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{{short description|Astrophysicist}}
{{Use dmy dates|date=January 2023}}
{{Use Indian English|date=January 2023}}
{{Infobox person
| name = Sangeeta Malhotra
| image =
| image_size =
| caption = Sangeeta Malhotra
| birth_date =
| birth_place =
| occupation = [[Astrophysicist]]
| education = [[Delhi University]] (BA, Physics, 1988)<br/>[[Indian Institute of Technology, Kanpur]] (M.A., Physics, 1990)<br/>[[Princeton University]](Ph.D., 1995)
}}

'''Sangeeta Malhotra''' is an astrophysicist who studies galaxies, their contents, and their effects on the universe around them. The objects she studies range from our own Milky Way galaxy to some of the earliest and most distant known galaxies in the epoch of cosmic dawn.

Malhotra works at the [[NASA]] [[Goddard Space Flight Center]], where she is part of the [[Nancy Grace Roman Space Telescope]] project.<ref name="nasabio">{{Cite web|title=Bio - Sangeeta Malhotra|url=https://science.gsfc.nasa.gov/sed/bio/sangeeta.malhotra|website=science.gsfc.nasa.gov|language=en|access-date=2020-05-09}}</ref> She was previously a tenured full professor at [[Arizona State University]].

==Education==
Malhotra received her bachelor's degree in physics from [[Delhi University]] in 1988, and her master's degree in physics from the [[Indian Institute of Technology Kanpur|Indian Institute of Technology -]] Kanpur in 1990. In 1995, she became the first woman of color to receive a PhD in Astrophysics from [[Princeton University]].<ref name="nasabio" /> Her Ph.D. supervisor at Princeton was Professor [[Gillian R. Knapp|Gillian Knapp]]. Malhotra's Ph.D. thesis examined the distribution of atomic and molecular gas in the Milky Way galaxy. Results from her thesis work are reproduced in the textbook "Galactic Structure", by Binney and Merrifield.<ref>{{Cite book|last=Binney, James, 1950-|title=Galactic astronomy|date=1998|publisher=Princeton University Press|others=Merrifield, Michael, 1964-|isbn=0-691-00402-1|location=Princeton, NJ|oclc=39108765}}</ref>

==Career==
After completing her Ph.D., Malhotra first held a postdoctoral fellowship at the [[California Institute of Technology]].<ref name="nasabio" /> She next won a NASA [https://www.stsci.edu/stsci-research/fellowships/nasa-hubble-fellowship-program/2017-and-prior-fellows Hubble Fellowship], which she held at the [[National Optical Astronomy Observatory]] in Tucson and subsequently at the [[Johns Hopkins University]] in Baltimore, Maryland. She then joined the science staff at the [[Space Telescope Science Institute]] in Baltimore, where she worked from 2001 to 2005. She moved to a faculty position at [[Arizona State University]] in Tempe, Arizona in 2006, where she helped build up the new [https://sese.asu.edu School of Earth and Space Exploration].<ref name="nasabio" /> She moved to NASA's [[Goddard Space Flight Center]] in early 2017 to take up a position working on development of the [[Nancy Grace Roman Space Telescope]].

==Research==

=== Infrared Properties of Galaxies ===
Malhotra and collaborators used [[Infrared Space Observatory]] data to study the far-infrared line emission from galaxies. In particular, she demonstrated that the 158 micron emission line of ionized carbon becomes a relatively less prominent spectral feature in galaxies with higher infrared luminosity and/or warmer interstellar dust.<ref>{{Cite journal|last1=Malhotra|first1=S.|last2=Helou|first2=G.|last3=Stacey|first3=G.|last4=Hollenbach|first4=D.|last5=Lord|first5=S.|last6=Beichman|first6=C. A.|last7=Dinerstein|first7=H.|last8=Hunter|first8=D. A.|last9=Lo|first9=K. Y.|last10=Lu|first10=N. Y.|last11=Rubin|first11=R. H.|date=1997-12-10|title=''Infrared Space Observatory'' Measurements of <nowiki>[C ii]</nowiki> Line Variations in Galaxies|journal=The Astrophysical Journal|volume=491|issue=1|pages=L27–L30|doi=10.1086/311044|doi-access=free}}</ref><ref>{{Cite journal|last1=Malhotra|first1=S.|last2=Kaufman|first2=M. J.|last3=Hollenbach|first3=D.|last4=Helou|first4=G.|last5=Rubin|first5=R. H.|last6=Brauher|first6=J.|last7=Dale|first7=D.|last8=Lu|first8=N. Y.|last9=Lord|first9=S.|last10=Stacey|first10=G.|last11=Contursi|first11=A.|date=2001-11-10|title=Far-Infrared Spectroscopy of Normal Galaxies: Physical Conditions in the Interstellar Medium|journal=The Astrophysical Journal|language=en|volume=561|issue=2|pages=766–786|doi=10.1086/323046|arxiv=astro-ph/0106485|bibcode=2001ApJ...561..766M |issn=0004-637X|doi-access=free}}</ref>

=== Lyman Alpha Galaxies and Cosmological Reionization ===
Malhotra initiated the Large Area Lyman Alpha survey<ref>{{Cite journal|last1=Rhoads|first1=James E.|last2=Malhotra|first2=Sangeeta|last3=Dey|first3=Arjun|last4=Stern|first4=Daniel|last5=Spinrad|first5=Hyron|last6=Jannuzi|first6=Buell T.|date=2000-12-20|title=First Results from the Large-Area Lyman Alpha Survey|url=https://iopscience.iop.org/article/10.1086/317874|journal=The Astrophysical Journal|volume=545|issue=2|pages=L85–L88|doi=10.1086/317874 | arxiv=astro-ph/0003465|bibcode=2000ApJ...545L..85R |s2cid=16732902 }}</ref> in the late 1990s. This was one of the first research projects to successfully identify galaxies in the early universe using their [[Lyman-alpha line|Lyman alpha]] emission lines, a method that had been first proposed in 1967 by Bruce Partridge and [[Jim Peebles]].<ref>{{Cite journal|last1=Partridge|first1=R. B.|last2=Peebles|first2=P. J. E.|date=1967|title=Are Young Galaxies Visible?|journal=The Astrophysical Journal|language=en|volume=147|pages=868|doi=10.1086/149079|bibcode=1967ApJ...147..868P |issn=0004-637X|doi-access=free}}</ref> She has gone on to study [[Lyman-alpha emitter|galaxies with strong Lyman alpha lines]] in detail. In particular, she demonstrated that they tend to be young, with extreme star formation properties<ref>{{Cite journal|last1=Malhotra|first1=Sangeeta|last2=Rhoads|first2=James E.|date=2002-02-01|title=Large Equivalent Width L[CLC]y[/CLC]α line Emission at <nowiki>z=4.5</nowiki>: Young Galaxies in a Young Universe?|journal=The Astrophysical Journal|volume=565|issue=2|pages=L71–L74|doi=10.1086/338980 |arxiv=astro-ph/0111126|doi-access=free}}</ref> and (for galaxies) small sizes.<ref>{{Cite journal|last1=Malhotra|first1=Sangeeta|last2=Rhoads|first2=James E.|last3=Finkelstein|first3=Steven L.|last4=Hathi|first4=Nimish|last5=Nilsson|first5=Kim|last6=McLinden|first6=Emily|last7=Pirzkal|first7=Norbert|date=2012-05-10|title=SIZING UP Lyα AND LYMAN BREAK GALAXIES|url=https://iopscience.iop.org/article/10.1088/2041-8205/750/2/L36|journal=The Astrophysical Journal|volume=750|issue=2|pages=L36|doi=10.1088/2041-8205/750/2/L36|issn=2041-8205|arxiv=1106.2816|bibcode=2012ApJ...750L..36M |s2cid=119194628 }}</ref>

She also pioneered the technique of using Lyman alpha galaxies to study cosmological reionization, leading a 2004 paper that demonstrated that the gas between galaxies was already mostly ionized at redshift 6.5, when the universe was less than a billion years old.<ref>{{Cite journal|last1=Malhotra|first1=Sangeeta|last2=Rhoads|first2=James E.|date=2004-12-10|title=Luminosity Functions of Lyα Emitters at Redshifts z = 6.5 and z = 5.7: Evidence against Reionization at z ≤ 6.5|url=https://iopscience.iop.org/article/10.1086/427182|journal=The Astrophysical Journal|language=en|volume=617|issue=1|pages=L5–L8|doi=10.1086/427182 | arxiv=astro-ph/0407408|bibcode=2004ApJ...617L...5M |s2cid=118915884 |issn=0004-637X}}</ref> Recently, she, her former Ph.D. student V. S. Tilvi, and other collaborators identified the most distant galaxy group so far known (EGS77), and found evidence that these galaxies are ionizing their surroundings.<ref>{{Cite web|title=Astronomers Spot Distant Galaxy Group Driving Ancient Cosmic Makeover|url=http://www.nasa.gov/feature/goddard/2020/astronomers-spot-distant-galaxy-group-driving-ancient-cosmic-makeover|last=Jenner|first=Lynn|date=2019-12-31|website=NASA|access-date=2020-05-09}}</ref><ref>{{Cite journal|last1=Tilvi|first1=V.|last2=Malhotra|first2=S.|last3=Rhoads|first3=J. E.|last4=Coughlin|first4=A.|last5=Zheng|first5=Z.|last6=Finkelstein|first6=S. L.|last7=Veilleux|first7=S.|last8=Mobasher|first8=B.|last9=Wang|first9=J.|last10=Probst|first10=R.|last11=Swaters|first11=R.|date=2020-02-27|title=Onset of Cosmic Reionization: Evidence of an Ionized Bubble Merely 680 Myr after the Big Bang|journal=The Astrophysical Journal|volume=891|issue=1|pages=L10|doi=10.3847/2041-8213/ab75ec|issn=2041-8213|arxiv=2001.00873|bibcode=2020ApJ...891L..10T |s2cid=209832401 |doi-access=free }}</ref> She is the US [[principal investigator]] of the ongoing multinational [http://www.lagersurvey.org LAGER project] (Lyman Alpha Galaxies in the Epoch of Reionization), which is identifying hundreds of Lyman alpha galaxies in the epoch of cosmic dawn.

=== Slitless Spectroscopy from Space ===
Malhotra has led three [[Hubble Space Telescope]] treasury programs<ref>{{Cite web|title=HST Treasury Proposals|url=http://archive.stsci.edu/hst/treasury.html|website=archive.stsci.edu|access-date=2020-05-08}}</ref> ([https://archive.stsci.edu/prepds/grapes/ GRAPES], [https://archive.stsci.edu/prepds/pears/ PEARS], and FIGS<ref>{{Cite journal|last1=Pirzkal|first1=Norbert|last2=Malhotra|first2=Sangeeta|last3=Ryan|first3=Russell E.|last4=Rothberg|first4=Barry|last5=Grogin|first5=Norman|last6=Finkelstein|first6=Steven L.|last7=Koekemoer|first7=Anton M.|last8=Rhoads|first8=James|last9=Larson|first9=Rebecca L.|last10=Christensen|first10=Lise|last11=Cimatti|first11=Andrea|date=2017-09-01|title=FIGS—Faint Infrared Grism Survey: Description and Data Reduction|journal=The Astrophysical Journal|language=en|volume=846|issue=1|pages=84|doi=10.3847/1538-4357/aa81cc|arxiv=1706.02669 |bibcode=2017ApJ...846...84P |issn=1538-4357|hdl=10150/625750|s2cid=38863528 |hdl-access=free |doi-access=free }}</ref>) that have collectively advanced the application of [[Slitless spectroscopy|slitless spectroscopic]] observations from space. While initially designed to identify galaxies in the distant universe,<ref>{{Cite journal|last1=Malhotra|first1=S.|last2=Rhoads|first2=J. E.|last3=Pirzkal|first3=N.|last4=Haiman|first4=Z.|last5=Xu|first5=C.|last6=Daddi|first6=E.|last7=Yan|first7=H.|last8=Bergeron|first8=L. E.|last9=Wang|first9=J.|last10=Ferguson|first10=H. C.|last11=Gronwall|first11=C.|date=2005-06-20|title=An Overdensity of Galaxies at z = 5.9 + 0.2 in the Hubble Ultra Deep Field Confirmed Using the ACS Grism|url=https://iopscience.iop.org/article/10.1086/430047|journal=The Astrophysical Journal|language=en|volume=626|issue=2|pages=666–679|doi=10.1086/430047|issn=0004-637X|arxiv=astro-ph/0501478|bibcode=2005ApJ...626..666M |s2cid=55026837 }}</ref><ref>{{Cite journal|last1=Rhoads|first1=James E.|last2=Malhotra|first2=Sangeeta|last3=Stern|first3=Daniel|last4=Dickinson|first4=Mark|last5=Pirzkal|first5=Norbert|last6=Spinrad|first6=Hyron|last7=Reddy|first7=Naveen|last8=Hathi|first8=Nimish|last9=Grogin|first9=Norman|last10=Koekemoer|first10=Anton|last11=Peth|first11=Michael A.|title=A Lyman Break Galaxy in the Epoch of Reionization Fromhubble Space Telescopegrism Spectroscopy|date=2013-07-22|journal=The Astrophysical Journal|volume=773|issue=1|pages=32|doi=10.1088/0004-637X/773/1/32|arxiv=1302.7005|bibcode=2013ApJ...773...32R |issn=0004-637X|doi-access=free}}</ref><ref>{{Cite journal|last1=Tilvi|first1=V.|last2=Pirzkal|first2=N.|last3=Malhotra|first3=S.|last4=Finkelstein|first4=S. L.|last5=Rhoads|first5=J. E.|last6=Windhorst|first6=R.|last7=Grogin|first7=N. A.|last8=Koekemoer|first8=A.|last9=Zakamska|first9=N. L.|last10=Ryan|first10=R.|last11=Christensen|first11=L.|date=2016-08-05|title=FIRST RESULTS FROM THE FAINT INFRARED GRISM SURVEY (FIGS): FIRST SIMULTANEOUS DETECTION OF Ly α EMISSION AND LYMAN BREAK FROM A GALAXY AT z = 7.51|journal=The Astrophysical Journal|volume=827|issue=1|pages=L14|doi=10.3847/2041-8205/827/1/L14|issn=2041-8213|arxiv=1605.06519|bibcode=2016ApJ...827L..14T |s2cid=119295160 |doi-access=free }}</ref> these projects have also proven invaluable for identifying galaxies at intermediate distances,<ref>{{Cite journal|last1=Pirzkal|first1=N.|last2=Xu|first2=C.|last3=Ferreras|first3=I.|last4=Malhotra|first4=S.|last5=Mobasher|first5=B.|last6=Rhoads|first6=J. E.|last7=Pasquali|first7=A.|last8=Panagia|first8=N.|last9=Koekemoer|first9=A. M.|last10=Ferguson|first10=H. C.|last11=Gronwall|first11=C.|date=2006-01-10|title=Morphology and Evolution of Emission-Line Galaxies in the Hubble Ultra Deep Field|url=https://iopscience.iop.org/article/10.1086/498129|journal=The Astrophysical Journal|language=en|volume=636|issue=2|pages=582–591|doi=10.1086/498129|issn=0004-637X|arxiv=astro-ph/0509551|bibcode=2006ApJ...636..582P |s2cid=6560960 }}</ref> studying the chemical compositions of those galaxies,<ref>{{Cite journal|last1=Xia|first1=Lifang|last2=Malhotra|first2=Sangeeta|last3=Rhoads|first3=James|last4=Pirzkal|first4=Nor|last5=Straughn|first5=Amber|last6=Finkelstein|first6=Steven|last7=Cohen|first7=Seth|last8=Kuntschner|first8=Harald|last9=Kümmel|first9=Martin|last10=Walsh|first10=Jeremy|last11=Windhorst|first11=Rogier A.|date=2012-07-01|title=METALLICITIES OF EMISSION-LINE GALAXIES FROM HST ACS PEARS AND HST WFC3 ERS GRISM SPECTROSCOPY AT 0.6 < z < 2.4|url=https://iopscience.iop.org/article/10.1088/0004-6256/144/1/28|journal=The Astronomical Journal|volume=144|issue=1|pages=28|doi=10.1088/0004-6256/144/1/28|issn=0004-6256|arxiv=1205.3172|bibcode=2012AJ....144...28X |s2cid=118501972 }}</ref><ref>{{Cite journal|last1=Pharo|first1=John|last2=Malhotra|first2=Sangeeta|last3=Rhoads|first3=James|last4=Christensen|first4=Lise|last5=Finkelstein|first5=Steven L.|last6=Grogin|first6=Norman|last7=Harish|first7=Santosh|last8=Jiang|first8=Tianxing|last9=Kim|first9=Keunho|last10=Koekemoer|first10=Anton|last11=Pirzkal|first11=Norbert|date=2019-03-29|title=Emission-line Metallicities from the Faint Infrared Grism Survey and VLT/MUSE|journal=The Astrophysical Journal|volume=874|issue=2|pages=125|doi=10.3847/1538-4357/ab08ec|arxiv=1810.12342 |bibcode=2019ApJ...874..125P |hdl=11585/732007 |s2cid=56066945 |issn=1538-4357 |doi-access=free }}</ref> and even studying stars in our own Galaxy.<ref>{{Cite journal|last1=Pirzkal|first1=N.|last2=Sahu|first2=K. C.|last3=Burgasser|first3=A.|last4=Moustakas|first4=L. A.|last5=Xu|first5=C.|last6=Malhotra|first6=S.|last7=Rhoads|first7=J. E.|last8=Koekemoer|first8=A. M.|last9=Nelan|first9=E. P.|last10=Windhorst|first10=R. A.|last11=Panagia|first11=N.|date=2005-03-20|title=Stars in the Hubble Ultra Deep Field|url=https://iopscience.iop.org/article/10.1086/427896|journal=The Astrophysical Journal|language=en|volume=622|issue=1|pages=319–332|doi=10.1086/427896 |arxiv=astro-ph/0412097|bibcode=2005ApJ...622..319P |s2cid=7588745 |issn=0004-637X}}</ref> Further developments of these techniques form a core part of the planned observing programs for ESA's [[Euclid (spacecraft)|''Euclid'' mission]] and NASA's [[Nancy Grace Roman Space Telescope|''Roman'' mission]], and Malhotra is helping develop plans for the ''Roman'' application.

=== Pea galaxies ===
Malhotra has directed multiple PhD students in studying [[Pea galaxy|Green Pea galaxies]]. She and her collaborators have demonstrated that these comparatively local objects bear striking similarities to Lyman alpha galaxies in the early universe,<ref>{{Cite journal|last1=Yang|first1=Huan|last2=Malhotra|first2=Sangeeta|last3=Gronke|first3=Max|last4=Rhoads|first4=James E.|last5=Dijkstra|first5=Mark|last6=Jaskot|first6=Anne|last7=Zheng|first7=Zhenya|last8=Wang|first8=Junxian|date=2016-03-30|title=GREEN PEA GALAXIES REVEAL SECRETS OF Ly α ESCAPE|journal=The Astrophysical Journal|volume=820|issue=2|pages=130|doi=10.3847/0004-637X/820/2/130|issn=1538-4357|arxiv=1506.02885|bibcode=2016ApJ...820..130Y |s2cid=118400206 |doi-access=free }}</ref><ref>{{Cite journal|last1=Yang|first1=Huan|last2=Malhotra|first2=Sangeeta|last3=Gronke|first3=Max|last4=Rhoads|first4=James E.|last5=Leitherer|first5=Claus|last6=Wofford|first6=Aida|last7=Jiang|first7=Tianxing|last8=Dijkstra|first8=Mark|last9=Tilvi|first9=V.|last10=Wang|first10=Junxian|date=2017-08-03|title=Ly α Profile, Dust, and Prediction of Ly α Escape Fraction in Green Pea Galaxies|journal=The Astrophysical Journal|volume=844|issue=2|pages=171|doi=10.3847/1538-4357/aa7d4d|arxiv=1701.01857 |bibcode=2017ApJ...844..171Y |issn=1538-4357|hdl=10852/60241|s2cid=56422449 |hdl-access=free |doi-access=free }}</ref> which is valuable because the pea galaxies are easier to study in detail than their more distant counterparts.{{fact|date=January 2023}}

== Students ==

Malhotra has advised over a half dozen Ph.D. thesis students, including Steven Finkelstein, Nimish Hathi, Vithal Tilvi, Lifang Xia, Huan Yang, Tianxing Jiang, and John Pharo.<ref>{{Cite web|title=Sangeeta Malhotra - The Mathematics Genealogy Project|url=https://genealogy.math.ndsu.nodak.edu/id.php?id=138515&fChrono=1|website=genealogy.math.ndsu.nodak.edu|access-date=2020-05-09}}</ref>

== Awards and honors ==
Malhotra was awarded a NASA Hubble Fellowship in 1998.<ref>{{Cite web|title=2017 and Prior Fellows|url=http://www.stsci.edu/home/stsci-research/fellowships/nasa-hubble-fellowship-program/2017-and-prior-fellows|website=STScI.edu|language=en|access-date=2020-05-08}}</ref><br />She is a Legacy Fellow of the [[American Astronomical Society]].<ref>{{Cite web|title=AAS Fellows Program {{!}} American Astronomical Society|url=https://aas.org/grants-and-prizes/aas-fellows|website=aas.org|access-date=2020-05-08}}</ref>

==References==
{{Reflist}}

{{authority control}}

{{DEFAULTSORT:Malhotra, Sangeeta}}
[[Category:Indian astrophysicists]]
[[Category:Living people]]
[[Category:NASA astrophysicists]]
[[Category:20th-century Indian astronomers]]
[[Category:20th-century Indian women scientists]]
[[Category:21st-century Indian astronomers]]
[[Category:21st-century Indian women scientists]]
[[Category:Fellows of the American Astronomical Society]]
[[Category:Delhi University alumni]]
[[Category:IIT Kanpur alumni]]
[[Category:Princeton University alumni]]
[[Category:Year of birth missing (living people)]]

Sangeeta Malhotra - Revision history

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