way to obtain the distribution of the luminosity function of quasars by using the Principle of Maximum Entropy. The input data come from Richard et al 2006 quasar counts, extending up to redshift 5 and limited from apparent magnitude i = 15–19.1 at z ≲ 3 to i = 20.2 for z ≳ 3. Using only few initial data points, the principle allows us to estimate probabilities and hence that luminosity curve. We carry out statistical tests to evaluate our results. The resulting luminosity function compares well to earlier determinations, and our results remain consistent either when the amount or choice of sampled sources is unbiasedly altered. Besides this, we estimate the distribution of the luminosity function for redshifts in which there is only observational data in the vicinity.

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Dexter, A. C., G. Burt, P. K. Ambattu, V. Dolgashev, and R. Jones. "CLIC crab cavity design optimisation for maximum luminosity." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 657, no. 1 (November 2011): 45–51. http://dx.doi.org/10.1016/j.nima.2011.05.057.

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Luri, X., M. O. Mennessier, J. Torra, and F. Figueras. "A new maximum likelihood method for luminosity calibrations." Astronomy and Astrophysics Supplement Series 117, no. 2 (June 1996): 405–15. http://dx.doi.org/10.1051/aas:1996165.

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Vardanyan, Valeri, Daniel Weedman, and Lusine Sargsyan. "SEEKING THE EPOCH OF MAXIMUM LUMINOSITY FOR DUSTY QUASARS." Astrophysical Journal 790, no. 2 (July 8, 2014): 88. http://dx.doi.org/10.1088/0004-637x/790/2/88.

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Veshcherevich, V. G., V. A. Lebedev, P. V. Logachev, and V. P. Yakovlev. "Monochromatization as the way to maximum luminosity B-factories." Nuclear Physics B - Proceedings Supplements 27 (June 1992): 12–26. http://dx.doi.org/10.1016/0920-5632(92)90028-q.

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Mummery, Andrew. "A maximum X-ray luminosity scale of disc-dominated tidal destruction events." Monthly Notices of the Royal Astronomical Society 504, no. 4 (April 26, 2021): 5144–54. http://dx.doi.org/10.1093/mnras/stab1187.

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ABSTRACT We develop a model describing the dynamical and observed properties of disc-dominated tidal disruption events (TDEs) around black holes with the lowest masses (M ≲ few × 106M⊙). TDEs around black holes with the lowest masses are most likely to reach super-Eddington luminosities at early times in their evolution. By assuming that the amount of stellar debris that can form into a compact accretion disc is set dynamically by the Eddington luminosity, we make a number of interesting and testable predictions about the observed properties of bright soft-state X-ray TDEs and optically bright, X-ray dim TDEs. We argue that TDEs around black holes of the lowest masses will expel the vast majority of their gravitationally bound debris into a radiatively driven outflow. A large-mass outflow will obscure the innermost X-ray producing regions, leading to a population of low black hole mass TDEs that are only observed at optical and UV energies. TDE discs evolving with bolometric luminosities comparable to their Eddington luminosity will have near constant (i.e. black hole mass independent) X-ray luminosities, of order LX, max ≡ LM ∼ 1043 − 1044 erg s−1. The range of luminosity values stems primarily from the range of allowed black hole spins. A similar X-ray luminosity limit exists for X-ray TDEs in the hard (Compton scattering dominated) state, and we therefore predict that the X-ray luminosity of the brightest X-ray TDEs will be at the scale LM(a) ∼ 1043 − 1044 erg s−1, independent of black hole mass and accretion state. These predictions are in strong agreement with the properties of the existing population (∼40 sources) of observed TDEs.

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Gieles, M., S. S. Larsen, N. Bastian, and I. T. Stein. "The luminosity function of young star clusters: implications for the maximum mass and luminosity of clusters." Astronomy & Astrophysics 450, no. 1 (April 2006): 129–45. http://dx.doi.org/10.1051/0004-6361:20053589.

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Tiwari, Sanjiv K., Lucy A. Wilkerson, Navdeep K. Panesar, Ronald L. Moore, and Amy R. Winebarger. "Dominance of Bursty over Steady Heating of the 4–8 MK Coronal Plasma in a Solar Active Region: Quantification Using Maps of Minimum, Maximum, and Average Brightness." Astrophysical Journal 942, no. 1 (December 28, 2022): 2. http://dx.doi.org/10.3847/1538-4357/aca541.

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Abstract A challenge in characterizing active region (AR) coronal heating is in separating transient (bursty) loop heating from the diffuse background (steady) heating. We present a method of quantifying coronal heating’s bursty and steady components in ARs, applying it to Fe xviii (hot 94) emission of an AR observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The maximum-, minimum-, and average-brightness values for each pixel, over a 24 hr period, yield a maximum-brightness map, a minimum-brightness map, and an average-brightness map of the AR. Running sets of such three maps come from repeating this process for each time step of running windows of 20, 16, 12, 8, 5, 3, 1, and 0.5 hr. From each running window’s set of three maps, we obtain the AR’s three corresponding luminosity light curves. We find (1) the time-averaged ratio of minimum-brightness-map luminosity to average-brightness-map luminosity increases as the time window decreases, and the time-averaged ratio of maximum-brightness-map luminosity to average-brightness-map luminosity decreases as the window decreases; (2) for the 24 hr window, the minimum-brightness map’s luminosity is 5% of the average-brightness map’s luminosity, indicating that at most 5% of the AR’s hot 94 luminosity is from heating that is steady for 24 hr; (3) this upper limit on the fraction of the hot 94 luminosity from steady heating increases to 33% for the 30 minute running window. This requires that the heating of the 4–8 MK plasma in this AR is mostly in bursts lasting less than 30 minutes: at most a third of the heating is steady for 30 minutes.

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Bhardwaj, Anupam, Shashi Kanbur, Shiyuan He, Marina Rejkuba, Noriyuki Matsunaga, Richard de Grijs, Kaushal Sharma, et al. "Multiwavelength Period–Luminosity and Period–Luminosity–Color Relations at Maximum Light for Mira Variables in the Magellanic Clouds." Astrophysical Journal 884, no. 1 (October 8, 2019): 20. http://dx.doi.org/10.3847/1538-4357/ab38c2.

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Loveday, Jon. "Galaxy and Mass Assembly (GAMA): luminosity function evolution." Proceedings of the International Astronomical Union 10, S306 (May 2014): 40–44. http://dx.doi.org/10.1017/s174392131401357x.

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AbstractWe describe modifications to the joint stepwise maximum likelihood method of Cole (2011) in order to simultaneously fit the GAMA-II galaxy luminosity function (LF), corrected for radial density variations, and its evolution with redshift. The whole sample is reasonably well-fit with luminosity (Q) and density (P) evolution parameters Q, P ≈ 0.8, 1.7. Red galaxies show larger luminosity but smaller density evolution than blue galaxies, as expected.

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Foukal, Peter. "Solar Irradiance Variability and Luminosity Changes." Highlights of Astronomy 10 (1995): 294–95. http://dx.doi.org/10.1017/s1539299600011242.

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This review presents a discussion of radiometrie measurements of solar total irradiance variation, ΔS, on time scales of days, to the 15-year extent of present measurements. It does not cover variations in spectral irradiance, particularly the relatively large solar UV and EUV flux variations of great importance in studies of trends in stratospheric ozone, and of upper atmospheric heating variations.Analysis of the pyrheliometry of ΔS carried out from the Solar Maximum Mission, Nimbus-7 and ERB S satellites has shown that a) the sun brightens by 0.05 - 0.1% around activity maximum and; b) it dims by up to approximately 0.2% when large sunspot groups cross the disc. Empirical models of ΔS based on areas and photometric contrasts of sunspots, and on proxies of facular area, are remarkably successful in matching the observed record of ΔS, on time scales between days and the full 15- year record available since 1978. These models indicate that the opposite contributions of sunspots and faculae in active regions roughly balance over time scales of years, and the net solar brightening observed around peak activity is caused by increased emission from the photospheric magnetic network.

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Zaninetti, Lorenzo. "The Truncated Lindley Distribution with Applications in Astrophysics." Galaxies 7, no. 2 (May 29, 2019): 61. http://dx.doi.org/10.3390/galaxies7020061.

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This paper reviews the Lindley distribution and then introduces the scale and the double truncation. The unknown parameters of the truncated Lindley distribution are evaluated with the maximum likelihood estimators. An application of the Lindley distribution with scale is done to the initial mass function for stars. The magnitude version of the Lindley distribution with scale is applied to the luminosity function for the Sloan Digital Sky Survey (SDSS) galaxies and to the photometric maximum of the 2MASS Redshift Survey (2MRS) galaxies. The truncated Lindley luminosity function allows to model the Malquist bias of the 2MRS galaxies.

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Lazovik, Yaroslav A., and Alexey S. Rastorguev. "Calibrating the Galactic Cepheid Period–Luminosity Relation from the Maximum-likelihood Technique." Astronomical Journal 160, no. 3 (August 26, 2020): 136. http://dx.doi.org/10.3847/1538-3881/aba627.

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Parnovsky, S., and I. Izotova. "Compact galaxies with active star formation: statistical properties of subsamples with the Hβ line emission flow threshold." Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 65 (2022): 40–44. http://dx.doi.org/10.17721/btsnua.2022.65.40-44.

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We study the dependence of the luminosity of starburst galaxy on the young age (< 10 Myr) of star formation burst and metallicity. We also study the luminosity function (LF) for different subsamples of starburst galaxies. These subsamples with different threshold values of the Hβ emission line fluxes were formed from a sample of 14,000 local compact galaxies with active star formation. We obtain relations for a temporal evolution of luminosity-to-stellar mass of young stellar population ratio on the starburst age and metallicity. Luminosity functions for subsamples of galaxies with Hβ fluxes exceeding a certain threshold value are shown to differ from Schechter’s LF at the high luminosity end. They are adequately described by a log-normal function with parameters determined by the maximum likelihood method. The results confirm and complement the conclusions made in previous studies of the starburst galaxy samples.

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Sollerman, J., S. Yang, D. Perley, S. Schulze, C. Fremling, M. Kasliwal, K. Shin, and B. Racine. "Maximum luminosities of normal stripped-envelope supernovae are brighter than explosion models allow." Astronomy & Astrophysics 657 (January 2022): A64. http://dx.doi.org/10.1051/0004-6361/202142049.

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Context. Stripped-envelope supernovae (SE SNe) of Type Ib and Type Ic are thought to be the result of explosions of massive stars that have lost their outer envelopes. The favored explosion mechanism is via core-collapse, with the shock later revived by neutrino heating. However, there is an upper limit to the amount of radioactive 56Ni that such models can accommodate. Recent studies in the literature point to a tension between the maximum luminosity from such simulations and the observations. Aims. We used a well-characterized sample of SE SNe from the Zwicky Transient Facility (ZTF) Bright Transient Survey (BTS) to scrutinize the observational caveats regarding estimates of the maximum luminosity (and thus the amount of ejected radioactive nickel) for the sample members. Methods. We employed the strict selection criteria for the BTS to collect a sample of spectroscopically classified normal Type Ibc SNe, for which we used the ZTF light curves to determine the maximum luminosity. We culled the sample further based on data quality, shape of the light curves, distances, and colors. Then we examined the uncertainties that may affect the measurements. The methodology of the sample construction based on this BTS sample can be used for other future investigations. Results. We analyzed the observational data, consisting of optical light curves and spectra, for the selected sub-samples. In total, we used 129 Type Ib or Type Ic BTS SNe with an initial rough luminosity distribution peaking at Mr = −17.61 ± 0.72, and where 36% are apparently brighter than the theoretically predicted maximum brightness of Mr = −17.8. When we further culled this sample to ensure that the SNe are normal Type Ibc with good LC data within the Hubble flow, the sample of 94 objects gives Mr = −17.64 ± 0.54. A main uncertainty in absolute magnitude determinations for SNe is the host galaxy extinction correction, but the reddened objects only get more luminous after corrections. If we simply exclude red objects, or those with unusual or uncertain colors, then we are left with 14 objects at Mr = −17.90 ± 0.73, whereof a handful are most certainly brighter than the suggested theoretical limit. The main result of this study is thus that normal SNe Ibc do indeed reach luminosities above 1042.6 erg s−1, which is apparently in conflict with existing explosion models.

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Hekker, S., G. C. Angelou, Y. Elsworth, and S. Basu. "Mirror principle and the red-giant bump: the battle of entropy in low-mass stars." Monthly Notices of the Royal Astronomical Society 492, no. 4 (January 20, 2020): 5940–48. http://dx.doi.org/10.1093/mnras/staa176.

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ABSTRACT The evolution of low-mass stars into red giants is still poorly understood. During this evolution the core of the star contracts and, simultaneously, the envelope expands – a process known as the ‘mirror’. Additionally, there is a short phase where the trend for increasing luminosity is reversed. This is known as the red giant branch bump. We explore the underlying physical reasons for these two phenomena by considering the specific entropy distribution in the star and its temporal changes. We find that between the luminosity maximum and luminosity minimum of the bump there is no mirror present and the star is fully contracting. The contraction is halted and the star regains its mirror when the hydrogen-burning shell reaches the mean molecular weight discontinuity. This marks the luminosity minimum of the bump.

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Chen, Hai-Liang, T. E. Woods, L. R. Yungelson, Luciano Piersanti, M. Gilfanov, and Zhanwen Han. "Comprehensive models of novae at metallicity Z = 0.02 and Z = 10−4." Monthly Notices of the Royal Astronomical Society 490, no. 2 (September 21, 2019): 1678–92. http://dx.doi.org/10.1093/mnras/stz2644.

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ABSTRACT Novae are the observational manifestations of thermonuclear runaways on the surface of accreting white dwarfs (WDs). Although novae are an ubiquitous phenomenon, their properties at low metallicity are not well understood. Using the publicly-available stellar evolution code Modules for Experiments in Stellar Astrophysics (mesa), we model the evolution of accreting carbon–oxygen WDs and consider models that accrete matter with metallicity Z = 0.02 or 10−4. We consider both models without mixing and with matter enriched by CO-elements assuming that mixing occurs in the process of accretion (with mixing fraction 0.25). We present and contrast ignition mass, ejected mass, recurrence period, and maximum luminosity of novae for different WD masses and accretion rates for these metallicities and mixing cases. We find that models with Z = 0.02 have ignition masses and recurrence periods smaller than models with low Z, while the ejected mass and maximum luminosity are larger. Retention efficiency during novae outbursts decreases with increasing metallicity. In our implementation, inclusion of mixing at the H/He interface reduces accreted mass, ejected mass, and recurrence period as compared to the no-mixing case, while the maximum luminosity becomes larger. Retention efficiency is significantly reduced, becoming negative in most of our models. For ease of use, we provide a tabular summary of our results.

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Chesneau, O., T. Verhoelst, B. Lopez, L. B. F. M. Waters, Ch Leinert, W. Jaffe, R. Köhler, A. de Koter, and C. Dijkstra. "The mid-IR spatially resolved environment of OH 26.5+0.6 at maximum luminosity." Astronomy & Astrophysics 435, no. 2 (April 29, 2005): 563–74. http://dx.doi.org/10.1051/0004-6361:20042235.

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Secker, Jeff, and William E. Harris. "A maximum likelihood analysis of globular cluster luminosity distributions in the Virgo ellipticals." Astronomical Journal 105 (April 1993): 1358. http://dx.doi.org/10.1086/116515.

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van den Bergh, Sidney, and John Pazder. "The luminosity of supernovae of Type Ia. I - Apparent magnitudes at maximum light." Astrophysical Journal 390 (May 1992): 34. http://dx.doi.org/10.1086/171256.

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Méndez, Roberto H. "The Planetary Nebulae Luminosity Function (PNLF): current perspectives." Proceedings of the International Astronomical Union 12, S323 (October 2016): 298–302. http://dx.doi.org/10.1017/s1743921317000461.

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AbstractThis paper starts with a brief historical review about the PNLF and its use as a distance indicator. Then the PNLF distances are compared with Surface Brightness Fluctuations (SBF) distances and Tip of the Red Giant Branch (TRGB) distances. A Monte Carlo method to generate simulated PNLFs is described, leading to the last subject: recent progress in reproducing the expected maximum final mass in old stellar populations, a stellar astrophysics enigma that has been challenging us for quite some time.

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Yamanaka, M., K. S. Kawabata, K. Maeda, M. Tanaka, M. Yoshida, T. Hattori, K. Nomoto, T. Komatsu, and T. Okushima. "Late-Phase Observations of a Super-Chandrasekhar SN Ia." Proceedings of the International Astronomical Union 7, S281 (July 2011): 319–21. http://dx.doi.org/10.1017/s1743921312015281.

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AbstractA super-Chandrasekhar (SC) supernova (SN) has an extremely high luminosity and a slow decline rate of the light curve in the early-phase. We present late-phase observations of the SC SN 2009dc. We find that the optical luminosity a year after maximum is much fainter than that expected from its early luminosity. We attempt to fit the analytic light curve model to the observations using Arnett's rule. The model successfully explains the light curves until 120 days. This suggests that the extremely high luminosity originates from the 56Ni decay. We suggest that the late-phase decline would be caused by dust formation. The existence of strong carbon features in early-phase spectra would support this scenario. We also find a blend of [Ca ii] and [Ni ii] in its late-phase spectrum. This indicates that the calcium is distributed in the inner layer along with nickel and iron. We conclude that the mixing may occur in the inner parts of the ejecta.

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Chevalier, Roger A. "Supernova interaction with dense mass loss." Proceedings of the International Astronomical Union 9, S296 (January 2013): 95–102. http://dx.doi.org/10.1017/s1743921313009290.

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AbstractSupernovae of Type IIn (narrow line) appear to be explosions that had strong mass loss before the event, so that the optical luminosity is powered by the circumstellar interaction. If the mass loss region has an optical depth >c/vs, where vs is the shock velocity, the shock breakout occurs in the mass loss region and a significant fraction of the explosion energy can be radiated. The emission from the superluminous SN 2006gy and the normal luminosity SN 2011ht can plausibly be attributed to shock breakout in a wind, with SN 2011ht being a low energy event. Superluminous supernovae of Type I may derive their luminosity from interaction with a mass loss region of limited extent. However, the distinctive temperature increase to maximum luminosity has not been clearly observed in Type I events. Suggested mechanisms for the strong mass loss include pulsational pair instability, gravity-waves generated by instabilities in late burning phases, and binary effects.

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Antonialli-Junior, William Fernando, and Ingrid Guimarães. "Aggregation Behavior in Spiderlings: a Strategy for Increasing Life Expectancy in Latrodectus geometricus (Araneae: Theridiidae)." Sociobiology 59, no. 2 (September 26, 2014): 463. http://dx.doi.org/10.13102/sociobiology.v59i2.611.

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Studies on the biology of Latrodectus geometricus are scarce, especially on the behavior and life expectancy of the species. In this study we investigated the importance of the aggregation behavior of juveniles on life expectancy and longevity of the species. Egg sacs were collected in the urban area of Dourados- MS and transferred to the laboratory. The spiderlings hatched were separated into two groups: spiderlings aggregated and isolated, kept in the presence of luminosity. The same tests were run with egg sacs deprived of luminosity. A calculation of entropy was performed for all cases. Individuals grouped held under light exposure showed 14.3 days of life expectancy and 46 maximum longevity and 14.8 days of life expectancy and 32 days of longevity when isolated. For individuals grouped and deprived of light life expectancy was 29.8 days and maximum longevity 85 days and 19.3 days of life expectancy and 26 days of maximum longevity when isolated. The entropy of individuals kept in the presence of light, when grouped was H=0.692 and when isolated H=0.377. For individuals deprived of light, the entropy was H = 0.628 when kept grouped and H = 0.143 when isolated. Therefore it is concluded that the aggregation behavior and luminosity influence the longevity and life expectancy of spiderlings. Cannibalism must be a strategy to acquire food reserves contributing to the survival of a small number of individuals.

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Guépin, Claire, Benoît Cerutti, and Kumiko Kotera. "Proton acceleration in pulsar magnetospheres." Astronomy & Astrophysics 635 (March 2020): A138. http://dx.doi.org/10.1051/0004-6361/201936816.

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Pulsars have been identified as good candidates for the acceleration of cosmic rays, up to ultra-high energies. However, a precise description of the acceleration processes at play is still to be established. Using 2D particle-in-cell simulations, we study proton acceleration in axisymmetric pulsar magnetospheres. Protons and electrons are extracted from the neutron star surface by the strong electric field induced by the rotation of the star, and electrons and positrons are produced in the magnetosphere through pair production process. As pair production has a crucial impact on electromagnetic fields, on gaps and thus on particle acceleration, we study its influence on the maximum energy and luminosity of protons escaping the magnetosphere. Protons are accelerated and escape in all our simulations. However, the acceleration sites are different for the protons and the pairs. As shown in previous studies, pairs are accelerated to their highest energies at the Y-point and in the equatorial current sheet, where magnetic reconnection plays an important role. In contrast, protons gain most of their kinetic energy below the light-cylinder radius within the separatrix current layers, but they are not confined within the equatorial current sheet. Their maximum Lorentz factors can reach 15% to 75% of the maximum Lorentz factor obtained by acceleration through the full vacuum potential drop from pole to equator, and increase with decreasing pair production. Their luminosity can reach 0.2% to 4% of the theoretical spin down luminosity of an aligned pulsar, and the minimum luminosity is obtained at the transition between the force-free and electrosphere regimes. These estimates support that millisecond pulsars could accelerate cosmic rays up to PeV energies and that new born millisecond pulsars could accelerate cosmic rays up to ultra-high energies.

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McNamara, D. H., and John M. Powell. "A Theoretical Period-Luminosity Relation of Dwarf Cepheids." International Astronomical Union Colloquium 138 (1993): 437–38. http://dx.doi.org/10.1017/s025292110002087x.

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Dwarf Cepheids (large-amplitude δ Sct variables and SXPhe variables in the GCVS) are late A-type stars near light maximum and early-F stars near light minimum. In the lower part of the instability strip where these stars are found the pulsation constant Q varies only slightly. As pointed out by Andreasen, Hejlesen, and Petersen (1983) this makes it easy to transform a theoretical HR or alternatively a (logTe, logg) diagram to a theoretical logTe, logP0) diagram by the use of the relation. This follows from the equations:where P0 is the fundamental period of pulsation. The periods, of course, can be determined with very high accuracy.

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Li, Siyang, Stefano Casertano, and Adam G. Riess. "A Maximum Likelihood Calibration of the Tip of the Red Giant Branch Luminosity from High Latitude Field Giants Using Gaia Early Data Release 3 Parallaxes." Astrophysical Journal 939, no. 2 (November 1, 2022): 96. http://dx.doi.org/10.3847/1538-4357/ac7559.

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Abstract The calibration of the tip of the red giant branch (TRGB) in the I band has a direct role in determinations of the Hubble constant, a subject of recent interest due to the discrepancy between direct and indirect estimates of its value. We present a maximum likelihood method designed to obtain an independent calibration of the brightness of TRGB using Gaia parallaxes from the Early Data Release 3 (EDR3) of Milky Way field giants at high Galactic latitude. We adopt simple parameterizations for the Milky Way stellar luminosity function and density law and optimize the likelihood of the observed sample as a function of those parameters. Using parameters to partially constrain the luminosity function from other galaxies similar to the Milky Way for which high-quality TRGB data are available, we find values of the TRGB magnitude of M I TRGB = − 3.91 ± 0.05 (stat) ± 0.09 (sys) mag, where the systematic uncertainty covers the range of shape parameters found in our Milky Way sample and in reference galaxies. While APASS Data Release 9 all-sky photometry is insufficient to provide a reliable constraint on the shape of the Milky Way luminosity function, we estimate that the photometry from Gaia Data Release 3 (mid-2022) will allow better constraints on the shape, and lower statistical uncertainties on the tip by a factor of 3. With the expected releases of improved parallax measurements from Gaia, the method of calibrating the TRGB luminosity from field giants is expected to reach ∼0.01 mag uncertainty, which is an important step toward a precise TRGB-based determination of the Hubble constant.

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Ceraj, L., V. Smolčić, I. Delvecchio, M. Novak, G. Zamorani, J. Delhaize, E. Schinnerer, E. Vardoulaki, and N. Herrera Ruiz. "The VLA-COSMOS 3 GHz Large Project: Star formation properties and radio luminosity functions of AGN with moderate-to-high radiative luminosities out to z∼ 6." Astronomy & Astrophysics 620 (December 2018): A192. http://dx.doi.org/10.1051/0004-6361/201833935.

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We have studied a sample of 1604 moderate-to-high radiative luminosity active galactic nuclei (HLAGN) selected at 3 GHz within the VLA-COSMOS 3 GHz Large Project. These were classified by combining multiple AGN diagnostics: X-ray data, mid-infrared data and broadband spectral energy distribution fitting. We decomposed the total radio 1.4 GHz luminosity (L1.4 GHz, TOT) into the emission originating from star formation and AGN activity by measuring the excess in L1.4 GHz, TOT relative to the infrared-radio correlation of star-forming galaxies. To quantify the excess, for each source we calculated the AGN fraction (fAGN) defined as the fractional contribution of AGN activity to L1.4 GHz, TOT. The majority of the HLAGN, (68.0 ± 1.5)%, are dominated by star-forming processes (fAGN ≤ 0.5), while (32.0 ± 1.5)% are dominated by AGN-related radio emission (0.5 < fAGN ≤ 1). We used the AGN-related 1.4 GHz emission to derive the 1.4 GHz AGN luminosity functions of HLAGN. By assuming pure density and pure luminosity evolution models we constrained their cosmic evolution out to z ∼ 6, finding Φ*(z)∝(1 + z)(2.64 ± 0.10)+(−0.61 ± 0.04)z and L*(z)∝(1 + z)(3.97 ± 0.15)+(−0.92 ± 0.06)z. These evolutionary laws show that the number and luminosity density of HLAGN increased from higher redshifts (z ∼ 6) up to a maximum in the redshift range 1 < z < 2.5, followed by a decline toward local values. By scaling the 1.4 GHz AGN luminosity to kinetic luminosity using the standard conversion, we estimate the kinetic luminosity density as a function of redshift. We compare our result to the semi-analytic models of radio mode feedback, and find that this feedback could have played an important role in the context of AGN-host co-evolution in HLAGN which shows evidence of AGN-related radio emission (fAGN > 0).

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Fiore, A., S. Benetti, M. Nicholl, A. Reguitti, E. Cappellaro, S. Campana, S. Bose, et al. "Close, bright, and boxy: the superluminous SN 2018hti." Monthly Notices of the Royal Astronomical Society 512, no. 3 (March 17, 2022): 4484–502. http://dx.doi.org/10.1093/mnras/stac744.

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ABSTRACT SN 2018hti was a very nearby (z = 0.0614) superluminous supernova with an exceedingly bright absolute magnitude of −21.7 mag in r band at maximum. The densely sampled pre-maximum light curves of SN 2018hti show a slow luminosity evolution and constrain the rise time to ∼50 rest-frame d. We fitted synthetic light curves to the photometry to infer the physical parameters of the explosion of SN 2018hti for both the magnetar and the CSM-interaction scenarios. We conclude that one of two mechanisms could be powering the luminosity of SN 2018hti; interaction with ∼10 M⊙ of circumstellar material or a magnetar with a magnetic field of Bp∼ 1.3 × 1013 G, and initial period of Pspin∼ 1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ${\sim}40\, \mathrm{M}_\odot$ progenitor star.

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Inoue, H. "X-ray Bursting Neutron Stars." Symposium - International Astronomical Union 125 (1987): 233–43. http://dx.doi.org/10.1017/s0074180900160802.

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The maximum peak luminosity of the X-ray bursts from a burster is most likely interpreted as the Eddington luminosity of a helium-rich envelope surrounding a neutron star. If this interpretation is true, we can obtain a relation between the mass and the radius of the neutron star in terms of the maximum effective temperature of bursts. On the other hand, the most naive understanding of the origin of the 4.1 keV absorption line often detected in X-ray burst spectra gives us another relation of the neutron star mass with its radius. By solving two simultaneous equations, we can determine the values of the mass and the radius of the neutron star, respectively. However, the result is critical to every neutron star model currently considered.The persistent emissions from X-ray bursters are also discussed.

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Christlein, Daniel, Eric Gawiser, Danilo Marchesini, and Nelson Padilla. "Introducing the photometric maximum likelihood method: galaxy luminosity functions atz < 1.2in MUSYC-ECDFS." Monthly Notices of the Royal Astronomical Society 400, no. 1 (November 21, 2009): 429–50. http://dx.doi.org/10.1111/j.1365-2966.2009.15474.x.

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Gómez, A. E., X. Luri, M. O. Mennessier, J. Torra, F. Figueras, and F. Royer. "The Luminosity Calibration of the HR Diagram." Highlights of Astronomy 11, no. 1 (1998): 558. http://dx.doi.org/10.1017/s1539299600022139.

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An extensive work on the luminosity calibration of the HR diagram has been performed using the LM method based on the Maximum Likelihood estimation (Luri et al. 1996). The method uses all available information: Hipparcos parallax and proper motion data as well as radial velocities and some measured spectroscopic or photometric parameters related to luminosity. On the other hand, the method takes into account the censorship of the sample and the errors of the data. Finally, it is able to identify and separate in a given sample, groups with different luminosity, kinematical or spatial characteristics providing not only the corresponding luminosity calibration relationship, but also improved individual absolute magnitude estimates.In order to asses how reliable the luminosity calibrations based on the MK spectral classification are, the LM method has been applied to a sample of B to K stars with MK classification selected from the Hipparcos survey. All known binaries, variables and spectroscopically peculiar stars were removed from the sample. The final sample contains 22054 stars. Our results show that the relation between absolute magnitude and luminosity class has a large intrinsic dispersion. As a consequence, the assignation to a star of a mean absolute magnitude given by a MK classification calibration is a rough procedure. It is preferable to use the individual absolute magnitudes estimated using all the available information for each star, like the estimates provided by the LM method (Gómez et al. 1997).

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Mishra, Wageesh, Nandita Srivastava, Yuming Wang, Zavkiddin Mirtoshev, Jie Zhang, and Rui Liu. "Mass loss via solar wind and coronal mass ejections during solar cycles 23 and 24." Monthly Notices of the Royal Astronomical Society 486, no. 4 (April 23, 2019): 4671–85. http://dx.doi.org/10.1093/mnras/stz1001.

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ABSTRACT Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind and episodic stellar coronal mass ejections (CMEs). We investigate the mass loss rate via solar wind and CMEs as a function of solar magnetic variability represented in terms of sunspot number and solar X-ray background luminosity. We estimate the contribution of CMEs to the total solar wind mass flux in the ecliptic and beyond, and its variation over different phases of the solar activity cycles. The study exploits the number of sunspots observed, coronagraphic observations of CMEs near the Sun by SOHO/LASCO, in situ observations of the solar wind at 1 AU by WIND, and GOES X-ray flux during solar cycles 23 and 24. We note that the X-ray background luminosity, occurrence rate of CMEs and ICMEs, solar wind mass flux, and associated mass loss rates from the Sun do not decrease as strongly as the sunspot number from the maximum of solar cycle 23 to the next maximum. Our study confirms a true physical increase in CME activity relative to the sunspot number in cycle 24. We show that the CME occurrence rate and associated mass loss rate can be better predicted by X-ray background luminosity than the sunspot number. The solar wind mass loss rate which is an order of magnitude more than the CME mass loss rate shows no obvious dependency on cyclic variation in sunspot number and solar X-ray background luminosity. These results have implications for the study of solar-type stars.

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Haller, Joseph W., and Marcia J. Rieke. "A Search for Variable Stars at the Galactic Center." Symposium - International Astronomical Union 136 (1989): 487–92. http://dx.doi.org/10.1017/s0074180900186942.

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A study of the Galactic Center stellar population is continuing with a sensitive 2μm CCD camera. Using a 64 × 64 detector array, background limited images are recorded with modest amounts of observing time (tobs ≈ 20 sec to reach K=13). Magnitudes have been extracted using DAOPHOT from repeated imaging of the central 5′ × 5′ to search among approximately 1500 stars for long period variables (LPV's, P > 200d), particularily Miras. Miras have a well defined period-luminosity relationship as well as one in period-mass. This program investigates the nature of highly luminous stars at the Galactic Center. Presently 12 variables have been found and have several characteristics consistent with Miras. They have a maximum bolometric luminosity of −4.4 mag, which supports the case that high luminosity stars in the central 6 pc are young supergiants.

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Saka, O., O. Watanabe, K. Okada, and D. N. Baker. "A slow mode wave as a possible source of Pi 2 and associated particle precipitation: a case study." Annales Geophysicae 17, no. 5 (May 31, 1999): 674–81. http://dx.doi.org/10.1007/s00585-999-0674-4.

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Abstract. An intensification of auroral luminosity referred to as an auroral break-up often accompanies the onset of geomagnetic pulsation (Pi 2) at the dip-equator. One such auroral break-up occurred at 2239 UT on 16 June, 1986, being accompanied by weak substorm activity (AE~50 nT) which was recorded in all-sky image of Syowa Station, Antarctica (66.2°S, 71.8°E in geomagnetic coordinates). The associated Pi 2 magnetic pulsation was detected by a fluxgate magnetometer in the afternoon sector at the dip-equator (Huancayo, Peru; 1.44°N, 355.9° in geomagnetic coordinates; 12.1°S, 75.2°W in geographic coordinates; L=1.00). In spite of the large separation of the two stations in longitude and latitude, the auroral break-up and subsequent luminosity modulation were seen to be correlated with the wave form of the ground Pi 2 pulsation. This occurred in such a way that the luminosity maximum was seen to occur at the phase of maximum amplitudes of Pi 2 wave form. We argue that the observed correlation could be interpreted as indicating a Pi 2-modulation of a field-aligned acceleration of the low energy electrons that may occur near the equator of the midnight magnetosphere.Key words. Magnetospheric physics (auroral phenomena; energetic particles · precipitating; MHD waves and instabilities)

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Yusupova, R. М., G. R. Muchtarova, and R. N. Izmailov. "EDDINGTON LUMINOSITY LIMIT FOR MASSLESS WORMHOLES WITH SCALAR FIELD." Izvestia Ufimskogo Nauchnogo Tsentra RAN, no. 1 (March 28, 2022): 21–24. http://dx.doi.org/10.31040/2222-8349-2022-0-1-21-24.

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Most astrophysical objects growth by mass accretion. The almost universal presence of interstellar matter generally leads to the formation around compact objects of accretion disks. The emission of the radiation from the disk is determined by the external gravitational potentials of the central massive object, which in turn are essentially determined by its nature – neutron star, black hole, wormhole or naked singularity. Hence the astrophysical observations of the emission spectra from accretion disks may lead to the possibility of directly testing the physical and astrophysical properties of the compact general relativistic objects that have generated the disk via their gravitational field. The accretion process proceeds due to the viscosity caused by the turbulent motions of matter in the accretion disks. In turn, disks have an important property – luminosity, which today allows indirect observation of astrophysical compact objects. In this work, calculations are performed to determine the Eddington luminosity limit of an accretion disk formed around a massless wormhole. The dependence of the limiting luminosity in the throat region and at infinity on the dilatonic, electric and magnetic charges for the Goulart wormhole was established. An upper limit was also obtained for the dilatonic charge, at which the maximum value of Eddington's luminosity is reached. As a result, it was found that with an increase in the dilatonic charge, the value of the Eddington luminosity limit increases.

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Hou, X., Y. You, L. Ji, R. Soria, S. N. Zhang, M. Y. Ge, L. Tao, et al. "Monte Carlo Simulations on Possible Collimation Effects of Outflows to Fan Beam Emission of Ultraluminous Accreting X-Ray Pulsars." Astrophysical Journal 941, no. 2 (December 1, 2022): 126. http://dx.doi.org/10.3847/1538-4357/aca2a3.

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Abstract Pulsating ultraluminous X-ray sources (PULXs) are accreting pulsars with apparent X-ray luminosity exceeding 1039 erg s−1. We perform Monte Carlo simulations to investigate whether a high collimation effect (or strong beaming effect) is dominant in the presence of accretion outflows, for the fan beam emission of the accretion column of the neutron stars in PULXs. We show that the three nearby PULXs (RX J0209.6−7427, Swift J0243.6+6124, and SMC X-3), namely, the Three Musketeers here, have their main pulsed emission not strongly collimated even if strong outflows exist. This conclusion can be extended to the current sample of extragalactic PULXs, if accretion outflows are commonly produced from them. This means that the observed high luminosity of PULXs is indeed intrinsic, which can be used to infer the existence of very strong surface magnetic fields of ∼1013–14 G, possibly multipole fields. However, if strong outflows are launched from the accretion disks in PULXs as a consequence of disk spherization by radiation pressure, regular dipole magnetic fields of ∼1012 G may be required, comparable to that of the Three Musketeers, which have experienced large luminosity changes from well below their Eddington limit (2 × 1038 erg s−1 for an NS) to super-Eddington and whose maximum luminosity fills the luminosity gap between Galactic pulsars and extragalactic PULXs.

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Elebert, P., P. J. Callanan, L. Russell, and S. E. Shaw. "Optical, ultraviolet and X-ray analysis of the black hole candidate BG Geminorum." Proceedings of the International Astronomical Union 2, S238 (August 2006): 361–62. http://dx.doi.org/10.1017/s1743921307005455.

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AbstractWe present the first high resolution optical spectrum of the black hole candidate BG Geminorum, as well as UV spectroscopy from the Hubble Space Telescope, and X-ray data from INTEGRAL. The UV spectra suggest the presence of material in BG Gem with velocities possibly as high as ∼1000 km s−1, suggesting an origin at a distance of ∼0.7 R⊙ from a 3.5 M⊙ object; if real, this would be strong evidence that the primary in BG Gem is indeed a black hole. In contrast, the upper limit provided by the INTEGRAL data gives a maximum X-ray luminosity of only ∼0.1 of the Eddington luminosity.

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Ravi, Vikram, Hannah Dykaar, Jackson Codd, Ginevra Zaccagnini, Dillon Dong, Maria R. Drout, B. M. Gaensler, Gregg Hallinan, and Casey Law. "FIRST J153350.8+272729: The Radio Afterglow of a Decades-old Tidal Disruption Event." Astrophysical Journal 925, no. 2 (February 1, 2022): 220. http://dx.doi.org/10.3847/1538-4357/ac2b33.

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Abstract We present the discovery of the fading radio transient FIRST J153350.8+272729. The source had a maximum observed 5 GHz radio luminosity of 8 × 1039 erg s−1 in 1986, but by 2019 had faded by a factor of nearly 400. It is located at the center of a galaxy (SDSS J153350.89+272729) at 147 Mpc, which shows weak Type II Seyfert activity. We show that a tidal disruption event (TDE) is the preferred scenario for FIRST J153350.8+272729, although it could plausibly be interpreted as the afterglow of a long-duration γ-ray burst. This is only the second TDE candidate to be first discovered at radio wavelengths. Its luminosity fills a gap between the radio afterglows of subrelativistic TDEs in the local universe, and relativistic TDEs at high redshifts. The unusual properties of FIRST J153350.8+272729 (ongoing nuclear activity in the host galaxy, high radio luminosity) motivate more extensive TDE searches in untargeted radio surveys.

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Gangadhara, R. T., and V. Krishan. "Absorption of Electromagnetic Waves in Astrophysical Plasmas." Symposium - International Astronomical Union 142 (1990): 519–20. http://dx.doi.org/10.1017/s0074180900088562.

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We study Parametric Decay Instabilities(PDI) using the kinetic description, in the homogeneous and unmagnetized plasmas. These instabilities cause anomalous absorption of the incident electromagnetic (e.m)radiation. The maximum plasma temperatures reached are functions of luminosity of the non-thermal radio radiation and the plasma parameters.

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Lan, Guang-Xuan, Hou-Dun Zeng, Jun-Jie Wei, and Xue-Feng Wu. "The luminosity function and formation rate of a complete sample of long gamma-ray bursts." Monthly Notices of the Royal Astronomical Society 488, no. 4 (July 25, 2019): 4607–13. http://dx.doi.org/10.1093/mnras/stz2011.

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ABSTRACT We study the luminosity function and formation rate of long gamma-ray bursts (GRBs) by using a maximum likelihood method. This is the first time this method is applied to a well-defined sample of GRBs that is complete in redshift. The sample is composed of 99 bursts detected by the Swift satellite, 81 of them with measured redshift and luminosity for a completeness level of $82\, {\rm per\, cent}$. We confirm that a strong redshift evolution in luminosity (with an evolution index of $\delta =2.22^{+0.32}_{-0.31}$) or in density ($\delta =1.92^{+0.20}_{-0.21}$) is needed in order to reproduce the observations well. But since the predicted redshift and luminosity distributions in the two scenarios are very similar, it is difficult to distinguish between these two kinds of evolutions only on the basis of the current sample. Furthermore, we also consider an empirical density case in which the GRB rate density is directly described as a broken power-law function and the luminosity function is taken to be non-evolving. In this case, we find that the GRB formation rate rises like $(1+z)^{3.85^{+0.48}_{-0.45}}$ for $z\lesssim 2$ and is proportional to $(1+z)^{-1.07^{+0.98}_{-1.12}}$ for $z\gtrsim 2$. The local GRB rate is $1.49^{+0.63}_{-0.64}$ Gpc−3 yr−1. The GRB rate may be consistent with the cosmic star formation rate (SFR) at $z\lesssim 2$, but shows an enhancement compared to the SFR at $z\gtrsim 2$.

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Loveday, J., P. Norberg, I. K. Baldry, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, S. P. Driver, L. S. Kelvin, and S. Phillipps. "Galaxy and Mass Assembly (GAMA): maximum-likelihood determination of the luminosity function and its evolution." Monthly Notices of the Royal Astronomical Society 451, no. 2 (June 5, 2015): 1540–52. http://dx.doi.org/10.1093/mnras/stv1013.

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Guseva, N. G., T. X. Thuan, and Y. I. Izotov. "Decade-long time-monitoring of candidate luminous blue variable stars in the two very metal-deficient star-forming galaxies DDO 68 and PHL 293B." Monthly Notices of the Royal Astronomical Society 512, no. 3 (March 25, 2022): 4298–307. http://dx.doi.org/10.1093/mnras/stac820.

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ABSTRACT We have studied the spectral time variations of candidate luminous blue variable (cLBV) stars in two low-metallicity star-forming galaxies, DDO 68 and PHL 293B. The LBV in DDO 68, located in H ii region #3, shows an outburst, with an increase of more than 1000 times in H α luminosity during the period 2008–2010. The broad emission of the H i and He i lines display a P Cygni profile, with a relatively constant terminal velocity of ∼800 km s−1, reaching a maximum luminosity L(H α) of ∼2 × 1038 erg s−1, with a full width at half-maximum (FWHM) of ∼1000–1200 km s−1. On the other hand, since the discovery of a cLBV in 2001 in PHL 293B, the fluxes of the broad components and the broad-to-narrow flux ratios of the H i and He i emission lines in this galaxy have remained nearly constant over 16 yr, with small variations. The luminosity of the broad H α component varies between ∼2 × 1038 erg s−1 and ∼1039 erg s−1, with the FWHM varying in the range ∼500–1500 km s−1. Unusually persistent P Cygni features are clearly visible until the end of 2020 despite a decrease of the broad-to-narrow flux ratio in the most recent years. A terminal velocity of ∼800 km s−1 is measured from the P Cygni profile, similar to the one in DDO 68, although the latter is 3.7 more metal-deficient than PHL 293B. The relative constancy of the broad H α luminosity in PHL 293B suggests that it is due to a long-lived stellar transient of type LBV/SN IIn.

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Ögelman, H., J. Krautter, and K. Beuermann. "Exosat Observations of X-Rays from Classical Novae during Outburst Stage." International Astronomical Union Colloquium 93 (1987): 279. http://dx.doi.org/10.1017/s0252921100104981.

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AbstractThe initial discovery of soft X-rays from Nova Muscae 1983 was followed by eight additional observations of the three brightest novae whose outburst stage coincided with the lifetime of EXOSAT satellite; namely three more observations of Nova Muscae 1983, three observations of Nova Vulpeculae 1984 # 1 (PW Vul), and two observations of Nova Vulpeculae 1984 # 2. Through these observations we sampled the soft X-ray light curve of classical novae from optical maximum to ~ 900 days after. The observations seem best explained by the constant bolometric luminosity model of a hot white dwarf remnant. Although the measurements suffer from limited statistics, very broad energy bandpass, and incomplete sampling of any single nova, their constraints on the theories of nova outburst are significant. One constraint is that the lifetime of the white dwarf remnant in Nova Muscae 1983 is ~ 2 to 3 years, which leads to the conclusion that the burned envelope mass Mburn should be of the order of . The second constraint is that the maximum temperature, of the white dwarf remnant should approximately be within 200 000 K to 400 000 K. We estimate that a white dwarf remnant evolving like the central star of a planetary nebula, with core mass of 0.8 to 0.9 M⊙, core luminosity of ~ 2 × 104L⊙, and envelope mass of 10−6M⊙, can explain the general characteristics of the X-ray measurements for Nova Muscae 1983. In order to have ≥ 1.1 M⊙ core mass, estimated from the early observations of bolometric luminosity in the UV to infrared range, a wind with Ṁ ≤ 5 × 10−7M⊙yr−1 appears to be necessary. The few observations of Nova Vulpeculae 1984 # 1 and Nova Vulpeculae 1984 # 2 , during the first year after outburst, give a risetime and intensity that is consistent with a constant bolometric luminosity model.

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Verheijen, Marc, and Brent Tully. "A dichotomy between HSB and LSB galaxies." International Astronomical Union Colloquium 171 (1999): 92–101. http://dx.doi.org/10.1017/s0252921100054166.

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AbstractA complete sample of spiral galaxies in the Ursa Major cluster is imaged at various optical wavelengths and in the Near-Infrared K′-band. HI rotation curves were obtained for all gas rich systems. The Near-Infrared surface brightness distribution of disk galaxies turns out to be bimodal; galaxies avoid a domain around mag/arcsec2. This bimodality is particularly striking when only the more isolated, non-interacting systems are considered. The Luminosity Function of the HSB family of galaxies is truncated well above the completion limit while the Luminosity Function of the LSB family is still sharply rising at our limiting magnitude. Near-Infrared mass-to-light ratios suggest that HSB galaxies are close to a kinematic maximum-disk situation while LSB galaxies are dark matter dominated at all radii. Assuming equal Near-Infrared mass-to-light ratios for both HSB and LSB systems, we find that the gap in the surface brightness distribution corresponds to a situation in which the baryonic mass is marginally self-gravitating. We finally conclude that the luminosity-line width relation is a fundamental correlation between the amount and distribution of dark matter mass and the total luminosity, regardless of how the luminous mass is distributed within the dark mater halo.

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Chauhan, J., J. C. A. Miller-Jones, G. E. Anderson, W. Raja, A. Bahramian, A. Hotan, B. Indermuehle, et al. "An H i absorption distance to the black hole candidate X-ray binary MAXI J1535–571." Monthly Notices of the Royal Astronomical Society: Letters 488, no. 1 (July 15, 2019): L129—L133. http://dx.doi.org/10.1093/mnrasl/slz113.

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ABSTRACT With the Australian Square Kilometre Array Pathfinder (ASKAP) we monitored the black hole candidate X-ray binary MAXI J1535–571 over seven epochs from 2017 September 21 to October 2. Using ASKAP observations, we studied the H i absorption spectrum from gas clouds along the line of sight and thereby constrained the distance to the source. The maximum negative radial velocities measured from the H i absorption spectra for MAXI J1535–571 and an extragalactic source in the same field of view are −69 ± 4 and −89 ± 4 km s−1, respectively. This rules out the far kinematic distance ($9.3^{+0.5}_{-0.6}$ kpc), giving a most likely distance of $4.1^{+0.6}_{-0.5}$ kpc, with a strong upper limit of the tangent point at $6.7^{+0.1}_{-0.2}$ kpc. At our preferred distance, the peak unabsorbed luminosity of MAXI J1535–571 was >78 per cent of the Eddington luminosity, and shows that the soft-to-hard spectral state transition occurred at the very low luminosity of (1.2–3.4) × 10−5 times the Eddington luminosity. Finally, this study highlights the capabilities of new wide-field radio telescopes to probe Galactic transient outbursts, by allowing us to observe both a target source and a background comparison source in a single telescope pointing.

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Courteau, Stéphane, Michael McDonald, and Lawrence M. Widrow. "The Vc − σ0 relation of galaxies." Proceedings of the International Astronomical Union 3, S245 (July 2007): 227–30. http://dx.doi.org/10.1017/s1743921308017717.

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AbstractCourteau et al. (2007a) reported on the dependence of the ratio of a galaxy's maximum circular velocity, Vc, to its central velocity dispersion, σ0, on morphology, or equivalently total light concentration. This Vc − σ0–concentration relation, which involves details about the local and global galaxy physics, poses a fundamental challenge for galaxy structure models. Furthermore, not only must these models reproduce the Vc − σ0 relation and its various dependences, they must simultaneously match other fundamental scaling relations such as the velocity-size-luminosity and color-luminosity relations. We focus here on the interpretation of parameters that enter the Vc − σ0 relation to enable proper data-model comparisons and follow-up studies by galaxy modelers and observers.

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Journal articles on the topic 'Maximum Luminosity'

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