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Showing 1-9 of about 9 results.
Extended X-Ray Emission in Compton Thick AGN with Deep Chandra ObservationsJones, Mackenzie L.Parker, KieranFabbiano, G.Elvis, MartinMaksym, W. P.Paggi, A.Ma, JingzheKarovska, M.Siemiginowska, AnetaWang, JunfengDOI: info:10.3847/1538-4357/abe128v. 91019
Jones, Mackenzie L., Parker, Kieran, Fabbiano, G., Elvis, Martin, Maksym, W. P., Paggi, A., Ma, Jingzhe, Karovska, M., Siemiginowska, Aneta, and Wang, Junfeng. 2021. "Extended X-Ray Emission in Compton Thick AGN with Deep Chandra Observations." The Astrophysical Journal 910:19.
ID: 159608
Type: article
Authors: Jones, Mackenzie L.; Parker, Kieran; Fabbiano, G.; Elvis, Martin; Maksym, W. P.; Paggi, A.; Ma, Jingzhe; Karovska, M.; Siemiginowska, Aneta; Wang, Junfeng
Abstract: We present the spatial analysis of five Compton thick (CT) active galactic nuclei (AGNs), including MKN 573, NGC 1386, NGC 3393, NGC 5643, and NGC 7212, for which high-resolution Chandra observations are available. For each source, we find hard X-ray emission (>3 keV) extending to ∼kiloparsec scales along the ionization cone, and for some sources, in the cross-cone region. This collection represents the first, high-signal sample of CT AGN with extended hard X-ray emission for which we can begin to build a more complete picture of this new population of AGN. We investigate the energy dependence of the extended X-ray emission, including possible dependencies on host galaxy and AGN properties, and find a correlation between the excess emission and obscuration, suggesting a connection between the nuclear obscuring material and the galactic molecular clouds. Furthermore, we find that the soft X-ray emission extends farther than the hard X-rays along the ionization cone, which may be explained by a galactocentric radial dependence on the density of molecular clouds due to the orientation of the ionization cone with respect to the galactic disk. These results are consistent with other CT AGN with observed extended hard X-ray emission (e.g., ESO 428-G014 and the Ma et al. CT AGN sample), further demonstrating the ubiquity of extended hard X-ray emission in CT AGN.
Spatially Resolved BPT Mapping of Nearby Seyfert 2 GalaxiesMa, JingzheMaksym, W. PeterFabbiano, G.Elvis, MartinStorchi-Bergmann, ThaisaKarovska, MargaritaWang, JunfengTravascio, AndreaDOI: info:10.3847/1538-4357/abcfc1v. 908155
Ma, Jingzhe, Maksym, W. Peter, Fabbiano, G., Elvis, Martin, Storchi-Bergmann, Thaisa, Karovska, Margarita, Wang, Junfeng, and Travascio, Andrea. 2021. "Spatially Resolved BPT Mapping of Nearby Seyfert 2 Galaxies." The Astrophysical Journal 908:155.
ID: 159625
Type: article
Authors: Ma, Jingzhe; Maksym, W. Peter; Fabbiano, G.; Elvis, Martin; Storchi-Bergmann, Thaisa; Karovska, Margarita; Wang, Junfeng; Travascio, Andrea
Abstract: We present spatially resolved Baldwin-Phillips-Terlevich (BPT) mapping of the extended narrow-line regions (ENLRs) of seven nearby Seyfert 2 galaxies, using Hubble Space Telescope narrowband filter imaging. We construct the BPT diagrams using ≤0"1 resolution emission line images of [O III] λ5007, Hα, [S II] λλ6717, 6731, and Hβ. By mapping these diagnostic lines according to the BPT classification, we dissect the ENLR into Seyfert, low-ionization nuclear emission-line (LINER), and star-forming regions. The nucleus and ionization cones are dominated by Seyfert-type emission, which can be interpreted as predominantly photoionization by the active galactic nucleus (AGN). The Seyfert nucleus and ionization cones transition to and are surrounded by a LINER cocoon, extending up to ∼250 pc in thickness. The ubiquity of the LINER cocoon in Seyfert 2 galaxies suggests that the circumnuclear regions are not necessarily Seyfert-type, and LINER activity plays an important role in Seyfert 2 galaxies. We demonstrate that spatially resolved diagnostics are crucial to understanding the excitation mechanisms in different regions and the AGN-host galaxy interactions.
Is Extended Hard X-Ray Emission Ubiquitous in Compton-thick AGN?Ma, JingzheElvis, MartinFabbiano, GiuseppinaBaloković, MislavMaksym, W. PeterJones, Mackenzie L.Risaliti, GuidoDOI: info:10.3847/1538-4357/abacbev. 900164
Ma, Jingzhe, Elvis, Martin, Fabbiano, Giuseppina, Baloković, Mislav, Maksym, W. Peter, Jones, Mackenzie L., and Risaliti, Guido. 2020. "Is Extended Hard X-Ray Emission Ubiquitous in Compton-thick AGN?." The Astrophysical Journal 900:164.
ID: 157684
Type: article
Authors: Ma, Jingzhe; Elvis, Martin; Fabbiano, Giuseppina; Baloković, Mislav; Maksym, W. Peter; Jones, Mackenzie L.; Risaliti, Guido
Abstract: The recent Chandra discovery of extended ∼kiloparsec-scale hard (>3 keV) X-ray emission in nearby Compton-thick (CT) active galactic nuclei (AGN) opens a new window to improving AGN torus modeling and investigating how the central supermassive black hole interacts with and impacts the host galaxy. Since there are only a handful of detections so far, we need to establish a statistical sample to determine the ubiquity of the extended hard X-ray emission in CT AGN and quantify the amount and extent of this component. In this paper, we present the spatial analysis results of a pilot Chandra imaging survey of seven nearby ( $0.006\lt z\lt 0.013$ ) CT AGN selected from the Swift-BAT spectroscopic AGN survey. We find that five out of the seven CT AGN show extended emission in the 3-7 keV band detected at >3σ above the Chandra point-spread function (PSF), with ∼12%-22% of the total emission in the extended components. ESO 137-G034 and NGC 3281 display biconical ionization structures with extended hard X-ray emission reaching kiloparsec scales (∼1.9 and 3.5 kpc in diameter). The other three show extended hard X-ray emission above the PSF out to at least ∼360 pc in radius. We find a trend that a minimum 3-7 keV count rate of 0.01 counts s-1 and total excess fraction >20% are required to detect a prominent extended hard X-ray component. Given that this extended hard X-ray component appears to be relatively common in this uniformly selected CT AGN sample, we further discuss the implications for torus modeling and AGN feedback.
Infrared Contributions of X-Ray Selected Active Galactic Nuclei in Dusty Star-forming GalaxiesBrown, AriannaNayyeri, HooshangCooray, AsanthaMa, JingzheHickox, Ryan C.Azadi, MojeganDOI: info:10.3847/1538-4357/aaf73bv. 87187
Brown, Arianna, Nayyeri, Hooshang, Cooray, Asantha, Ma, Jingzhe, Hickox, Ryan C., and Azadi, Mojegan. 2019. "Infrared Contributions of X-Ray Selected Active Galactic Nuclei in Dusty Star-forming Galaxies." The Astrophysical Journal 871:87.
ID: 150437
Type: article
Authors: Brown, Arianna; Nayyeri, Hooshang; Cooray, Asantha; Ma, Jingzhe; Hickox, Ryan C.; Azadi, Mojegan
Abstract: We investigate the infrared (IR) contribution from supermassive black hole activity versus host galaxy emission in the mid- to far-IR spectrum for a large sample of X-ray bright active galactic nuclei (AGN) residing in dusty, star-forming host galaxies. We select 703 AGN with {L}{{X}}={10}42{--}{10}46 erg s‑1 at 0.1 at 0.1 at 0.1 X in bins of star-forming activity for AGN at low redshifts. We estimate an average dust covering factor (CF) of 33% based on IR SEDs and bolometric AGN luminosity, corresponding to a Type 2 AGN population of roughly a third. We also see a population of AGN that challenge the inclination-based unification model with individual dust CFs that contradict the nuclear obscuration expected from observed X-ray hardness ratios. We see no strong connection between AGN fractions in the IR and corresponding total IR, 24 μm, or X-ray luminosities. The average rest-frame AGN contribution as a function of IR wavelength shows significant (∼80%) contributions in the mid-IR that trail off at λ > 30 μm. Additionally, we provide a relation between observed L X and pure AGN IR output for high-z AGN, allowing future studies to estimate AGN IR contribution using only observed X-ray flux density estimates.
Source Structure and Molecular Gas Properties from High-resolution CO Imaging of SPT-selected Dusty Star-forming GalaxiesDong, ChenxingSpilker, Justin S.Gonzalez, Anthony H.Apostolovski, YordankaAravena, ManuelBéthermin, MatthieuChapman, Scott C.Chen, Chian-ChouHayward, Christopher C.Hezaveh, Yashar D.Litke, Katrina C.Ma, JingzheMarrone, Daniel P.Morningstar, Warren R.Phadke, Kedar A.Reuter, Cassie A.Sreevani, JarugulaStark, Antony A.Vieira, Joaquin D.Weiß, AxelDOI: info:10.3847/1538-4357/ab02fev. 87350
Dong, Chenxing, Spilker, Justin S., Gonzalez, Anthony H., Apostolovski, Yordanka, Aravena, Manuel, Béthermin, Matthieu, Chapman, Scott C., Chen, Chian-Chou, Hayward, Christopher C., Hezaveh, Yashar D., Litke, Katrina C., Ma, Jingzhe, Marrone, Daniel P., Morningstar, Warren R., Phadke, Kedar A., Reuter, Cassie A., Sreevani, Jarugula, Stark, Antony A., Vieira, Joaquin D., and Weiß, Axel. 2019. "Source Structure and Molecular Gas Properties from High-resolution CO Imaging of SPT-selected Dusty Star-forming Galaxies." The Astrophysical Journal 873:50.
ID: 155438
Type: article
Authors: Dong, Chenxing; Spilker, Justin S.; Gonzalez, Anthony H.; Apostolovski, Yordanka; Aravena, Manuel; Béthermin, Matthieu; Chapman, Scott C.; Chen, Chian-Chou; Hayward, Christopher C.; Hezaveh, Yashar D.; Litke, Katrina C.; Ma, Jingzhe; Marrone, Daniel P.; Morningstar, Warren R.; Phadke, Kedar A.; Reuter, Cassie A.; Sreevani, Jarugula; Stark, Antony A.; Vieira, Joaquin D.; Weiß, Axel
Abstract: We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of high-J CO lines (J up = 6, 7, 8) and associated dust continuum toward five strongly lensed, dusty, star- forming galaxies at redshift z = 2.7-5.7. These galaxies, discovered in the South Pole Telescope survey, are observed at 0.″2-0.″4 resolution with ALMA. Our high-resolution imaging coupled with the lensing magnification provides a measurement of the structure and kinematics of molecular gas in the background galaxies with spatial resolutions down to kiloparsec scales. We derive visibility-based lens models for each galaxy, accurately reproducing observations of four of the galaxies. Of these four targets, three show clear velocity gradients, of which two are likely rotating disks. We find that the reconstructed region of CO emission is less concentrated than the region emitting dust continuum even for the moderate-excitation CO lines, similar to what has been seen in the literature for lower-excitation transitions. We find that the lensing magnification of a given source can vary by 20%-50% across the line profile, between the continuum and line, and between different CO transitions. We apply Large Velocity Gradient modeling using apparent and intrinsic line ratios between lower-J and high-J CO lines. Ignoring these magnification variations can bias the estimate of physical properties of interstellar medium of the galaxies. The magnitude of the bias varies from galaxy to galaxy and is not necessarily predictable without high-resolution observations.
Spitzer Catalog of Herschel-selected Ultrared Dusty Star-forming GalaxiesMa, JingzheCooray, AsanthaNayyeri, HooshangBrown, AriannaGhotbi, NoahIvison, RobOteo, IvanDuivenvoorden, StevenGreenslade, JoshuaClements, DavidWardlow, JulieBattisti, Andrewda Cunha, ElisabeteAshby, Matthew L. N.Perez-Fournon, IsmaelRiechers, DominikOliver, SebEales, StephenNegrello, MattiaDye, SimonDunne, LorettaOmont, AlainScott, DouglasCox, PierreSerjeant, StephenMaddox, SteveValiante, ElisabettaDOI: info:10.3847/1538-4365/ab4194v. 24430
Ma, Jingzhe, Cooray, Asantha, Nayyeri, Hooshang, Brown, Arianna, Ghotbi, Noah, Ivison, Rob, Oteo, Ivan, Duivenvoorden, Steven, Greenslade, Joshua, Clements, David, Wardlow, Julie, Battisti, Andrew, da Cunha, Elisabete, Ashby, Matthew L. N., Perez-Fournon, Ismael, Riechers, Dominik, Oliver, Seb, Eales, Stephen, Negrello, Mattia, Dye, Simon, Dunne, Loretta, Omont, Alain, Scott, Douglas, Cox, Pierre, Serjeant, Stephen et al. 2019. "Spitzer Catalog of Herschel-selected Ultrared Dusty Star-forming Galaxies." The Astrophysical Journal Supplement Series 244:30.
ID: 154638
Type: article
Authors: Ma, Jingzhe; Cooray, Asantha; Nayyeri, Hooshang; Brown, Arianna; Ghotbi, Noah; Ivison, Rob; Oteo, Ivan; Duivenvoorden, Steven; Greenslade, Joshua; Clements, David; Wardlow, Julie; Battisti, Andrew; da Cunha, Elisabete; Ashby, Matthew L. N.; Perez-Fournon, Ismael; Riechers, Dominik; Oliver, Seb; Eales, Stephen; Negrello, Mattia; Dye, Simon; Dunne, Loretta; Omont, Alain; Scott, Douglas; Cox, Pierre; Serjeant, Stephen; Maddox, Steve; Valiante, Elisabetta
Abstract: The largest Herschel extragalactic surveys, H-ATLAS and HerMES, have selected a sample of "ultrared" dusty star-forming galaxies (DSFGs) with rising SPIRE flux densities (S 500 > S 350 > S 250; the so-called "500 μm risers") as an efficient way for identifying DSFGs at higher redshift (z > 4). In this paper, we present a large Spitzer follow-up program of 300 Herschel ultrared DSFGs. We have obtained high-resolution Atacama Large Millimeter/submillimeter Array, Northern Extended Millimeter Array, and SMA data for 63 of them, which allow us to securely identify the Spitzer/IRAC counterparts and classify them as gravitationally lensed or unlensed. Within the 63 ultrared sources with high-resolution data, ̃65% appear to be unlensed and ̃27% are resolved into multiple components. We focus on analyzing the unlensed sample by directly performing multiwavelength spectral energy distribution modeling to derive their physical properties and compare with the more numerous z ̃ 2 DSFG population. The ultrared sample has a median redshift of 3.3, stellar mass of 3.7 × 1011 M , star formation rate (SFR) of 730 M yr-1, total dust luminosity of 9.0 × 1012 L , dust mass of 2.8 × 109 M , and V-band extinction of 4.0, which are all higher than those of the ALESS DSFGs. Based on the space density, SFR density, and stellar mass density estimates, we conclude that our ultrared sample cannot account for the majority of the star-forming progenitors of the massive, quiescent galaxies found in infrared surveys. Our sample contains the rarer, intrinsically most dusty, luminous, and massive galaxies in the early universe that will help us understand the physical drivers of extreme star formation.
SOFIA/HAWC+ Detection of a Gravitationally Lensed Starburst Galaxy at z = 1.03Ma, JingzheBrown, AriannaCooray, AsanthaNayyeri, HooshangMessias, HugoTimmons, NicholasStaguhn, JohannesTemi, PasqualeDowell, C. DarrenWardlow, JulieFadda, DarioKovacs, AttilaRiechers, DominikOteo, IvanWilson, DerekPerez-Fournon, IsmaelDOI: info:10.3847/1538-4357/aad4a0v. 86460
Ma, Jingzhe, Brown, Arianna, Cooray, Asantha, Nayyeri, Hooshang, Messias, Hugo, Timmons, Nicholas, Staguhn, Johannes, Temi, Pasquale, Dowell, C. Darren, Wardlow, Julie, Fadda, Dario, Kovacs, Attila, Riechers, Dominik, Oteo, Ivan, Wilson, Derek, and Perez-Fournon, Ismael. 2018. "SOFIA/HAWC+ Detection of a Gravitationally Lensed Starburst Galaxy at z = 1.03." The Astrophysical Journal 864:60.
ID: 149175
Type: article
Authors: Ma, Jingzhe; Brown, Arianna; Cooray, Asantha; Nayyeri, Hooshang; Messias, Hugo; Timmons, Nicholas; Staguhn, Johannes; Temi, Pasquale; Dowell, C. Darren; Wardlow, Julie; Fadda, Dario; Kovacs, Attila; Riechers, Dominik; Oteo, Ivan; Wilson, Derek; Perez-Fournon, Ismael
Abstract: We present the detection at 89 μm (observed frame) of the Herschel-selected gravitationally lensed starburst galaxy HATLAS J1429-0028 (also known as G15v2.19) in 15 minutes with the High-resolution Airborne Wideband Camera-plus (HAWC+) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The spectacular lensing system consists of an edge-on foreground disk galaxy at z = 0.22 and a nearly complete Einstein ring of an intrinsic ultra-luminous infrared (IR) galaxy at z = 1.03. Is this high IR luminosity powered by pure star formation (SF) or also an active galactic nucleus (AGN)? Previous nebular line diagnostics indicate that it is star formation dominated. We perform a 27-band multiwavelength spectral energy distribution (SED) modeling including the new SOFIA/HAWC+ data to constrain the fractional AGN contribution to the total IR luminosity. The AGN fraction in the IR turns out to be negligible. In addition, J1429-0028 serves as a testbed for comparing SED results from different models/templates and SED codes (MAGPHYS, SED3FIT, and CIGALE). We stress that star formation history is the dominant source of uncertainty in the derived stellar mass (as high as a factor of ∼10) even in the case of extensive photometric coverage. Furthermore, the detection of a source at z ∼ 1 with SOFIA/HAWC+ demonstrates the potential of utilizing this facility for distant galaxy studies including the decomposition of SF/AGN components, which cannot be accomplished with other current facilities.
SPT0346-52: Negligible AGN Activity in a Compact, Hyper-starburst Galaxy at z = 5.7Ma, JingzheGonzalez, Anthony H.Vieira, J. D.Aravena, M.Ashby, M. L. N.Béthermin, M.Bothwell, M. S.Brandt, W. Breuck, C.Carlstrom, J. E.Chapman, S. C.Gullberg, B.Hezaveh, Y.Litke, K.Malkan, M.Marrone, D. P.McDonald, M.Murphy, E. J.Spilker, J. S.Sreevani, J.Stark, Antony A.Strandet, M.Wang, S. X.DOI: info:10.3847/0004-637X/832/2/114v. 832114
Ma, Jingzhe, Gonzalez, Anthony H., Vieira, J. D., Aravena, M., Ashby, M. L. N., Béthermin, M., Bothwell, M. S., Brandt, W. N., de Breuck, C., Carlstrom, J. E., Chapman, S. C., Gullberg, B., Hezaveh, Y., Litke, K., Malkan, M., Marrone, D. P., McDonald, M., Murphy, E. J., Spilker, J. S., Sreevani, J., Stark, Antony A., Strandet, M., and Wang, S. X. 2016. "SPT0346-52: Negligible AGN Activity in a Compact, Hyper-starburst Galaxy at z = 5.7." The Astrophysical Journal 832:114.
ID: 141969
Type: article
Authors: Ma, Jingzhe; Gonzalez, Anthony H.; Vieira, J. D.; Aravena, M.; Ashby, M. L. N.; Béthermin, M.; Bothwell, M. S.; Brandt, W. N.; de Breuck, C.; Carlstrom, J. E.; Chapman, S. C.; Gullberg, B.; Hezaveh, Y.; Litke, K.; Malkan, M.; Marrone, D. P.; McDonald, M.; Murphy, E. J.; Spilker, J. S.; Sreevani, J.; Stark, Antony A.; Strandet, M.; Wang, S. X.
Abstract: We present Chandra ACIS-S and Australia Telescope Compact Array (ATCA) radio continuum observations of the strongly lensed dusty, star-forming galaxy SPT-S J034640-5204.9 (hereafter SPT0346-52) at z = 5.656. This galaxy has also been observed with ALMA, HST, Spitzer, Herschel, Atacama Pathfinder EXperiment, and the Very Large Telescope. Previous observations indicate that if the infrared (IR) emission is driven by star formation, then the inferred lensing-corrected star formation rate (SFR) (˜4500 M yr-1) and SFR surface density ΣSFR (˜2000 M yr-1 kpc-2) are both exceptionally high. It remained unclear from the previous data, however, whether a central active galactic nucleus (AGN) contributes appreciably to the IR luminosity. The Chandra upper limit shows that SPT0346-52 is consistent with being star formation dominated in the X-ray, and any AGN contribution to the IR emission is negligible. The ATCA radio continuum upper limits are also consistent with the FIR-to-radio correlation for star-forming galaxies with no indication of an additional AGN contribution. The observed prodigious intrinsic IR luminosity of (3.6 ± 0.3) × 1013 L originates almost solely from vigorous star formation activity. With an intrinsic source size of 0.61 ± 0.03 kpc, SPT0346-52 is confirmed to have one of the highest ΣSFR of any known galaxy. This high ΣSFR, which approaches the Eddington limit for a radiation pressure supported starburst, may be explained by a combination of very high star formation efficiency and gas fraction.
Stellar Masses and Star Formation Rates of Lensed, Dusty, Star-forming Galaxies from the SPT SurveyMa, JingzheGonzalez, Anthony H.Spilker, J. S.Strandet, M.Ashby, Matthew L. N.Aravena, M.Béthermin, M.Bothwell, M. Breuck, C.Brodwin, M.Chapman, S. C.Fassnacht, C. D.Greve, T. R.Gullberg, B.Hezaveh, Y.Malkan, M.Marrone, D. P.Saliwanchik, B. R.Vieira, J. D.Weiß, A.Welikala, N.DOI: info:10.1088/0004-637X/812/1/88v. 81288
Ma, Jingzhe, Gonzalez, Anthony H., Spilker, J. S., Strandet, M., Ashby, Matthew L. N., Aravena, M., Béthermin, M., Bothwell, M. S., de Breuck, C., Brodwin, M., Chapman, S. C., Fassnacht, C. D., Greve, T. R., Gullberg, B., Hezaveh, Y., Malkan, M., Marrone, D. P., Saliwanchik, B. R., Vieira, J. D., Weiß, A., and Welikala, N. 2015. "Stellar Masses and Star Formation Rates of Lensed, Dusty, Star-forming Galaxies from the SPT Survey." The Astrophysical Journal 812:88.
ID: 140579
Type: article
Authors: Ma, Jingzhe; Gonzalez, Anthony H.; Spilker, J. S.; Strandet, M.; Ashby, Matthew L. N.; Aravena, M.; Béthermin, M.; Bothwell, M. S.; de Breuck, C.; Brodwin, M.; Chapman, S. C.; Fassnacht, C. D.; Greve, T. R.; Gullberg, B.; Hezaveh, Y.; Malkan, M.; Marrone, D. P.; Saliwanchik, B. R.; Vieira, J. D.; Weiß, A.; Welikala, N.
Abstract: To understand cosmic mass assembly in the universe at early epochs, we primarily rely on measurements of the stellar masses and star formation rates (SFRs) of distant galaxies. In this paper, we present stellar masses and SFRs of six high-redshift (2.8 ≤ z ≤ 5.7) dusty, star-forming galaxies (DSFGs) that are strongly gravitationally lensed by foreground galaxies. These sources were first discovered by the South Pole Telescope (SPT) at millimeter wavelengths and all have spectroscopic redshifts and robust lens models derived from Atacama Large Millimeter/submillimeter Array observations. We have conducted follow-up observations to obtain multi-wavelength imaging data using the Hubble Space Telescope (HST), Spitzer, Herschel, and the Atacama Pathfinder EXperiment. We use the high-resolution HST/Wide Field Camera 3 images to disentangle the background source from the foreground lens in Spitzer/IRAC data. The detections and upper limits provide important constraints on the spectral energy distributions (SEDs) for these DSFGs, yielding stellar masses, IR luminosities, and SFRs. The SED fits of six SPT sources show that the intrinsic stellar masses span a range more than one order of magnitude with a median value ˜5 ×1010 M. The intrinsic IR luminosities range from 4 × 1012 L to 4 × 1013 L. They all have prodigious intrinsic SFRs of 510-4800 M yr-1. Compared to the star-forming main sequence (MS), these six DSFGs have specific SFRs that all lie above the MS, including two galaxies that are a factor of 10 higher than the MS. Our results suggest that we are witnessing ongoing strong starburst events that may be driven by major mergers.