Evolution of Galactic Outflows at z∼0z\sim0-22 Revealed with SDSS, DEEP2, and Keck spectra

We conduct a systematic study of galactic outflows in star-forming galaxies at $z\sim0$-$2$ based on the absorption lines of optical spectra taken from SDSS DR7, DEEP2 DR4, and Keck Erb et al. We carefully make stacked spectra of homogeneous galaxy samples with similar stellar mass distributions at $z\sim0$-$2$, and perform the multi-component fitting of model absorption lines and stellar continua to the stacked spectra. We obtain the maximum (v_\rm{max}) and central (v_\rm{out}) outflow velocities, and estimate the mass loading factors ($\eta$), a ratio of the mass outflow rate to the star formation rate (SFR). Investigating the redshift evolution of the outflow velocities measured with the absorption lines whose depths and ionization energies are similar (Na I D and Mg I at $z\sim0$-$1$; Mg II and C II at $z\sim1$-$2$), we identify, for the first time, that the average value of v_\rm{max} (v_\rm{out}) significantly increases by 0.05-0.3 dex from $z\sim0$ to $2$ at a given SFR. Moreover, we find that the value of $\eta$ increases from $z\sim0$ to $2$ by $\eta \propto (1 + z)^{1.2\pm0.3}$ at a given halo circular velocity v_\rm{cir} , albeit with a potential systematics caused by model parameter choices. The redshift evolution of v_\rm{max} (v_\rm{out}) and $\eta$ is consistent with the galaxy-size evolution and the local velocity-SFR surface density relation, and explained by high-gas fractions in high-redshift massive galaxies, which is supported by recent radio observations. We obtain a scaling relation of \eta \propto v_\rm{cir}^a for $a = -0.2 \pm 1.1$ in our $z\sim0$ galaxies that agrees with the momentum-driven outflow model ($a = -1$) within the uncertainty.Comment: 13 pages, 10 figures, ApJ in pres

Identifying and Quantifying Recurrent Novae Masquerading as Classical Novae

Recurrent novae (RNe) are cataclysmic variables with two or more nova eruptions within a century. Classical novae (CNe) are similar systems with only one such eruption. Many of the so-called 'CNe' are actually RNe for which only one eruption has been discovered. Since RNe are candidate Type Ia supernova progenitors, it is important to know whether there are enough in our galaxy to provide the supernova rate, and therefore to know how many RNe are masquerading as CNe. To quantify this, we collected all available information on the light curves and spectra of a Galactic, time-limited sample of 237 CNe and the 10 known RNe, as well as exhaustive discovery efficiency records. We recognize RNe as having (a) outburst amplitude smaller than 14.5 - 4.5 * log(t_3), (b) orbital period >0.6 days, (c) infrared colors of J-H > 0.7 mag and H-K > 0.1 mag, (d) FWHM of H-alpha > 2000 km/s, (e) high excitation lines, such as Fe X or He II near peak, (f) eruption light curves with a plateau, and (g) white dwarf mass greater than 1.2 M_solar. Using these criteria, we identify V1721 Aql, DE Cir, CP Cru, KT Eri, V838 Her, V2672 Oph, V4160 Sgr, V4643 Sgr, V4739 Sgr, and V477 Sct as strong RN candidates. We evaluate the RN fraction amongst the known CNe using three methods to get 24% +/- 4%, 12% +/- 3%, and 35% +/- 3%. With roughly a quarter of the 394 known Galactic novae actually being RNe, there should be approximately a hundred such systems masquerading as CNe.Comment: 3 figures, 7 tables, accepted for publication in Ap

Insurance—Fidelity Bonds Held Continuing Contract—Recovery Denied Beyond Face Value

Columbia Hospital for Women and Lying-In Asylum v. United States Fidelity and Guaranty Company, 188 F2d 654 (D. C. Cir. 1951)

Insurance—Fidelity Bonds Held Continuing Contract—Recovery Denied Beyond Face Value

Columbia Hospital for Women and Lying-In Asylum v. United States Fidelity and Guaranty Company, 188 F2d 654 (D. C. Cir. 1951)

Constitutional Law—Search and Seizure—Evidence Obtained During Search Suppressed

Jeffers v. United States, 187 F. 2d 498 (D. C. Cir. 1950); aff\u27d. __ U. S. __, 20 U. S. L. Week 4011 (Nov. 13, 1951)

Experimental Evaluation of Book Drawing Algorithms

A $k$-page book drawing of a graph $G=(V,E)$ consists of a linear ordering of its vertices along a spine and an assignment of each edge to one of the $k$ pages, which are half-planes bounded by the spine. In a book drawing, two edges cross if and only if they are assigned to the same page and their vertices alternate along the spine. Crossing minimization in a $k$-page book drawing is NP-hard, yet book drawings have multiple applications in visualization and beyond. Therefore several heuristic book drawing algorithms exist, but there is no broader comparative study on their relative performance. In this paper, we propose a comprehensive benchmark set of challenging graph classes for book drawing algorithms and provide an extensive experimental study of the performance of existing book drawing algorithms.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017