Browsing by Subject "galaxies: starburst"
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Item Are Dusty Galaxies Blue? Insights On Uv Attenuation From Dust-Selected Galaxies(2014-12) Casey, C. M.; Scoville, N. Z.; Sanders, D. B.; Lee, N.; Cooray, Asantha; Finkelstein, Steven L.; Capak, P.; Conley, A.; De Zotti, G.; Farrah, D.; Fu, H.; Le Floc'h, E.; Ilbert, O.; Ivison, Rob J.; Takeuchi, T. T.; Finkelstein, Steven L.Galaxies' rest-frame ultraviolet (UV) properties are often used to directly infer the degree to which dust obscuration affects the measurement of star formation rates (SFRs). While much recent work has focused on calibrating dust attenuation in galaxies selected at rest-frame ultraviolet wavelengths, locally and at high-z, here we investigate attenuation in dusty, star forming galaxies (DSFGs) selected at far-infrared wavelengths. By combining multiwavelength coverage across 0.15-500 mu m in the COSMOS field, in particular making use of Herschel imaging, and a rich data set on local galaxies, we find an empirical variation in the relationship between the rest-frame UV slope (beta) and the ratio of infrared-to-ultraviolet emission (L-IR/L-UV = IRX) as a function of infrared luminosity, or total SFR. Both locally and at high-z, galaxies above SFR greater than or similar to 50 M-circle dot yr(-1) deviate from the nominal IRX-beta relation toward bluer colors by a factor proportional to their increasing IR luminosity. We also estimate contamination rates of DSFGs on high-z dropout searches of << 1% at z less than or similar to 4-10, providing independent verification that contamination from very dusty foreground galaxies is low in Lyman-break galaxy searches. Overall, our results are consistent with the physical interpretation that DSFGs, e.g., galaxies with > 50 M-circle dot yr(-1), are dominated at all epochs by short-lived, extreme burst events, producing many young O and B stars that are primarily, yet not entirely, enshrouded in thick dust cocoons. The blue rest-frame UV slopes of DSFGs are inconsistent with the suggestion that most DSFGs at z similar to 2 exhibit steady-Statestar formation in secular disks.Item Evidence For Elevated X-Ray Emission In Local Lyman Break Galaxy Analogs(2013-09) Basu-Zych, Antara R.; Lehmer, Bret D.; Hornschemeier, Ann E.; Goncalves, Thiago S.; Fragos, Tassos; Heckman, Timothy M.; Overzier, Roderik A.; Ptak, Andrew F.; Schiminovich, David; Basu-Zych, Antara R., Bret D. Lehmer, Ann E. Hornschemeier, Thiago S. Gon�alves, Tassos Fragos, Timothy M. Heckman, Roderik A. Overzier, Andrew F. Ptak, and David Schiminovich. "Evidence for elevated x-ray emission in local Lyman break galaxy analogs." The Astrophysical Journal, Vol. 774, No. 2 (Sep., 2013): 152.Our knowledge of how X-ray emission scales with star formation at the earliest times in the universe relies on studies of very distant Lyman break galaxies (LBGs). In this paper, we study the relationship between the 2-10 keV X-ray luminosity (L-X), assumed to originate from X-ray binaries (XRBs), and star formation rate (SFR) in ultraviolet (UV) selected z < 0.1 Lyman break analogs (LBAs). We present Chandra observations for four new Galaxy Evolution Explorer selected LBAs. Including previously studied LBAs, Haro 11 and VV 114, we find that LBAs demonstrate L-X/SFR ratios that are elevated by similar to 1.5 sigma compared to local galaxies, similar to the ratios found for stacked LBGs in the early universe (z > 2). Unlike some of the composite LBAs studied previously, we show that these LBAs are unlikely to harbor active galactic nuclei, based on their optical and X-ray spectra and the spatial distribution of the X-rays in three spatially extended cases. Instead, we expect that high-mass X-ray binaries (HMXBs) dominate the X-ray emission in these galaxies, based on their high specific SFRs (sSFRs SFR/M-star >= 10(-9) yr(-1)), which suggest the prevalence of young stellar populations. Since both UV-selected populations (LBGs and LBAs) have lower dust attenuations and metallicities compared to similar samples of more typical local galaxies, we investigate the effects of dust extinction and metallicity on the L-X/SFR for the broader population of galaxies with high sSFRs (>10(-10) yr(-1)). The estimated dust extinctions (corresponding to column densities of N-H < 10(22) cm(-2)) are expected to have insignificant effects on observed L-X/SFR ratio for the majority of galaxy samples. We find that the observed relationship between L-X/SFR and metallicity appears consistent with theoretical expectations from XRB population synthesis models. Therefore, we conclude that lower metallicities, related to more luminous HMXBs such as ultraluminous X-ray sources, drive the elevated L-X/SFR observed in our sample of z < 0.1 LBAs. The relatively metal-poor, active mode of star formation in LBAs and distant z > 2 LBGs may yield higher total HMXB luminosity than found in typical galaxies in the local universe.Item Extreme Gas Fractions in Clumpy, Turbulent Disk Galaxies at Z Similar To 0.1(2014-08) Fisher, David B.; Glazebrook, Karl; Bolatto, Alberto; Obreschkow, Danail; Cooper, Erin Mentuch; Wisnioski, Emily; Bassett, Robert; Abraham, Roberto G.; Damjanov, Ivana; Green, Andy; McGregor, Peter; Cooper, Erin MentuchIn this Letter, we report the discovery of CO fluxes, suggesting very high gas fractions in three disk galaxies seen in the nearby universe (z similar to 0.1). These galaxies were investigated as part of the DYnamics of Newly Assembled Massive Objects (DYNAMO) survey. High-resolution Hubble Space Telescope imaging of these objects reveals the presence of large star forming clumps in the bodies of the galaxies, while spatially resolved spectroscopy of redshifted II alpha reveals the presence of high dispersion rotating disks. The internal dynamical state of these galaxies resembles that of disk systems seen at much higher redshifts (1 < z < 3). Using CO(1-0) observations made with the Plateau de Bure Interferometer, we find gas fractions of 20%-30% and depletion times of t(dep) similar to 0.5 Gyr (assuming aMilky-Way-like alpha(CO)). These properties are unlike those expected for low-redshift galaxies of comparable specific star Formation rate, but they are normal for their high-z counterparts. DYNAMO galaxies break the degeneracy between gas fraction and redshift, and we show that the depletion time per specific star Formation rate for galaxies is closely tied to gas fraction, independent of redshift. We also show that the gas dynamics of two of our local targets corresponds to those expected from unstable disks, again resembling the dynamics of high-z disks. These results provide evidence that DYNAMO galaxies are local analogs to the clumpy, turbulent disks, which are often found at high redshift.Item Ionized Gas Kinematics At High Resolution. II. Discovery Of A Double Infrared Cluster In II Zw 40(2013-04) Beck, Sara; Turner, Jean; Lacy, John; Greathouse, Thomas K.; Lahad, Ohr; Lacy, JohnThe nearby dwarf galaxy II Zw 40 hosts an intense starburst. At the center of the starburst is a bright compact radio and infrared source, thought to be a giant dense H II region containing approximate to 14,000 O stars. Radio continuum images suggest that the compact source is actually a collection of several smaller emission regions. We accordingly use the kinematics of the ionized gas to probe the structure of the radio-infrared emission region. With TEXES on the NASA-IRTF we measured the 10.5 mu m [S IV] emission line with effective spectral resolutions, including thermal broadening, of similar to 25 and similar to 3 km s(-1) and spatial resolution similar to 1 ''. The line profile shows two distinct, spatially coextensive, emission features. The stronger feature is at galactic velocity and has FWHM 47 km s(-1). The second feature is similar to 44 km s(-1) redward of the first and has FWHM 32 km s(-1). We argue that these are two giant embedded clusters, and estimate their masses to be approximate to 3 x 10(5) M-circle dot and approximate to 1.5 x 10(5) M-circle dot. The velocity shift is unexpectedly large for such a small spatial offset. We suggest that it may arise in a previously undetected kinematic feature remaining from the violent merger that formed the galaxy.Item Ionized Gas Kinematics At High Resolution. IV. Star Formation And A Rotating Core In The Medusa (NGC 4194)(2014-05) Beck, Sara C.; Lacy, John; Turner, Jean; Greathouse, Thomas K.; Neff, Susan; Lacy, JohnNGC 4194 is a post-merger starburst known as The Medusa for its striking tidal features. We present here a detailed study of the structure and kinematics of ionized gas in the central 0.65 kpc of the Medusa. The data include radio continuum maps with resolution up to 0."18 (35 pc) and a 12.8 mu m [Ne II] data cube with spectral resolution similar to 4 km s(-1): the first high-resolution, extinction-free observations of this remarkable object. The ionized gas has the kinematic signature of a core in solid-body rotation. The starburst has formed a complex of bright compact H II regions, probably excited by deeply embedded super star clusters, but none of these sources is a convincing candidate for a Galactic nucleus. The nuclei of the merger partners that created the Medusa have not yet been identified.Item Keck-I Mosfire Spectroscopy Of Compact Star-Forming Galaxies At Z Greater Than Or Similar To 2: High Velocity Dispersions In Progenitors Of Compact Quiescent Galaxies(2014-11) Barro, Guillermo; Trump, Jonathan R.; Koo, David C.; Dekel, Avishai; Kassin, Susan A.; Kocevski, Dale D.; Faber, Sandra M.; van der Wel, Arjen; Guo, Yicheng; Perez-Gonzalez, Pablo G.; Toloba, Elisa; Fang, Jerome J.; Pacifici, Camilla; Simons, Raymond; Campbell, Randy D.; Ceverino, Daniel; Finkelstein, Steven L.; Goodrich, Bob; Kassis, Marc; Koekemoer, Anton M.; Konidaris, Nicholas P.; Livermore, Rachael C.; Lyke, James E.; Mobasher, Bahram; Nayyeri, Hooshang; Peth, Michael; Primack, Joel R.; Rizzi, Luca; Somerville, Rachel S.; Wirth, Gregory D.; Zolotov, Adi; Finkelstein, Steven L.; Livermore, Rachael C.We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13 compact star-forming galaxies (SFGs) at redshift 2 <= z <= 2.5 with star formation rates of SFR similar to 100M(circle dot)yr(-1) and masses of log( M/M-circle dot) similar to 10.8. Their high integrated gas velocity dispersions of sigma(int) = 230(-30)(+40)km s(-1), as measured from emission lines of Ha and [O III], and the resultant M-star-sigma(int) relation and M-star-M-dyn all match well to those of compact quiescent galaxies at z similar to 2, as measured from stellar absorption lines. Since log( M-star/M-dyn)= -0.06 +/- 0.2 dex, these compact SFGs appear to be dynamically relaxed and evolved, i.e., depleted in gas and dark matter (<13(-13)(+17)%), and present larger sint than their non-compact SFG counterparts at the same epoch. Without infusion of external gas, depletion timescales are short, less than similar to 300 Myr. This discovery adds another link to our new dynamical chain of evidence that compact SFGs at z greater than or similar to 2 are already losing gas to become the immediate progenitors of compact quiescent galaxies by z similar to 2.Item Less Than 10 Percent Of Star Formation In Z Similar To 0.6 Massive Galaxies Is Triggered By Major Interactions(2009-10) Robaina, Aday R.; Bell, Eric F.; Skelton, Rosalind E.; McIntosh, Daniel H.; Somerville, Rachel S.; Zheng, Xianzhong; Rix, Hans-Walter; Bacon, David; Balogh, Michael; Barazza, Fabio D.; Barden, Marco; Boehm, Asmus; Caldwell, John A. R.; Gallazzi, Anna; Gray, Meghan E.; Haeussler, Boris; Heymans, Catherine; Jahnke, Knud; Jogee, Shardha; van Kampen, Eelco; Lane, Kyle; Meisenheimer, Klaus; Papovich, Casey; Peng, Chien Y.; Sanchez, Sebastian F.; Skibba, Ramin; Taylor, Andy; Wisotzki, Lutz; Wolf, Christian; Jogee, ShardhaBoth observations and simulations show that major tidal interactions or mergers between gas-rich galaxies can lead to intense bursts of star formation. Yet, the average enhancement in star formation rate (SFR) in major mergers and the contribution of such events to the cosmic SFR are not well estimated. Here we use photometric redshifts, stellar masses, and UV SFRs from COMBO-17, 24 mu m SFRs from Spitzer, and morphologies from two deep Hubble Space Telescope (HST) cosmological survey fields (ECDFS/GEMS and A901/STAGES) to study the enhancement in SFR as a function of projected galaxy separation. We apply two-point projected correlation function techniques, which we augment with morphologically selected very close pairs (separation <2 '') and merger remnants from the HST imaging. Our analysis confirms that the most intensely star-forming systems are indeed interacting or merging. Yet, for massive (M(*) >= 10(10) M(circle dot)) star-forming galaxies at 0.4 < z < 0.8, we find that the SFRs of galaxies undergoing a major interaction (mass ratios <= 1:4 and separations <= 40 kpc) are only 1.80 +/- 0.30 times higher than the SFRs of non-interacting galaxies when averaged over all interactions and all stages of the interaction, in good agreement with other observational works. Our results also agree with hydrodynamical simulations of galaxy interactions, which produce some mergers with large bursts of star formation on similar to 100 Myr timescales, but only a modest SFR enhancement when averaged over the entire merger timescale. We demonstrate that these results imply that only less than or similar to 10% of star formation at 0.4 <= z <= 0.8 is triggered directly by major mergers and interactions; these events are not important factors in the build-up of stellar mass since z = 1.Item A Massive, Distant Proto-Cluster at Z=2.47 Caught in a Phase of Rapid Formation?(2015-08) Casey, C. M.; Cooray, A.; Capak, P.; Fu, H.; Kovac, K.; Lilly, S.; Sanders, D. B.; Scoville, N. Z.; Treister, E.; Casey, C. M.Numerical simulations of cosmological structure Formation show that the universe's most massive clusters, and the galaxies living in those clusters, assemble rapidly at early times (2.5 < z < 4). While more than 20 proto-clusters have been observed at z greater than or similar to 2 based on associations of 5-40 galaxies around rare sources, the observational evidence for rapid cluster Formation is weak. Here we report observations of an asymmetric filamentary structure at z = 2.47 containing 7 starbursting, submillimeter-luminous galaxies and 5 additional active galactic nuclei (AGNs) within a comoving volume of 15,000 Mpc(3). As the expected lifetime of both the luminous AGN and starburst phase of a galaxy is similar to 100 Myr, we conclude that these sources were likely triggered in rapid succession by environmental factors or, alternatively, the duration of these cosmologically rare phenomena is much longer than prior direct measurements suggest. The stellar mass already built up in the structure is similar to 10(12) M-circle dot and we estimate that the cluster mass will exceed that of the Coma supercluster at z similar to 0. The filamentary structure is in line with hierarchical growth simulations that predict that the peak of cluster activity occurs rapidly at z > 2.Item New Constraints On Dust Emission And UV Attenuation Of Z=6.5-7.5 Galaxies From Millimeter Observations(2015-02) Schaerer, D.; Boone, F.; Zamojski, M.; Staguhn, J.; Dessauges-Zavadsky, M.; Finkelstein, S.; Combes, F.; Finkelstein, S.Context. Determining the dust properties and UV attenuation of distant star-forming galaxies is of great interest for our understanding of galaxy formation and cosmic star formation in the early Universe. However, few direct measurements exist so far. Aims. To shed new light on these questions, we have targeted two recently discovered Lyman-break galaxies (LBGs) at z approximate to 6.8 and z = 7.508 to search for dust continuum and [C II] 1158 pm line emission. Methods. The strongly lensed z approximate to 6.8 LBG A1703-zD1 behind the galaxy cluster Abell 1703 and the spectroscopically confirmed z = 7.508 LBG z8-GND-5296 in the GOODS-N field were observed with the Plateau de Bure Interferometer (PdBI) at 1.2 mm. These observations were combined with those of three z > 6.5 Ly alpha emitters (HCM6A, Himiko, and IOK-1), for which deep measurements were recently obtained with the PdBI and ALMA. Results. [C II] is undetected in both galaxies, providing a deep upper limit of L-[C II] < 2.8 x 10(7) L for A1703-zD1, comparable to the nondetections of Himiko and IOK-1 with ALMA. Dust continuum emission from A1703-zD1 and z8-GND-5296 is not detected with an rms of 0.12 and 0.16 mJy/beam. From these nondetections and earlier multiwavelength observations we derive upper limits on their IR luminosity and star formation rate, dust mass, and UV attenuation. Thanks to strong gravitational lensing, the achieved limit for A1703-zDI is similar to those achieved with ALMA, probing below the luminous infrared galaxy (LIRG) regime (L-IR < 8.1 x 10(10) L-circle dot) and very low dust masses (M-d < 1.6 x 10(7) M-circle dot). We find that all five galaxies are compatible with the Calzetti IRX-beta relation, their UV attenuation is compatible with several indirect estimates from other methods (the UV slope, extrapolation of the attenuation measured from the IR/UV ratio at lower redshift, and spectral energy distribution fits), and the dust-to-stellar mass ratio is compatible with that of galaxies from z = 0 to 3. From their stellar mass, the high-z galaxies studied here have an attenuation below the one expected from the mean relation of low-redshift (z less than or similar to 1.5) galaxies. Conclusions. More and deeper (sub-)mm data are clearly needed to directly determine the UV attenuation and dust content of the dominant population of high-z star-forming galaxies and to establish their dependence on stellar mass, redshift, and other properties more firmly.Item NGC 4102: High-Resolution Infrared Observations Of A Nuclear Starburst Ring(2010-10) Beck, Sara C.; Lacy, John H.; Turner, Jean L.; Lacy, John H.The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 mu m line of [Ne II], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 1 ''.5 spatial, and 25 km s(-1) spectral, resolution. Combining near-infrared, radio, and the [Ne II] data shows that the extinction to the starburst is substantial, more than 2 mag at the K band, and that the neon abundance is less than half solar. We find that the star formation in the nuclear region is confined to a rotating ring or disk of 4 ''.3 (similar to 300 pc) diameter, inside the inner Lindblad resonance. This region is an intense concentration of mass, with a dynamical mass similar to 3 x 10(9) M(circle dot), and of star formation. The young stars in the ring produce the [Ne II] flux reported by Spitzer for the entire galaxy. The mysterious blue component of line emission detected in the near-infrared is also seen in [Ne II]; it is not a normal active galactic nucleus outflow.Item Probing The Star Formation History And Initial Mass Function Of The Z Similar To 2.5 Lensed Galaxy Smm J163554.2+661225 With Herschel(2011-12) Finkelstein, Keely D.; Papovich, Casey; Finkelstein, Steven L.; Willmer, Christopher N. A.; Rigby, Jane R.; Rudnick, Gregory; Egami, Eiichi; Rieke, M.; Smith, J. D. T.; Finkelstein, Keely D.; Finkelstein, Steven L.We present the analysis of Herschel Spectral and Photometric Imaging Receiver far-infrared (FIR) observations of the z = 2.515 lensed galaxy SMM J163554.2+661225. Combining new 250, 350, and 500 mu m observations with existing data, we make an improved fit to the FIR spectral energy distribution of this galaxy. We find a total infrared (IR) luminosity of L(8-1000 mu m) = 6.9 +/- 0.6 x 10(11) L-circle dot, a factor of three more precise over previous L-IR estimates for this galaxy, and one of the most accurate measurements for any galaxy at these redshifts. This FIR luminosity implies an unlensed star formation rate (SFR) for this galaxy of 119 +/- 10 M-circle dot yr(-1), which is a factor of 1.9 +/- 0.35 lower than the SFR derived from the nebular Pa alpha emission line (a 2.5 sigma discrepancy). Both SFR indicators assume an identical Salpeter initial mass function (IMF) with slope Gamma = 2.35 over a mass range of 0.1-100 M-circle dot; thus this discrepancy suggests that more ionizing photons may be necessary to account for the higher Pa alpha-derived SFR. We examine a number of scenarios and find that the observations can be explained with a varying star formation history (SFH) due to an increasing SFR, paired with a slight flattening of the IMF. If the SFR is constant in time, then larger changes need to be made to the IMF by either increasing the upper mass cutoff to similar to 200 M-circle dot, or a flattening of the IMF slope to 1.9 +/- 0.15, or a combination of the two. These scenarios result in up to double the number of stars with masses above 20 M-circle dot, which produce the requisite increase in ionizing photons over a Salpeter IMF with a constant SFH.Item S IV In The NGC 5253 Supernebula: Ionized Gas Kinematics At High Resolution(2012-08) Beck, Sara C.; Lacy, John H.; Turner, Jean L.; Kruger, Andrew; Richter, Matt; Crosthwaite, Lucian P.; Lacy, John H.The nearby dwarf starburst galaxy NGC 5253 hosts a deeply embedded radio-infrared supernebula excited by thousands of O stars. We have observed this source in the 10.5 mu m line of S+3 at 3.8 km s(-1) spectral and 1 ''.4 spatial resolution, using the high-resolution spectrometer TEXES on the IRTF. The line profile cannot be fit well by a single Gaussian. The best simple fit describes the gas with two Gaussians, one near the galactic velocity with FWHM 33.6 km s(-1) and another of similar strength and FWHM 94 km s(-1) centered similar to 20 km s(-1) to the blue. This suggests a model for the supernebula in which gas flows toward us out of the molecular cloud, as in a "blister" or "champagne flow" or in the H II regions modelled by Zhu.Item Spectral Energy Distribution Fitting Of HETDEX Pilot Survey Ly Alpha Emitters In Cosmos And GOODS-N(2014-05) Hagen, Alex; Ciardullo, Robin; Gronwall, Caryl; Acquaviva, Viviana; Bridge, Joanna; Zeimann, Gregory R.; Blanc, Guillermo A.; Bond, Nicholas A.; Finkelstein, Steven L.; Song, Mimi; Gawiser, Eric; Fox, Derek B.; Gebhardt, Henry; Malz, A. I.; Schneider, Donald P.; Drory, Niv; Gebhardt, Karl; Hill, Gary J.; Drory, Niv; Gebhardt, Karl; Hill, Gary J.We use broadband photometry extending from the rest-frame UV to the near-IR to fit the individual spectral energy distributions of 63 bright (L(Ly alpha) > 10(43) erg s(-1)) Ly alpha emitting galaxies (LAEs) in the redshift range 1.9 < z < 3.6. We find that these LAEs are quite heterogeneous, with stellar masses that span over three orders of magnitude, from 7.5 < log M/M-circle dot < 10.5. Moreover, although most LAEs have small amounts of extinction, some high-mass objects have stellar reddenings as large as E(B - V) similar to 0.4. Interestingly, in dusty objects the optical depths for Ly alpha and the UV continuum are always similar, indicating that Ly alpha photons are not undergoing many scatters before escaping their galaxy. In contrast, the ratio of optical depths in low-reddening systems can vary widely, illustrating the diverse nature of the systems. Finally, we show that in the star-formation-rate-log-mass diagram, our LAEs fall above the "main-sequence" defined by z similar to 3 continuum selected star-forming galaxies. In this respect, they are similar to submillimeter-selected galaxies, although most LAEs have much lower mass.Item A Spitzer High-Resolution Mid-Infrared Spectral Atlas of Starburst Galaxies(2009-10) Bernard-Salas, J.; Spoon, H. W. W.; Charmandaris, V.; Lebouteiller, V.; Farrah, D.; Devost, D.; Brandl, B. R.; Wu, Y. L.; Armus, L.; Hao, L.; Sloan, G. C.; Weedman, D.; Houck, J. R.; Hao, L.We present an atlas of Spitzer/IRS high-resolution (R similar to 600) 10-37 mu m spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation [Ne v] line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4 mu m), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2 mu m, and a previously unreported emission feature at 10.75 mu m. An unidentified absorption feature at 13.7 mu m is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the Hi 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.